IR-brightness temperature and IMERG over South America

Infrared brightness temperature (top panel) and IMERG precipitation (bottom panel) at 10 km resolution and hourly intervals. IMERG is a high resolution dataset that relies extensively on satellite microwave imagery.

Provided by Zhe Feng.

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May 17-30, 2021: Radar and satellite imagery over eastern US

Infrared brightness temperature (top panel) and NEXRAD radar reflectivity mosaics (bottom panel) over the eastern US (110W-70W), at hourly intervals. The radar reflectivity has 4 km resolution. Because the file is large, it is best viewed manually controlling the speed of advance.

Provided by Zhe Feng.

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May 17, 2021: Storms over Texas: IR and visible satellite imagery

A closer look at the deep convection over Texas and Louisiana in the previous video, as revealed by imagery. The last clip shows a mix of visible and IR imagery, referred to as "sandwich imagery”. Lightning locations are also shown in some of the clips.

Provided by NOAA/NESDIS, based on data from imagers carried aboard the GOES 16 satellite.

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May 17, 2021: Lightning Locations

A more leisurely look at lightning locations during the 24 h interval starting at 1100 LT May 17. Each flash fades from black to yellow to white over a 10 minute interval.

Based on data from the Geostationary Lightning Mapper (GLM) on Geostationary Operational Environmental Satellite (GOES-16). Provided by Katrina Virts.

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November 2023: Lightning flashes over Australia

A more comprehensive view of deep convection, as revealed by lightning locations. Grid boxes that have experienced lightning since the beginning of the month are shaded in blue.

Provided by Andrew Miskelly / Weatherzone.

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Temperature at 2 m

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SLP

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Surface wind (at 10 m)

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Precipitable water

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Precipitation

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Lightning

Based on data from the Worldwide Lightning Location Network (WWLLN). Provided by Katrina Virts.

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Ice, snow cover, and vegetation

At 2-week intervals. Vegetation based in NDVI.

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Sea surface temperature, 2016-2020

A tour of the world oceans spanning 4+ years featuring the Jet Propulsion Laboratory (JPL) SST Analysis. Portrays the role of the ocean in the atmospheric general circulation. Shows the warm pool, the western boundary currents, SST fronts with their slowly evolving eddies and meanders, the equatorial cold tongues, tropical instability waves, coastal upwelling, and the large-scale, high frequency response to bursts of atmospheric forcing.

Provided by NASA/SVS.

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Skin temperature over land, 2000-2013

These maps show monthly daytime land-surface temperatures based on MODIS imagery. The measurements shown here represent the temperature of the "skin" (or top 1 millimeter) of the land surface during the daytime—including bare land, snow or ice cover, and surface air temperature may be quite different. Yellow indicates the warmest temperatures (45°C) and light blue the coldest (< -25°C).

Provided by NASA/Earth Observatory.

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Focus on Australia

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Focus on the North Pacific

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Gross primary productivity (2000-2009)

The uptake of carbon by land plants by photosynthesis during the growing season is the dominant atmospheric CO₂ sink. It is monitored using multi-channel radiances sensed by the MODIS instrument carried aboard NASA’s Aqua satellite. This video shows the evolving distribution of gross primary productivity over land during the ten year period 2000-2009: the darker the color, the higher the productivity. The variability is dominated by the seasonally varying climatological mean, but year-to-year variability is also discernible. Features associated with topography and land use are evident.

Provided by NASA/GMAO through NASA's GeoEye Scientific Visualization Studio (SVS).

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Snow and ice cover, 2019-2021

The evolving distribution of snow and ice cover over the Northern and Southern Hemispheres, 2019-2021. The time step is about 5 days.

Provided by NASA/SVS.

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Sea ice motion, 1979-2022

Tracks of drifting buoys, indicated by the red circles with the blue tails, superimposed upon fractional areal sea ice coverage, indicated by the shading (white ice covered, dark blue ice free).

From the International Arctic Buoy Program. Provided by Ignatius Rigor.

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The fruit fly: surface temperature

The spatial distribution of surface temperature in a very simple general circulation model without a hydrologic cycle. Red denotes warm and blue cold. The maps are on a rectangular grid, with the top and bottom of the frame at poles. In the first few frames of the video, the meridional temperature gradient strengthens in response to the differential heating. When it reaches a critical value, baroclinic instability breaks out.

Provided by Isaac Held.

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The fruit fly: zonal wind at the jet stream level

The lighter the shading, the stronger the westerlies. The first few frames are black because the westerlies are just beginning to develop. Zonally symmetric westerly jet streams develop in midlatitudes and quickly become distorted and concentrated in narrow, zonally varying jet streams by baroclinic waves, whose axes systematically tilt eastward from west to east.

Provided by Isaac Held.

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High resolution model: Column water vapor

A "spin up" simulation with a high resolution atmospheric model run in an aquaplanet configuration, showing the field of column-integrated water vapor W (brighter colors indicate higher values).

The model used in this experiment is the Energy Exascale Earth System Model (E3SM) project supported by the Office of Science/US Department of Energy. The top panels of Fig. 4.4 in the text are snapshots from this animation. The first generation of amplifying baroclinic waves distorts the meridional gradient of W. The perturbations are linear at first, but they become nonlinear as soon as the waves grow to finite amplitude.

Provided by Lai-Yung Leung and Mark Taylor.

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Spin down experiment

Friction acting the boundary layer at the bottom of the cup reduces the centripital acceleration and gives rise to radial component of the flow that concentrates the tea leaves a the center of the cup. From Wikipedia.

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Pressure wave, Japan, first pass

Shows surface pressure time series at a dense network of stations, documenting the passage of a northwestward propagating pressure rise followed by a pressure drop, with a peak-to-peak amplitude of ~1 hPa. Weaker waves traveling at the same phase speed are also discernible. The warm colors represent positive pressure perturbations and the blue negative perturbations.

Provided by Weathernews. Additional Tonga videos can be viewed here.

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Pressure wave, Japan, third pass

Second train of waves that arrived about 35 h later than those shown in the previous video after having passed through the antipodal point and returned to the point of origin and reemerged.

Provided by Weathernews. Additional Tonga videos can be viewed here.

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7 μm band, time filtered, gray scale

Water vapor imagery in the 7 um band, high pass filtered in time to reveal the most rapidly evolving features and rendered in a gray scale. The frames are at 10 minute intervals.

Provided by Mathew Barlow.

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7 μm band, time filtered, color

Water vapor imagery in the 7 um band, high pass filtered in time to reveal the most rapidly evolving features and rendered in colored shading. The orange and blue shading indicate positive and negative pressure perturbations, respectively.

Provided by Mathew Barlow.

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7 μm band, time filtered, gray scale 60 h, multiple passes

As in a previous animation showing the Lamb wave excited by the Tonga explosion, but this 60-hour-long version is long enough to show it reaching its antipodal point, propagating back to its point of origin and propagating out again.

Provided by Mathew Barlow.

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Simulated Lamb Wave

Response of a shallow water wave equation model with an equivalent depth of 10 km forced with a delta function "explosion” in the space and time domains at the site of the explosion. The colors represent the perturbations in the pressure and temperature fields, which assume the same form. In this sequence of images, the orange and blue shading indicate positive and negative perturbations, respectively. Lamb waves have a dual identity as sound waves and gravity waves. They propagate at the speed of sound.

Provided by Nedjeljka Zagar.

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Low clouds cleared by downwelling gravity wave

As in the still image shown in Fig. 2.20 of the text, stratus cloud decks are cleared by subsidence warming associated with a downwelling gravity wave. From Gulf of Carpentaria north of Australia.

First clip: August 15, 2023.

Provided by Andrew Miskelly / Weatherzone.

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Trapped waves in the wake of MacQuarie Island, March 15, 2022

The stationary orographic imprint of MacQuarie Island at 55°S in the Southern Ocean, directly south of the Tasman Sea, upon a deck low clouds passing over it in a WSW air stream. The length and NNW-SSE orientation of the waves axes matches the shape of the island. The low clouds are mainly closed cell convection.

Provided by Andrew Miskelly / Weatherzone.

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Trapped waves in various settings

Trapped mountain lee waves are a common occurrence. This video shows examples of waves in three different settings: the first clip shows waves over Lake Superior oriented perpendicular to the upstream shoreline. The second shows waves over the mountain ranges of upper New York State and New England, and the third shows moist marine air flowing over Tasmania, with the shallow convection being transformed into a quasistationary trapped mountain lee wave pattern. The intermittent signature of higher, vertically propagating waves is discernible downstream.

Provided by CIRA.

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Vertically propagating waves, US Great Plains, January 19, 2024

Vertically propagating gravity waves to the east of the Rockies. The sharp upstream edge of the extensive deck of high clouds of high clouds, anchored along the front range of the Rockies, coincides with the band of ascent downstream of the idealized mountain range in Fig. 3.2 of the text. The lifting in the waves is sufficient to cool the air, until it becomes saturated and remains so as the air passes over the Plains.

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Lenticular formation over Wellington, NZ, 29 May, 2019

Quasi-stationary orographically forced, vertically-propagating wave clouds can be distinguished from the rapidly moving low clouds. The camera is pointing toward the northeast. The wave clouds are above and downstream of the Remutaka Range of the North Island, and the low-level flow is from the north-northwest and being channelled through Cook Strait.

Provided by Meteorological Service of NZ Ltd.

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Gulf of Tehuantepec, February 6, 2024

The Gulf of Tehuantepec lies downstream of a saddle point in the mountain range that forms the backbone of Central America, with altitudes substantially lower than to the east or west. When cold airmasses propagate southward along the eastern side of the Rockies into Texas and northern Mexico, their attendant pressure surges penetrate deep into Central America, giving rise to a strong pressure difference across the range. An overview of the channing of the wind by the orography, as revealed by the motion of the low clouds.

Provided by CIRA.

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Gulf of Tehuantepec, April 29, 2023

Strong winds flowing through the gap raise a cloud of dust, which remains airborne as the gap flow descends and spreads out over the Gulf. The arc of enhanced low clouds that precedes the arrival of the dust looks like it might be gravity wave signature.

Provided by CIRA.

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Tasmania, May 11, 2023

A stratus cloud deck is deflected around the island of Tasmania. The blocking is obviously related to the topography of the island. A cloud-free wake of the island extends downstream.

Provided by Andrew Miskelly / Weatherzone.

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Cook Strait, New Zealand, June 5, 2023

The Cook Strait, which separates the North and South Islands of New Zealand, is a frequent site of gap winds, which can blow in either direction depending on the synoptic situation. Here they are from east to west, down the pressure gradient, rendered visible by the presence of a low cloud deck. Visible imagery.

Provided by Andrew Miskelly / Weatherzone.

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Davis Strait, April 16, 2021

Much of the time during winter, SLP is higher over the Arctic than over the Labrador Sea, near the southern tip of Greenland, and the winds in the boundary layer blow from the north, down the pressure gradient between the high terrain of Greenland and Baffin Island. Shallow convection, in response to the flow of cold, Arctic air over open water, gives rise to stratocumulus cloud decks. Visible imagery.

Provided by CIRA.

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Arizona

The haboobs in this video were generated by the outflow from downdrafts in thunderstorms over Arizona. Those shown in Part I are shallow and do not bear an obvious relation to the convection that caused them, whereas those shown in Part II move in tandem with features embedded in the base of the updraft, indicative of a deeper structure. Provided by Mike Olbinski. For more about him and his videos, see Animation 16-5.

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Mexico, April 25, 2022

Haboobs behind gust fronts from convective cells propagate westward until they are blocked by the mountain range. The city lights in the last frames are the video are the lights of Monterrey. GeoColor imagery.

Provided by CIRA.

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Argentina, December 18, 2020

The gust front of an advancing cold surge triggered a massive dust storm.

Provided by CIRA.

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A global perspective: March 2003 to January 2022

Based on the the Global Fire Emissions Database version 4, showing carbon emissions with 0.25 degree spatial resolution and 7 day time resolution. Includes both managed agricultural fires and wildfires. Expressed in units of carbon emission.

An example of the former is the fires over northern India in April-May, which corresponds to the burning of the stubble from the winter wheat crop, and over the Punjab during October-November, which corresponds to the burning of the stubble from the summer rice crop. Arctic wildfires show up prominently during the boreal summer.

Provided by NASA SVS.

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Wildfire outbreaks, 2023

A sequence of short clips showing wildfire outbreaks in different geographical regions. Some of the fires are accompanied by deep convection forced by the combustion, which lofts the smoke high into the atmosphere.

Apart from the first one, which is included to provide a detailed view of fire-related convection, the clips are arranged in chronological order. The second shows fires in Chile, the next four show forest in western Canada in mid-May, the next two fires in Quebec in June, and the last one a part of the disastrous fire on Maui in the Hawaiian islands on August 9.

Provided by CIRA. By downloading the video and advancing it manually, it is possible to view the clips one-by-one.

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Australian bushfire, September 3-11, 2023

In this week-long sequence, a bushfire intrudes into the surrounding area in a series of wind-driven bursts, as the burn scar, indicated by the black shading, expands into new territory. The fire threatens the town of Tennant Creek to the west.

Provided by Andrew Miskelly / Weatherzone.

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Saharan dust, April 2020

Dates and times are shown in the bottom right corner. The discontinuities from 1200 to 1300 UT each day are an artifact of the data processing.

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Ash cloud from Tonga eruption, January 15-18, 2022

The ash cloud injected into the stratosphere, drifted westward in an easterly wind regime of the QBO at an altitude of about 25 km. Based on Himawari 8 Ash RGB imagery.

Provided by Andrew Miskelly / Weatherzone.

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Smoke from Australian bush fires, November 1-18, 2019

Black carbon smoke rendered in white.

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Smoke from Arctic boreal forest wildfires, June-August 2019

Expressed as aerosol optical depth.

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Canadian wildfire smoke over the northeastern US, June 7, 2023

Over the northern US, to the east of the Rockies, summer 2023 was marked by extended episodes of smoke pollution from fires in the boreal forests over Canada. One of the worst occurred on June 7 over the Northeast, including the New York City area. The shielding of solar radiation by the smoke suppressed the heating of the surface that drives the daytime convection, as evidenced by the absence of cumulus clouds within the smoke plume.

Provided by CIRA.

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Aerosols, August 2018 - January 2020

Atmospheric aerosols are categorized by tint: dust (orange), smoke (red) organic/black carbon (green), and sulfates (white), displayed in terms of their extinction aerosol optical thickness. Water vapor is shown in a duller white.

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CO from Arctic wildfires, June-August 2019

CO from wildfire outbreaks in the boreal forests, Summer 2019 — the same year as the video showing the aerosol transport.

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CO, December 2006

Hourly CO concentration. The concentration scale spans light blue (lowest) to black (highest). Note the sporadic export in well-defined plumes emanating from industrial regions and regions of agricultural burning.

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CH₄, 2017 and 2018

The color scale is designed to emphasize the small contrast between the concentrations in the source regions, which range up to 2100 ppb and the background contribution (~1800 ppb). Because of the longer residence time of CH₄, the plumes from the regions of emissions can be traced farther downstream than their counterparts in the CO distribution.

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CO and CO₂, 2016

CO concentration is rendered on a gray scale, and CO₂ concentration on a color scale at the bottom. CO₂ is visible only where the concentration is above the reference value of 380 ppmv. The higher values are due to the presence of sources, mainly in the Northern Hemisphere. Note the summer drawdown due to the uptake of CO₂ by the boreal forests.

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Rain rate based on IMERG, April-September 2014

The acronym IMERG stands for integrated, multi-channel retrievals for NASA's Global Precipitation Mission (GPM), which provides estimates of rate of precipitation all over the globe at 30 minute intervals on an approximately 1 x 1 km grid, extending back to 1998. This product is based on a synthesis of measurements from satellites operated by the US and Japan. The cool colors indicate frozen precipitation.

Provided by NASA's Scientific Video Studio (SVS).

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Clouds and precipitable water, global, April through July 2006

Clouds, as inferred from infrared satellite imagery, are rendered in white. This video is also pertinent to the last two sections of Chapter 14.1, where the field of column water vapor is discussed in the context of the tropical general circulation.

Produced using the GEOS5 data assimilation system. Provided by the NASA/GMAO.

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Clouds and precipitable water, Marine Continent / Australia, 2022

Column water vapor (black / white shading) and precipitation (colored shading) based on the NOAA Global Forecast System model.

Provided by Andrew Miskelly / Weatherzone.

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Precipitable water, Marine Continent / Australia, 2023

Provided by Andrew Miskelly / Weatherzone.

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Ocean surface salinity, 2011-2021

This video serves as a companion to Fig. 4.12 in the text, providing additional spatial resolution and revealing the seasonality. The time-varying outflow from the Ganges, the Amazon, the Congo, the St. Lawrence and other large river systems is clearly discernible. Patches of relatively fresh water from the Bay of Bengal can be seen flowing westward south of India into the saltier Arabian Sea.

Provided by the NASA/SVS.

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Snow and ice cover, 2019-2021

The evolving distribution of snow and ice cover over the Northern and Southern Hemispheres, 2019-2021. The time step is about 5 days.

Provided by NASA/SVS.

(1:01)

Sea ice motion, 1979-2022

Tracks of drifting buoys, indicated by the red circles with the blue tails, superimposed upon fractional areal sea ice coverage, indicated by the shading (white ice covered, dark blue ice free).

From the International Arctic Buoy Program. Provided by Ignatius Rigor.

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TOA net radiation and cloud fraction

Monthly net top-of-atmosphere net radiation and cloud fraction. The seasonal cycle is dominated by net downward radiation in the summer hemisphere and upward radiation in the winter hemisphere.

Based on the Clouds and the Earth's Radiant Energy System (CERES) sensors on NASA's Aqua and Terra satellites. Provided by the NASA/Earth Observatory. Provided by the NASA/Earth Observatory.

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Shallow convection off the coasts of Australia

The first clip shows an intricate pattern of shallow convection in a spreading cold air mass over the Australian bight. In the second clip, a cold frontal rainband is approaching the coast, with open cell convection covering the expansive zone of cold advection behind it.

The third clip zooms in on the convection in the trough behind the front. The fourth clip shows convective cells over the same region on a different day, which assume a dendritic (branching) form, with subtle regional variations. The fifth clip shows a close-up of dendritic cells that are twisted into a cyclonic vortex.

The sixth shows dendritic cells over the tropical Indian Ocean off the northwest of Australia, which is organized into lines, one of which develops along the hook-shaped rear edge of a plume of wildfire smoke. The final clip shows cloud streets over the Coral Sea.

Provided by Andrew Miskelly / Weatherzone. The clips in this video are very short. The viewer is advised to download the video and advance it manually so that each clip can be viewed backwards and forwards at leisure.

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Cloud streets off the East Asian coasts, January 25, 2023

Frequently observed when cold continental air masses flow over the warmer offshore waters. Visible imagery.

Provided by Andrew Miskelly / Weatherzone.

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Cloud streets off the US eastern seaboard, December 20, 2022

GeoColor imagery. Provided by CIRA.

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Cloud streets over Lake Superior, March 29, 2023

GeoColor imagery. Provided by CIRA.

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Poleward eddy heat transport

Surface temperature over the Northern Hemisphere with emphasis on the North American sector, Dec 1, 2022 to Jan 3 2023. Numerous cyclones developed over the Atlantic and Pacific storm tracks during this month-long period. The warmer airstreams are consistently moving poleward and the colder airstreams equatorward, resulting in a poleward eddy heat transport. Based on satellite imagery assimilated using the GEOS5 model.

Provided by the NASA/Earth Observatory.

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Breakdown of a vortex line due to shear instability, November 23, 2022

Upper tropospheric water vapor imagery. A remarkably thin, elongated, north-south oriented band of dry air, drifting eastward across the Tasman Sea, abruptly breaks down into a line of cyclonic vortices. The motions are not clearly revealed by the satellite imagery until the breakdown is underway, when it becomes apparent that the dry band is marked by strong cyclonic shear. It is conceivable that this feature could be related to a tropopause fold, as discussed in Section 9.1.4 of the text.

Provided by Andrew Miskelly / Weatherzone.

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Shear instability along a dry filament, June 7, 2017

The easterly flow poleward of an extended east-west oriented trough becomes barotropically unstable, and the waves that develop wrap up into cyclonic vortices. The waves are rendered visible in this water vapor band imagery by the presence of a dry filament within the shear zone.

Provided by CIRA.

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February 2-20, 2010: Clouds, global domain, GEOS5 imagery

Shows clouds as assimilated in GEOS5 at a resolution of 5-km per grid cell with 30 minute time resolution for February 2-20, 2010. The video shows numerous extratropical cyclones evolving through their life cycles along the extratropical storm tracks, the trade winds, the ITCZs, tropical convection over land, and the diurnal cycle, illustrating the wide range of space and time scales of encompassed by the atmospheric general circulation.

Provided by NASA/GMAO.

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February 2-20, 2010: Clouds, North America, GEOS5 imagery

The same animation zoomed in to show weather systems passing over North America and the western Atlantic. This sequence includes several LC2 storms. Shallow convection is discernible off the US eastern seaboard following the passage of cold fronts.

Provided by the NASA/Earth Observatory.

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January-August 2014: Tasman Sea - Infrared imagery

The cloud patterns associated with baroclinic waves in this sector are remarkably diverse, owing to the presence of split flow, with higher and lower latitude branches of the jet stream. The complexity is heightened by the New Zealand Alps, which are high enough to distort the flow patterns but not high enough to block them. Orographically forced wave clouds often form downstream of the Alps, as described in Supplemental figures 3.1a.b.

Provided by James Renwick and James McGregor.

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Feb. 2, 2018: Polar low, Davis Strait - visible imagery

Because of their high latitude, polar lows are at the periphery of the field of view of geostationary satellites. This is one of the few existing videos, and the viewing angle is not optimal. The cyclonic circulation is of mesoscale dimensions. The passage of the cold front is marked by a transition from a deeper stratiform cloud deck to shallow cloud streets.

Provided by CIRA.

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Feb, 22, 2020: South Pacific storm - visible imagery

Resembles a mature LC2 cyclone.

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December 30, 2020: Twin North Atlantic cyclones - Airmass RGB imagery

Two extratropical cyclones associated with baroclinic waves in the North Atlantic storm that develop more or less simultaneously. The airmass imagery shows the wrapping up of the rising (green) and descending (red) upper tropospheric air streams, as depicted schematically in Fig. 8.10 of the text.

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January 14-18, 2021: Pacific storms - precipable water imagery

In this sequence, the storms are following the climatological mean storm track from west to east across the Pacific and exhibit characteristics of LC1 baroclinic waves.

Provided by the NASA/Earth Observatory.

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October 10-25, 2021: Gulf of Alaska storms - precipable water imagery

A remarkable sequence of about five cyclogenesis events over the Northeast Pacific during the two-week interval October 10-25, 2021, as revealed by three hour images in the field of precipitable water derived from the GEOS5 data assimilation system. The storms are tracking southeastward along the coast of Canada.

Provided by NASA/GMAO.

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Jan 4-14, 2023: North Pacific storms - GeoColor imagery

During this 10-day interval, six or seven systems came ashore on the California coast. Some of them were old, decaying cyclones that reached their peak intensity days earlier when they were far out in the Pacific, and others were just developing. Such active periods occur only rarely.

Provided by CIRA.

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Feb. 24-28, 2023: Storms crossing US - GeoColor imagery

A high amplitude baroclimic wave develops over the North Pacific and passes over the western and central US, The first extratropical cyclone associated with it can be tracked as it crosses the Rockies, and a second cyclone develops over the Great Plains and reaches maturity over the Midwest.

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Feb. 24-26, 2023: Storm crossing California - GeoColor imagery

The same storm as the previous animation, viewed when it was coming ashore along the US west coast.

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March 9, 2023: Mid-Atlantic storm - GeoColor imagery

This storm exhibited a tight, rapidly rotating center. A rope cloud developed along the westward extension of the cold front in the subtropics. Open cell convection in the cold air mass assumed a variety of forms.

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March 13-15, 2023: US East coast storm — water vapor imagery

As the storm deepens, the cyclonic rotation of the low clouds becomes increasingly discernible. The center of the storm tracked northeastward at first and then curved northwestward into the Gulf of Maine.

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March 13, 2023. Cyclogenesis off Cape Hatteras - visible imagery

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March 14, 2023: Storm reaches New England coast - GeoColor imagery

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March 15, 2023: Storm reaches Nova Scotia - visible imagery

After executing a loop in the Gulf of Maine, the storm center started moving eastward and weakening, but it is still well defined in this sequence. The finestructure of the clouds is more clearly revealed in this high-resolution visible imagery.

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March 20-22, 2023: Overview of Pacific storm — water vapor imagery

The rapid development and short lifetime of the tight cyclonic circulation that came ashore near San Francisco is revealed more clearly in this continuous sequence based on water vapor imagery.

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March 21, 2023: Storm approaches California coast - GeoColor imagery

While the parent cyclone was stil spinning far offshore, a tight new center formed closer to the coast SSW of San Francisco.

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March 21, 2023: Closeup of storm coming onshore on CA coast - Visible imagery

The developing cyclone came ashore near San Francisco, with strong onshore winds to the south of it.

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March 26-29, 2023: Pacific storm — water vapor imagery

Shows a complex system with two successive cyclone centers that impacted the Pacific coast, from British Columbia to South California. Moist air rendered in blue shading, dry air in gray.

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March 27-29, 2023: Pacific storm - GeoColor imagery

A closeup of the second cyclone and its associated frontal bands.

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May 18, 2023: Storm over the Tasman Sea - multiple imagery

The first clip is based on visible imagery, the second on a combination of visible and infrared imagery, with higher clouds rendered less yellow. The third clip shows air mass RGB imagery. The fourth clip is a longer animation based on airmass RGB imagery, and the fifth is based on water vapor imagery.

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September 7-8, 2023: Storm over southeast Australia - water vapor imagery

The interleaving of moist, ascending and dry, descending airstreams, depicted schematically in Fig. 8.10 of the text, is illustrated by satellite imagery in one of the water vapor channels for this maturing cyclone over southeastern Australia on 7-8 September 2023. The dry, subsiding air stream is shaded yellow/red.

Provided by Andrew Miskelly / Weatherzone.

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Sept 26-27, 2023: Eastern Atlantic storm - GeoColor and Airmass RGB imagery

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October 28 - November 5, 2023: North Atlantic cyclones

1000-500 hPa thickness and SLP. Shows three successive intense cyclones evolving through their life cycles. The middle one, named Ciaran by the weather services, caused damaging winds and flooding in the British Isles and along the coast of northern Europe. The cusp in its thickness field can be tracked all the way across the Atlantic.

Provided by David Ovens.

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November 1-3, 2023: Northern Europe storm - GeoColor imagery

This early season, fast-moving, explosively-deepening cyclone, dubbed "Ciaran", passed through the English Channel, with a central pressure as low as 953 hPa, and into the North Sea, bringing hurricane force winds and floods.

GeoColor Meteosat imagery provided by CIRA.

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December 5-7, 2023: Gulf of Alaska storm

The first clip shows water vapor imagery: moist air rendered in blue shading, dry air in gray. This sequence is notable for the longevity of the frontal band, embroidered with mesoscale waves, which can be tracked for 36 h starting just after noon 12/03.

On 12/06, a second frontal band developed and moved ashore along the coast of the Pacific Northwest bringing heavy rain, while a comma cloud formed in the polar air stream west of northern California and tracked northeastward, acquiring a cyclonic circulation and an extended frontal band of its own.

The second clip shows the infrared window channel for just an 18 h interval. The mesoscale waves are more prominent and are seen to be present not just in the frontal band, but throughout much of the rain area. Some of the mesoscale banding over land is quasi-stationary — related to orographic features.

Provided by CIRA.

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Jan. 6-11, 2024: North America 500 hPa geopotential height

On Jan 7 UTC, a trough came ashore on the Pacific coast. On the 7th, it was positioned over the southwestern US, and on the 8th, it moved eastward began to deepen. By the end of the day, it developed a closed center that passed over the Texas Panhandle. The system achieved full maturity on the 9th, while passing over the Midwest, and it weakened on the 10th while crossing the northeastern US.

Provided by David Ovens.

(0:18)

Jan. 6-11, 2024: North America - 1000-500 hPa thickness and SLP

The structure of this system resembled that of a typical extratropical cyclone when it was out over the Pacific, but it fell apart as soon as the system moved inland, disrupted by the mountainous terrain. Late on Jan 7, the frontal zone developed a cusp over New Mexico. By 18 UTC Jan 8, the cusp was over Oklahoma and a surface low was discernible over the Texas panhandle.

Over the next 24 h, the system developed rapidly, feeding on the strong thermal contrast between the warm, humid air advected northward from the Gulf of Mexico and the cold, Canadian air advected southward in the west side of the low. By midnight Jan 10th, the surface low had stagnated and was beginning to weaken over Michigan, while the cusp on the frontal zone was moving on into New England.

Provided by David Ovens.

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Jan. 7-10, 2024: Central and eastern US storm - water vapor imagery

Throughout most of Jan. 7, the region of enhanced cloudiness over the southwestern US didn't have a well defined shape, but just before midnight, a frontal rain band developed over southeastern Arizona. This weak feature can be tracked for the next 24 h as it moved eastward across New Mexico and Texas.

By noon UTC Jan 7, a cyclonic circulation is apparent over the Texas panhandle, consistent with the development of the surface low in the previous video. Around 15 UTC Jan 7, a second rain band began to develop ahead of the original frontal band. By 06 on the 8th, the new rain band, which was ingesting warm. moist, boundary layer air from over the Gulf of Mexico, was becoming the primary rainband and the system was becoming reorganized on a larger scale.

By 15 UTC, low level clouds and moisture were wrapping around the surface low, bringing heavy snowfall to parts of Wisconsin and Iowa, while the frontal rainband, very strong by this time, was crossing the Florida panhandle.

Provided by CIRA.

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Jan. 9, 2024: Central and eastern US storm - Day Land Cloud imagery

This clip highlights the low clouds that produced snowfall over the Midwest, and the strong frontal rainband that crossed the eastern Gulf states.

Provided by CIRA.

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Jan. 9, 2024: Central and eastern US storm - Lightning

The frontal rainband of this system was marked by a well defined squall line, as evidenced by the distribution of lightning. Some of the thunderstorms crossing the Florida panhandle produced tornadoes. The first clip in this video shows GeoColor imagery, and the second shows visible imagery for the daylight hours.

Provided by CIRA.

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Jan. 9, 2024: Polar low, Ross ice shelf

VIIRS Snowmelt RGB imagery

Provided by CIRA.

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January 9-24, 2024: Clouds and precipitation

Generated by the GEOS5 data assimilation system. The sequence begins when a severe winter storm with a sharp frontal band. The Atlantic storm track was active, with five frontal cloud bands crossing the ocean during this 15 d interval. Because of blocking over the eastern Pacific, relatively few storms came ashore over western North America.

Provided by NASA SVS.

Provided by NASA SVS.

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January 9-24, 2024: 3 m temperature

As in the previous video, and also generated by the GEOS5 data assimilation system. The frontal zones are difficult to track over land because of the presence of the diurnal cycle and quasi-stationary features related to orography. Nevertheless, a number of well defined cold frontal zones are discernible: e.g., Jan 10-12 to the north of the Black Sea. Over the oceans the patterns are simpler, but they are weak because the 3 m temperature never departs more than a few degrees from the underlying sea surface temperature.

Provided by NASA SVS.

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January 16-17, 2024: Pacific / Oregon - Airmass RGB imagery

Suggestive of the rollup of a tropopause fold.

Provided by CIRA.

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January 20-21, 2024: Barents Sea - Visible imagery

A polar low.

Provided by CIRA.

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January 21-22, 2024: Atlantic and North Sea - Airmass RGB imagery

Storm named Isha. Brought hurricane force winds to parts of the British Isles.

Provided by CIRA.

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January 31-February 1, 2024: North Sea - IR window imagery

Storm named Ingunn.

Provided by CIRA.

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January 31, 2024: North Sea - Airmass RGB imagery

Named Ingunn. Minimum pressure 940 hPa, hurricane force winds on the coast of Norway

Provided by CIRA.

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January 31-February 7, 2024: Pacific / California - Water vapor imagery

A ten-day sequence showing two major storms, with a total of four strong frontal bands sweeping across California, bringing heavy precipitation.

Provided by CIRA.

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January 30, 2024: Pacific / California - GeoColor imagery

Provided by CIRA.

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January 30-31, 2024: Pacific / California - Mid tropospheric water vapor imagery

Provided by CIRA.

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Vertically propagating gravity waves over the Pacific Northwest, February 14-28, 2024 - GeoColor imagery

As the cloud band crossed the coast range, the Cascades, and the Rockies, it developed a distinctive orographic signature suggestive of vertically propagating gravity waves.

Provided by CIRA.

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LC1 θ_surf

The surface θ field, indicated by the intensity of the orange shading for LC1. Contour interval 5K.

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LC2 θ_surf

The surface θ field, indicated by the intensity of the orange shading for LC2. Contour interval 5K.

(0:09)

LC1 θ_surf and p_s

The surface θ field, indicated by the intensity of the orange shading, and the surface pressure field, indicated by the contours (interval 5 hPa), for LC1.

(0:09)

LC2 θ_surf and p_s

The surface θ field, indicated by the intensity of the orange shading, and the surface pressure field, indicated by the contours (interval 5 hPa), for LC2.

(0:09)

LC1 ω₇₀₀ and θ_surf

Vertical velocity at sigma = 0.7 in sigma coordinates, roughly equivalent to the 700 hPa or 3 km level, indicated by colored shading (blue corresponds to ascent and warm colors to descent). Velocities are superimposed upon potential temperature along the bottom boundary, contour interval 5K. For LC1.

(0:09)

LC2 ω₇₀₀ and θ_surf

VVertical velocity at sigma = 0.7 in sigma coordinates, roughly equivalent to the 700 hPa or 3 km level, indicated by colored shading (blue corresponds to ascent and warm colors to descent). Velocities are superimposed upon potential temperature along the bottom boundary, contour interval 5K. For LC2.

(0:09)

LC1 θ (PV2) and θ_surf

The θ field on the PV=2 surface in contours (interval 10K), which corresponds to the dynamic tropopause, and the surface θ field for LC1 in color shading (interval 5K).

(0:09)

LC2 θ (PV2) and θ_surf

The θ field on the PV=2 surface in contours (interval 10K), which corresponds to the dynamic tropopause, and the surface θ field for LC2 in color shading (interval 5K).

(0:09)

LC1 PV(300) and θ_surf

PV on the 300K isentropic surface, indicated by the color shading (interval 0.25 PVU), and the surface θ field, indicated by the contours (interval 5K), for LC1.

(0:09)

LC2 PV(320) and θ_surf

PV on the 320K isentropic surface, indicated by the color shading (interval 0.25 PVU), and the surface θ field, indicated by the contours (interval 5K), for LC2.

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Vertical velocity and temperature: weak convection

In this run, the relative humidity is set to a value that yields weak convective heating.

(Left) Vertical velocity (colored shading, scale in m s^-1) and temperature (contour interval 5 K) at the 3 km level.

(Right) Vertical cross section along the green line in the left panel following the same conventions for contours and shading. The vertical velocity field is dominated by the synoptic scale fields consistent with quasi-geostrophic dynamics, but weak gravity waves on a much smaller scale are discernible toward the end of the animation.

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Vertical velocity and temperature: strong convection

As in the previous animation, but in this run the relative humidity is set to a value that yields much stronger convective heating in the model. The evolution is similar to the previous one but the gravity waves are seen to be correspondingly stronger.

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Horizontal divergence and scalar wind speed: weak convection

Horizontal divergence Div and scalar wind v fields in a developing baroclinic wave.

(Left) V at the 8 km level and Div at the 12 km level in units of in units of 10^-5 s^-1 and (right) in a meridional cross-section oriented along the green line in the left panel. Contour interval for V is 5 m s^-1: the westerly jet is initially located between the two middle contours.

Gravity waves are much more prominent in the left panel in this animation than in the one for the mid-tropospheric vertical velocity field (8.1-30) because the 12 km level is in the lower stratosphere, where the static stability is quite strong. The synoptic scale ageostrophic wind field is largely confined to troposphere and lowermost stratosphere, while the gravity waves disperse upward, their amplitude increasing with height in the absence of dissipation.

(0:14)

Potential vorticity, scalar wind speed, and potential temperature: weak convection

(Left) Potential temperature (red, contour interval 5 K), wind speed (black, contours at 40, 45, 50 and 55 m s^-1), and potential vorticity (color shading; scale in PVU), all at the 5 km level.

(Right) Cross section along the green line in the left panel following the same conventions for contours and shading except that wind speed contours are 30, 35, 40, 45, 50, 55, 60 and 65 m s^-1. As the waves amplify, a fold on the tropopause develops in which ozone and other stratospheric tracers descend into the troposphere, as described in Section 9.2.3 of the text.

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May 8. 2003: Webcam, University of Zurich

Buoyant updrafts in deep convective clouds over southern Germany ascending into the lower stratosphere and mixing with the environmental air at that level, before they become obscured by the anvil clouds that develop at the tropopause level.

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June 28, 2018: US Great Plains - visible imagery

Overshooting plumes visible above the anvils of mesoscale convection. Based on NOAA geostationary satellite imagery with 3 minute time resolution.

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December 10, 2018: Overshooting cloud-top in storm over Argentina

Based on NOAA geostationary satellite imagery with 3 minute time resolution.

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February 6, 2018: A tropopause fold wrapping up into a cyclone - Airmass RGB imagery

The band of strong cyclonic shear in a tropopause fold is rendered conspicuously red in this airmass imagery by virtue of the high ozone concentration, and the dryness of the air at the jet stream level within the descending air in the tropopause fold. The lobe on the western end of the fold wraps up into a tight cyclonic vortex, with the characteristics of an extratropical cyclone in a fully developed baroclinic wave.

Provided by CIRA.

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u, v, w, T climatology

The seasonally varying stratospheric climatology, as in Fig. 9.8 in the text but animated. Temperature, the departure from the global mean, is indicated by the colored shading and zonal wind by contours at 5 m/s intervals. Mean meridional circulations are indicated by the arrows. The meridional circulations in the stratosphere are much weaker than in the troposphere, so the scale is adjusted to make them more clearly visible. The break in the scaling is at 100 hPa. The year is repeated four times. Based on ERA5. Provided by Hamid Pahlavan.

(1:01)

Noctilucent clouds, January 17, 2024 - Atmosphere RGB imagery

Around the periphery of the summertime polar cap, where the sun dips below the horizon at night, clouds that form in the layer of ascent at the level of the mesopause (80 km) remain illuminated, while the troposphere is in deep twilight, and are visible despite their very small mass per unit area. This video confirms that they are distinct from the clouds at lower altitudes.

Provided by CIRA.

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Noctilucent clouds (still image), June 12, 2019

Provided by the NASA Earth Observatory.

Tropical tape recorder seen in specific humidity

Companion to Fig. 9.9 showing a time-lapse, pole-to-pole meridional cross section based on the ERA5 water vapor climatology. The meridional extent of the signal is surprisingly broad. Provided by Hamid Pahlavan.

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Northern Hemisphere 2009: PV on the 850 K surface and 25 hPa height

This relatively old video is a companion to Fig. 9.14 in the text. It shows the breakdown of the Northern Hemisphere polar vortex in January 2009. In this group of videos, it is the only one that shows the evolution of the geopotential height field. The shaded field is PV on the 850K surface and the contour interval for the 25 hPa height field is 250 m. Provided by Noboru Nakamura.

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Northern Hemisphere PV, 7 hPa (34 km), 2012-2013

Provided by Lawrence Coy and Steven Pawson, NASA GMAO.

(1:08)

Southern Hemisphere 2002: Water vapor on the 850 K surface

Based on the ERA5 Reanalyses. Copyright ECMWF. Provided by Adrian Simmons.

(1:36)

Southern Hemisphere 2002: PV on the 850 K surface

Based on the ERA5 Reanalyses. Copyright ECMWF. Provided by Adrian Simmons.

(1:36)

Southern Hemisphere 2002: ozone mixing ratio on the 700 K surface

Based on the ERA5 Reanalyses. Copyright ECMWF. Provided by Adrian Simmons.

(1:36)

September 2019: Stratospheric wave train

PV at the 7 hPa (34 km) level. Wave packet developing along a front that separates high PV air originating in the polar vortex and low PV tropical air. Waves form on the eastern side of the packet and break on the west side.

The field is derived from a 10-day forecast using an experimental high-resolution model. Provided by the NASA/GMAO.

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Transport of stratospheric ash from the Tonga eruption, January 15-19, 2022

This video follows the stratospheric ash cloud that emerged from the Tonga eruption, rendered in light green, as it drifts, west-northwestward and then due westward across the Indian Ocean in the equatorial belt over a 4 day interval. That the cloud remains remarkably coherent as it drifts suggests that the winds are predominantly zonal, steady, and organized on a planetary scale. The shape of the could toward the end of the video is suggestive of the existence of an easterly wind speed maximum along the equator.

Provided by Andrew Miskelly / Weatherzone.

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QBO zonal wind anomalies

Evolution of the QBO zonal wind anomaly field over the 10-year period of record 2008-2017. Contour interval 5 m/s. Provided by Hamid Pahlavan

(1:22)

QBO temperature anomalies

Evolution of the QBO temperature anomaly field over the same 10-year period of record 2008-2017. Contour interval 1 K. Provided by Hamid Pahlavan

(2:45)

QBO raw u, v, w, T for 1979-2018.

Evolution of the QBO total fields over the 40-year period 1979-2018. ([v], [w]) plotted as vector. In the stratosphere the mean meridional circulations are much weaker than in the troposphere, so the scale is adjusted to make them more clearly visible. The break in the scaling is at 100 hPa. The contour interval for [u] is 5 m/s. Provided by Hamid Pahlavan

(8:06)

Composite QBO cycle in zonal wind and temperature in ERA-Interim Reanalysis (1979-2018).

Composite QBO cycle. [T] anomalies indicated by colored shading, at 0.5 K intervals; [u] anomalies indicated by contours at 5 m/s intervals. Provided by Hamid Pahlavan

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Kelvin wave, n = –1

Companion to Fig. 10.10 in the text.

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MRG wave westward propagating n = 0

Companion to Fig. 10.11.

(0:30)

MRG wave eastward propagating n = 0

(0:30)

Rossby wave n = 1

(0:30)

Rossby wave n = 2

(0:30)

Gravity waves on a free surface

Height and wind fields in external gravity waves emanating from a point height anomaly in a shallow water wave equation model with a resting basic state and no rotation.

Provided by Daniel Vimont.

(1:11)

Gravity waves on a free surface: a laboratory example

The waves are dispersing outward from a drain in a tank of water.

Provided by Brian Mapes.

(0:17)

Internal gravity waves in a fluid with uniform stratification

Wave response to an oscillating plunger in a uniformly (stably) stratified fluid. The plunger is turned on at the beginning of the animation. The colored shading represents the temperature (or buoyancy) perturbations. The diagonally shaped waveguide configuration is referred to as St. Andrew’s cross.

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Gravity waves in a fluid with uniform stratification - closeup.

As as in the previous video, but zoomed in on the upper right quadrant of the cross configuration. The colored shading represents the temperature (or buoyancy) perturbations and arrows represent the winds.

(0:17)

Ash cloud - visible imagery

To fully appreciate this video, it is necessary to download it and advance it manually so it can be viewed frame by frame. The 10 minute interval between frames is too long to clearly reveal the wave propagation, but concentric rings, indicative of gravity waves propagating out from the eruption are apparent is many of the frames.

In Frame 5, a concentric ring of enhanced brightness of the low clouds is discernible to the west and northwest of the ash cloud, and it can be followed in Frames 6 and 7 as it propagates outward. In Frame 6, a gray circular disk emerges from beneath the ash cloud. Circular rings are apparent in the top of the ash cloud itself, but they are irregular and difficult to follow.

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Ash cloud height - stereoscopic imagery

Created by combining data from the Himawari-8 and GEOS-17 satellites. The cloud reached a peak height of 58 km about 30 min after the eruption. The cloud layer at the level of the tropical cold point is also visible to the east of the higher cloud. Early in the video, rings of gravity waves can be seen propagating out from rising fumes.

Provided by the NASA Earth Observatory.

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IR window channel

The color shading reveals the height of the anvil (colorbar at bottom of image). By Frame 4, about 40 minutes after the eruption, the cloud top has reached ~50 km (blue shading). From Frame 9 to 10, a lower, colder cloud deck, indicated by the red and black shading, had formed upwind, to the east of the ash cloud. The banding transverse to the flow in this cloud is associated with quasi-stationary gravity waves, on a scale much smaller than that of the radially propagating waves.

(0:07)

IR window channel - zoomed out

As in the previous video, but zoomed out so that a meandering line of convection to the north and east of Tonga is included. In this version, both the internal and external gravity waves emanating from the explosion and eruption are clearly distinguishable, and a strong convective cell is seen to develop about 2000 km due east of Tonga. Gravity waves originating in the cell are visible, even in the unfiltered data.

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Filtered water vapor imagery

Zoomed in version of 2.9-2. Water vapor imagery in the 7 μm band, high pass filtered in time to reveal the most rapidly evolving features and rendered in a gray scale. The external and internal waves are clearly distinguishable by virtue of their much different phase speeds. Long after the external wave from the explosion exits the area, internal waves continue to be excited by the ongoing eruption.

Provided by Mathew Barlow.

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SST, Aghulas Return Current region

Long lived eddies and meanders in the SST field in the Aghulas Return Current region. The variability is especially strong along its poleward flank. This video spans the three year period 2011, 2012, and 2013. Provided by the NASA/SVS Animations of Gulf stream meanders and eddies, which can be viewed here.

(1:50)

SST and wind speed, Aghulas Return Current region

Monthly mean fields of spatially highpass filtered surface wind speed based on scatterometer data, indicated by colored shading; and SST from AMSR, contour interval 1 K, for the period 2003-2009. Note the strong correspondence between the two fields.

Provided by Dudley Chelton.

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SST and wind speed, Gulf Stream region

As in the previous video. Provided by Dudley Chelton.

(0:10)

Unfiltered 500 hPa height, November 2007- March 2008

Frames at 6-hour intervals, contour interval 50 m. Baroclinic waves impart a pervasive sense of eastward propagation, but quasi-stationary and retrograding (westward propagating) features are evident as well. Isolated height maxima within the polar vortex, (i.e. poleward of the strongest westerlies) are indicative of anticyclonic vortices. Isolated minima equatorward of the strongest westerlies, (i.e. cutoff lows) are indicative of cyclonic vortices. The strongest westerlies often correspond roughly to the 555 dkm contour, indicated by the darkest red.

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High-pass and low-pass filtered 500 hPa height, December 2007- February 2008

Frames at 6-hour intervals. Colored shading indicates highpass filtered, and contours indicate lowpass filtered fields. Contour interval for the lowpass filtered field 50 m. Note how the evolving lowpass filtered fields act as a "steering flow” for the high pass filtered perturbations.

(1:01)

Lowpass filtered 500 hPa height, October 2007 - March 2008

Contour interval 50 m.

(0:57)

Unfiltered 500 hPa scalar wind speed, August 1 - November 30, 2006

Scalar wind speed at the 500 hPa level (in knots). Based on data obtained from the GEOS data assimilation system: maps at 1 hour intervals.

Provided by the NASA/SVS.

(1:38)

Rossby wave packets

Wave activity dispersing eastward in Northern Hemisphere baroclinic wave packets during 29 Jan - 12 Feb, 2009. The brown contours are 300 hPa geopotential height, contour interval 300 m. Shading indicates Rossby wave packet envelopes in units of m/s, obtained using Hilbert transform applied on meridional velocity perturbations following Zimin et al. (2006). The RWP tracking was developed by Matthew Souders (see Souders et al. 2014). Provided by E. K-M Chang and Brian Colle.

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Mesoscale ocean eddies I

Sea surface height (SSH) anomalies in the eastern North Pacific Ocean, as revealed by satellite altimetry during the 51-month period (September 2002 through November 2006). The eddies drift westward, with a slight poleward deflection of cyclones and equatorward deflection of anticyclones. During the last 14 months of the animation (from 17 August 2005 onward), the rotating trajectory of a subsurface float at a depth of about 350 m is overlain on the SSH field. A detailed global analysis of altimeter measurements of mesoscale ocean eddies can be found in Chelton et al. (2011). Provided by Dudley Chelton.

(0:18)

Mesoscale ocean eddies II

Global sea surface height (SSH) anomalies as revealed by satellite altimetry during the 10-year period (August 1996 through August 2006). The eddies drift westward, with a slight poleward deflection of cyclones and equatorward deflection of anticyclones. A detailed analysis of these altimeter measurements of mesoscale eddies can be found in Chelton et al. (2011). Provided by Dudley Chelton.

(0:22)

South America I

In the first clip, a wintertime cold front / surge moving northward on the east side of the Andes June 10, 2017 dissipates a deck of low clouds as it passes. In the second clip, the gust front of an advancing cold surge triggers a massive dust storm over Argentina December 18, 2020. In the third clip, a northward moving cold surge that originated in the Southern Hemisphere suppresses shallow daytime convection over the lowlands near the mouth of the Amazon Oct, 23. 2017).

In the fourth clip, lightning is superimposed upon GeoColor imagery. A summertime cold surge gives rise to several squall lines as it propagates northward along the eastern slope of the Andes, where the convective available potential energy (CAPE) is sufficient to support deep convection.

Provided by CIRA.

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South America, February 11-12, 2024

Provided by CIRA.

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New Mexico and West Texas, Oct. 30, 2017

The frontal boundary appears to be on the verge of dispersing into a train of gravity waves.

Provided by CIRA.

(0:06)

Texas, Jan. 14, 2021

NOAA GOES 16 satellite imagery in the 6.2 μm (water vapor) channel. Surface wind barbs and temperature are also shown. The green and white-shaded areas are moist, the blue-shaded areas dry.

The front, with northerly winds behind it, first becomes discernible around 07 UTC as it propagates southward through southern Colorado and Kansas. By 09, it has crossed the Texas border at the top pf the panhandle and by 1430, it has reached the base of the panhandle on the New Mexico side. Note the wind shifts as it passes the weather stations.

Provided by NOAA/CIMSS.

(0:23)

Low cloud signatures: Rockies

The flow behind cold fronts propagating southward along the lee slopes of the Rockies exhibits a strong upslope component. The air behind the advancing cold front is often lifted to its lifting condensation level, giving rise to a deck of low clouds or fog, which serves as a marker for the front in the satellite imagery.

In parts of the second and third clips of this video, the frontal passage (i.e., the wind shift and the beginning of the temperature drop) precedes the arrival of the fog or low clouds by an hour or two. The dates of the clips are Nov. 7, 2019, Feb. 20, 2018, and Feb. 3, 2020, respectively.

Provided by CIRA.

(0:42)

New Zealand: surface winds and temperatures

Surface winds (arrows) and temperature (colored shading) associated with a cold front passing over the South Island of New Zealand—the conspicuously cold feature. The frontal zone was deformed by the Alps: the cold air was advancing on both sides of the mountain island, but on the eastern side, its leading edge assumed the form of a sharp cold front accompanied by strong surface winds. In this part of the world, cold surges are popularly referred to as “southerly busters”.

Provided by Meteorological Service of NZ Ltd.

(0:15)

Wellington, New Zealand, time lapse camera

The camera is pointing towards the south-southeast. As the front approaches, its passage is attended by an arcus cloud, a burst of strong southerly winds, a rapid SLP rise, and a transition to showery weather.

Provided by Meteorological Service of NZ Ltd.

(0:35)

Southeast Australia: signature in wildfire smoke

Doppler radar observations of velocity of smoke particles reveal the windshift line associated with a southerly buster passing Sydney (SYDN), 21 December, 2019. As it propagates northward beyond Sydney, the front-like feature disperses into a train of gravity waves.

Provided by Andrew Miskelly / Weatherzone.

(0:09)

A sample animation

One of the 184 videos in the one point correlation library: SLP on the 40°N latitude circle during DJF. The PNA and NAO patterns are clearly evident. The rest of the animations can be found here.

(0:24)

2007-2008 winter

Provides several examples of blocking over Alaska, The first major episode, which began around Nov. 20 and lasted about two weeks, temporarily split the polar vortex into eastern and western lobes.

The Jan 15-25 episode was more typical of Alaska blocking events. The block remained more for less in place, while a series of short (baroclinic) waves propagated through it, their troughs depressing the crest of its ridge and their ridges amplifying it as they come into alignment with it. Northern Europe between December 12-20 experienced a classical “omega block”, or “modon" pattern, with an anticyclonic gyre over the Norwegian Sea and a cyclonic gyre directly to the south of it over the Mediterranean. It is notable that no high amplitude blocking events occurred over Greenland during this winter.

Provided by David Ovens.

(0:51)

2009-2010 winter

Blocking over Scandinavia occurred several times during early winter. High amplitude blocking events occurred over or near Greenland on Dec. 11-23, Dec. 29-Jan 5, and March 25-29. Throughout much of the winter, geopotential height over Greenland was well above normal. Several notable examples of Alaska blocking also occurred during this winter.

Provided by David Ovens.

(0:50)

Marine layer surges landward

A marine stratus deck coming ashore just before sunset at Scripps Institute of Oceanography on the coast of southern California. It exemplifies the characteristic of the pervasive and expansive layers of low clouds in the subtropical subsidence zones. Taken at an altitude 62 m. The northward propagating undulations along the leading edge of the cloud deck are suggestive of gravity waves.

Provided by Pengcheng Zhang.

(0:14)

Clouds in the SSZ cloud decks

The coverage of low clouds is extensive within the SSZs. The clouds exhibit a wide variety of forms — networks of cells predominate, but dendritic structures are also observed from time to time. Gravity waves modulate the cloud albedo and, because of the strong stratification, islands and irregularities in the shape of the coastline leave wakes extending far downstream, often characterized by von Karmann vortices.

This animation is made up of a series of short clips. In the first two, the cells are organized into low level cyclonic vortices. In the third and fourth clips, strong von Karman vortices develop behind what appears to be a downwelling Kelvin wave and gradually spin down. The fifth clip is similar, but the downwelling wave is advected by the background flow faster than it propagates. The von Karman vortices in the remaining clips are in the wakes of islands.

Provided by CIRA and CIMMS. By downloading the video and advancing it manually, it is possible to view the clips one-by-one.

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Evolving form of SSZ cellular convection (December 1, 2021)

Provided by CIRA.

(0:03)

Global SST, March 2007-February 2009

Daily SST fields from the Advanced Microwave Scanning Radiometer . The color scale is latitude dependent and designed to reveal the structure at tropical latitudes. See Chelton et al 2005.

Provided by Dudley Chelton.

(0:30)

Related variations in surface wind stress, July 27 - 1 November 10, 1999

Top panel, SST from TMI. Middle panel, curl and the bottom panel, the divergence of the surface wind stress, based on Quikscat (satellite-borne scatterometer) data. Note the elongated patches of divergence (indicated by red shading in the bottom panel) over the equatorial SST front. For further discussion, see Chelton et al. (2001).

Provided by Dudley Chelton.

(0:25)

November 23-24, 2023

Two different renditions of the same events, covering a 13 h interval from evening to morning. Lightning strikes, shown in both renditions, reveal the convective cores from which the waves originate.

The first rendition shows the signature of two distinct wave trains in the low clouds, which is dominated by a single wave, sometimes referred to as a roll cloud or bore. Its passage is marked by downwelling and subsidence warming, resulting in the disappearance of some of the marine cloud decks. The circular symmetry of the fsrst bore is quite impressive.

The second rendition, which begins after a short pause, shows water vapor imagery and the tops of the deep convective clouds in which the clusters of intense lightning are embedded. The water vapor imagery reveals the wave trains much more clearly. Intersecting wave trains pass through one another without interacting.

Provided by Andrew Miskelly / Weatherzone.

(0:15)

Further examples

As in the previous animation, but shorter sequences focusing on the generation of the waves in two different events.

Provided by Andrew Miskelly / Weatherzone.

(0:10)

Gravity waves radiating outward from a drain in a tank

Provided by Brian Mapes.

(0:17)

External gravity waves from a point source

Height and wind fields in gravity waves emanating from a point height anomaly in a shallow water wave equation model with a resting basic state and no rotation. Provided by Daniel Vimont.

(1:11)

Internal gravity waves from a point source

Simulation of convectively generated gravity waves using NCAR's Complex Geometry Compressible Atmospheric Model (CGCAM). Latent heating is used as a proxy for convection.

(Left) a cross-section at a height of 85 km. (Right) vertical cross-section through the center of the domain. Shading indicates vertical velocity perturbations. The solid thin line depicts the background zonal mean wind profile. Created by C. Heale and provided by Jadwiga Richter.

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Simulated gravity waves generated by deep convection

Simulated convectively forced gravity waves in a 2D model. Flow from right to left relative to the cell. Part 1: horizontal motion field in the plane of the cross-section: purple shading indicates flow toward the left and green flow toward the right. Part 2 shows vertical velocity: green shading for ascent and purple for descent. In both parts of the video, the contours indicate the isentropes and the bold black lines indicate the outlines of the convective cloud.

Provided by Dale Durran.

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WRF Model

Shows the evolution of the vertical velocity field w at 50 km over the western Pacific in the full-physics Weather Research and Forecast (WRF) model, with 3 km grid-spacing. Initialized at 00 UT 2 Aug 2 2016, based on ERA5 fields with 28 km resolution. In the first few frames, convection triggered by land-sea breeze circulations excites gravity waves, discernible as circular rings. Starting around frame 20, waves emanating from convective cells over the open ocean are also evident, and the field becomes increasingly complex.

Provided by Y. Qiang Sun.

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Mesospheric gravity waves from Hurricane Otis (still image)

12-hour forecast of geopotential height at the 0.01 hPa (~70 km) level at the time when Hurricane Otis was making landfall on the coast of Mexico, with the NOAA/ NWS GFS model, initialized at 00 UTC, 25 Oct 2023.

No rotation

Shows the evolution of clouds and humidity in a cloud-resolving model simulation in a doubly periodic 768 km by 768 km cartesian domain. Gray shading indicates the presence of clouds, and color shading indicates the water vapor mixing ratio near the surface, blue for drier, warm colors for more moist. Surface temperature and insolation are uniform and there is no rotation. The model used is the System for Atmospheric Modeling, v6.8.2 (provided and maintained by Marat Khairoutdinov). Provided by Allison Wing and Ryan Abernathey.

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On an f-plane

As in the previous video, but on an f plane where f = 2 x 10^-4 s^-1. Gray shading indicates the presence of clouds, and the colored shading indicates the low level humidity field: here, blue shading denotes moist and yellow shading denotes dry. The presence of rotation leads to the formation of a vortex that bears some resemblance to a tropical cyclone, but its circulation fills the entire domain.

An additional numerical simulation with equatorial β plane geometry has been performed by Carstens and Wing (2023) (doi:10.1175/JAS-D-22-0222.1). In this case, a Kelvin wave regime prevails within 10-15 degrees of the equator and a regime characterized by numerous small, coexisting cyclones prevails at higher latitudes.

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IMERG precipitation climatology

Seasonally varying precipitation climatology based on IMERG data from NASA’s Global Precipitation Mission. 30-d running means. Best viewed by manually controlling the calendar date. All the features discussed in this chapter, such as the sudden transitions as well as the more gradual sinusoidal variations, are discernable in this video.

Provided by NASA/SVS.

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June 15-16, 2018: Okinawa - Infrared imagery

Okinawa at 26°N is the island on the left of the image, about halfway between top and bottom. Infrared imagery in the water vapor channel from the Himawari 8.

Provided by the Japanese Meteorological Agency (JMA).

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July 5-8, 2018: Honshu - Infrared imagery

South Korea at upper left; Kyushu and Honshu below and to the right. Infrared imagery in the water vapor channel from the Himawari 8 satellite.

Provided by the Japanese Meteorological Agency (JMA).

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July 5-8, 2018, Honshu - Radar and water vapor imagery

Rain rate in units of mm/h in the intense convection, indicated by the colored shading. (When the video is expanded to full screen, a colorbar appears along then bottom.) The gray shading in the background is water vapor imagery. Lighter shading indicates higher moisture.

The front causes widespread stratiform precipitation, indicated by the blue shading, as well as heavier convective precipitation, indicated by the brighter colors. The convective dells are elongated, aligned with the flow and anchored in place by the orography. The rain that fell in this system produced widespread flooding and landslides, especially near the Inland Sea.

Satellite imagery produced by the Japan Meteorological Agency (JMA) and provided by the Research Institute for a Sustainable Humanosphere at Kyoto University.

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Summer 2018: Polar and subtropical jets - 925 hPa temperature anomalies

Selected geopotential height contours, as indicated, showing the locations of the polar and subtropical jets. During the Baiu heavy rain episode (July 5-8), a trough in the subtropical jet was located upstream of Japan. Toward the end of the event, the subtropical gel over east Asia began moving northward, and it remained well to the north of its climatological mean position for the next several weeks.

Provided by Hisashi Nakamura.

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July 2, 1995: South Florida - Visible imagery

ESummer thunderstorms over South Florida. The animation begins at 0700 LT. During morning hours, shallow convection is prevalent. A seabreeze front forms along the Atlantic coast. Around noon, the first deep cell forms along the seabreeze front, and additional cells develop during early afternoon. Each cell reaches maturity within 3 hours after it forms. Notable features in this animation are the gust fronts (gravity currents) emanating from the bases of the downdrafts, which retain their identity for several hours after they first become discernible.

Provided by NASA / GSFC.

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July 17-27, 2021: North America - Water vapor imagery

Provided by NOAA’s Cloud and Moisture Imagery Project.

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South America - IR window imagery

The first clip shows mesoscale convective complexes over northern Bolivia (February 22, 2018), and the second shows convective storms over Argentina (February. 17, 2020). Note that in both clips, the planetary scale circulation at the cloud top-level is anticyclonic. IR imagery.

Provided by CIRA.

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December 1, 2023: South America - IR window and lightning location imagery

Follows a mesoscalescale convective system from sunrise to sunset local time, as it moved northward behind a slow moving cold front. New cells formed on the western side off the complex and matured as they were advected eastward. Boundary layer air was continually being drawn into the system from the north side. Argentina is on the left side of the image, and Uruguay on the right.

Provided by CIRA.

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Jan. 15-17, 2024: Northern Australia - GeoColor imagery

Deep convection in the presence of a weak, slow moving cyclone. The circulation advects the cloud anvils, but in this case, it doesn’t seem to have much effect upon the organization of the cells.

GeoColor imagery provided by CIRA.

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August 16, 2002: Arizona, onset of deep convection

Looking SSE from Tucson, Arizona toward Mt. Lemmon, 0900-noon local time. Updrafts in shallow cumulus clouds reached the level of free convection early in the morning, but their vertical development was inhibited by the entrainment of dry air. As they moistened the lower troposphere, they deepened into towering cumulus. Eventually several of them merged to form the updraft of a much deeper cumulonimbus cloud, which developwand matured during the final hour of the sequence.

Provided by Joseph Zehnder. For further specifics see Zehnder et al. (2006).

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Arizona: Updrafts

This series of clips shows buoyant updrafts, many of which rise to their equilibrium level near the tropopause. The more vigorous ones spread out to form anvils. The time lapse imagery was taken at different times of day and is played at various speeds.

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Arizona: Downdrafts

This complementary series of clips shows examples downdrafts that develop in most convective storms as they mature. In the storms shown in Part I. the negative buoyancy of the downdrafts is due to evaporative cooling by falling raindrops. The downdrafts exhibit a lighter shade of gray than the updrafts, and the shading is more uniform because the cloud case is insured by falling raindrops, Some of these clops show arcus clouds along the interface between updraft and downdraft, whose rotation derives from the vertical shear between the evaporatively cooled outflow from the downdraft and the warmer inflow into the updraft. In the storms shown in Part II, the updrafts are more local and much more intense, driven by the weight of the falling rain and hail.

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November 2008

Visible imagery with lightning locations.

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October 22-25, 2020: Australia - Lightning locations

Follows an active springtime system as it moved eastward during a 4-day period. Many of the lightning flashes are arrayed in the form of squall lines, which tend to form during the afternoons. The blue shading marks the areas that had experienced thunderstorms since the beginning of this interval.

Provided by Andrew Miskelly / Weatherzone.

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March 17, 2021: Southern US - Airmass imagery with lightning

Successive squall lines accompanied by frequent lightning, developed in a tropical airmass along and ahead of a cold front in a mature extratropical cyclone passing over Texas and onward into the Gulf states.

Provided by CIRA.

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March 16, 2023: Central US - Visible imagery with lightning

A well defined squall line, marked by a narrow "rope cloud”, is visible (top center) at the beginning of the clip. During the next few hours, this system weakens as it passes over southern Oklahoma, while convective cells farther to the east show signs of falling into a new line.

Provided by CIRA.

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May 20, 2023: Central US - Visible imagery with lightning

A "rope cloud" developed in relatively shallow convection in early morning over east Texas. By noon, the convection along the line had deepened, as evidenced by the widespread anvil clouds. During the afternoon, lightning became increasingly frequent along the line.

Provided by CIRA.

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August 7, 2023: US Middle Atlantic states - Visible imagery with lightning

Provided by CIRA.

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September 9, 2023: SE Australia - Visible imagery with radar and lightning

Provided by Andrew Miskelly / Weatherzone.

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December 19, 2023: Australia - GeoColor imagery

Note the arc clouds propagating westward from the convection.

Provided by CIRA.

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US Great Plains - Ground-based imagery

This animation is made up of 12 clips, each showing a short time-lapse segment from a different storm.

Provided by Alex Schueth. Some of the full length videos from which these clips were extracted can be viewed on social media sites, and there are other videos as well.

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Monthly global SST anomalies, 1982-2017

Makes a compelling case for the existence of ENSO. The animation of the monthly averaged SST is coupled with an evolving time series of Nino 3.4. The manual control enables the viewer to view the contrasting SST patterns during El Niño and La Niña. Based on the Optimum Interpolation (OI) SST version 2 dataset produced by NOAA, derived from a blend of satellite data and marine surface observations from ships of opportunity.

Provided by the NASA/SVS.

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5-month running mean SST anomalies, 1982-2017

As in the previous animation, but smoothed by applying a five month running mean to the SST fields before making the animation. The ENSO-related variability stands out much more clearly in the smoothed fields.

Provided by Xianyao Chen.

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5-month running mean SST anomalies, 1910-2017

Gridded SST fields based on marine surface observations alone extend back in time much farther than those based on OI. This animation documents the history of ENSO extending back to 1910 based on NOAA’s Extended Reconstruction of SST (ERSST), version 5.

Provided by Xianyao Chen.

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Sea surface height anomalies, 1997 and 2015

Shows the development of El Niño events during calendar years 1997 and 2015, as manifested in the sea surface height field as sensed by satellite altimetry, as in the bottom panel of Fig. 17.9 in the text. The year-long sea level increase along the equator in the eastern Pacific is punctuated by several eastward surges of warm water, which are attributable to the passage of equatorial Kelvin waves.

Provided by NASA/SVS.

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Clouds over the Indian Ocean, April 29-May 13, 2002 - IR imagery

Shows a region of enhanced convection associated with the MJO propagating eastward across the Indian Ocean. Rather than a single "supercluster”, it assumes the form of multiple cloud clusters of various shapes and sizes, including a tropical cyclone pair.

Provided by NOAA/CIMSS.

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Geopotential height

Evolution of global fields of geopotential height anomalies through one complete cycle of the MJO. The SLP field by colored shading and the upper tropospheric (100-300 hPa) field is indicated by the contours.

Provided by Angel Adames.

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Surface winds winds over the Marine Continent

ERA5 10 m surface winds composited on the basis of the OMI index. Note how the MJO signature is channeled by the islands into a narrow band just to the north of Australia..

Provided by Pragallva Barpanda.

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Column water vapor over the Marine Continent

Composite ERA Interim column water vapor (precipitable water) based on the OMI index (Kiladis et al., 2014), data for all calendar months. The contoured field is OLR. Like the surface wind signature, it is channeled by the islands into a narrow band just to the north of Australia.

Provided by Pragallva Barpanda.

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Column water vapor over the Indo-Pacific warm pool

Composite ERA Interim column water vapor (precipitable water) based on the OMI index (Kiladis et al., 2014), data for all calendar months. The contoured field is OLR. The anomalies propagating eastward across the Indian Ocean are centered a few degrees north of the equator, but when they reach the Marine Continent, the center shifts to ~10°S.

Provided by Pragallva Barpanda.

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February 15-17, 2023

A winter cyclone that moved slowly westward through the Hawaiian Islands brought an extended episode of heavy rainfall, along with snow and record low temperatures (-11°C) on the summit of Mauna Kea. GeoColor imagery.

Provided by CIRA.

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Hurricane Larry track

MODIS imagery

An overview of the clouds, rendered much as they appear in visible imagery. The low level cyclonic inflow is delineated by the motion of shallow convective clouds, and the high level outflow by the motion of the cirrus filaments emanating from the anvils of deep convective clouds, which is predominantly anticyclonic during the second half of the animation. The eye of the storm is continually evolving: it appears to form, weaken, and be renewed several times during the lifetime of the storm.

Provided by NOAA/CIRA.

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IR window imagery

Features the cirroform cloud shield, which is rendered in color, the warmest hues indicating the coldest, highest cloud tops. In the second half of the animation, concentric gravity waves can be seen radiating outward from the storm. Because the top of the eyewall cloud slopes outward with increasing height, the eye appears larger than in the MODIS imagery.

Provided by NOAA/CIRA.

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High resolution visible imagery

Reveals further details of the eyewall cloud and the motions of the low clouds within the eye. Visible imagery.

Provided by NOAA/CIRA.

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Hurricane Patricia track

Visible imagery

Around sunrise and sunset, deep convective clouds in the spiral rainbands and gravity waves propagating outward from the center of the storm are rendered visible by the shadows.

Provided by NOAA/CIMSS.

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IR window

From the equivalent blackbody temperature scale at the bottom, it is apparent that the top of the eyewall cloud was colder than -80°C. The storm weakened as it approached the Mexican coast.

Provided by NOAA/CIMSS.

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Typhoon Mawar track

May 19-22, 2023 - IR window imagery

Captures the patch of intense mesoscale convection that preceded cyclogenesis, and the gradual development of a cyclonic circulation.

Provided by CIRA.

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May 22-23, 2023 - IR window imagery

Documents the intensification of Mawar as it tracked west-northwestward toward Guam.

Provided by CIRA.

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May 24, 2023 - IR window imagery

Shows the reintensification of Mawar after it weakened while crossing over Guam.

Provided by CIRA.

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May 22-23, 2023 - Visible imagery

Closeup of the inner structure of Mawar.

Provided by CIRA.

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Eta, November 10, 2020, Cuba

The first clip shows visible imagery, and the second clip shows infrared window imagery in the 10.7μm channel. Gravity waves are clearly evident radiating out from the convective cells. In the third clip, the IR clip is repeated with the lightning superimposed. The color bar the same as in Fig. S.1.1 in the Solutions Manual, except that the gray-shaded areas have a bluish cast.

Provided by NASA/SVS.

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Daniel, Sept. 11, 2023, North Africa

Deep convection that developed in an extratropical cyclone once it drifted over the warm waters of the Mediterranean Sea, transforming it into a tighter, more intense storm, whose rain band provided produced disastrous flooding when it came ashore over Libya. GeoColor imagery.

Provided by CIRA.

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The 2006 season

Column water vapor imagery from the GEOS5 Model, documenting the 2006 tropical cyclone season. The first clip (Sep 1-20, 00:13-00:59) focuses on the Atlantic, sector, the second clip (Sep 1-20, 0:59-1:45) on the Pacific sector, and the third clip (Sep. 1-10, 1:45-2:09) on the Indian Ocean sector.

Provided by NASA/SVS.

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Florida, March 15, 2022 - Visible imagery

Daytime sea breezes advance landward on both Atlantic and Gulf coasts, confining the afternoon convection to the interior of the peninsula. By late afternoon, the convective cells have become larger than when they first developed during the morning. The circulation around Lake Okeechobee exhibits its own distinctive signature.

Provided by CIRA.

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Cuba, March 23, 2020 - Visible imagery

Sea breezes advance landward on both sides of the island; the one on the windward (north) side of the island moving more quickly. During the afternoon, the sea breezes converge along a line just inland from the south coast.

Provided by CIRA.

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The "Big Island” of Hawaii, November 30 2022 - Daytime GeoColor imagery

Best viewed by downloading and advancing manually. Each day in this four day sequence, shallow convection streamed inland on the windward side of the island, blocked and steered by topographic features, A seabreeze also develops on the leeward side. An eruption was in progress on Mauna Loa, near the center of the island.

Provided by CIRA. Best viewed by downloading and advancing manually.

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Great Lakes, July 31, 2023 - Visible imagery

Despite the smoke from the Canadian wildfires, enough radiation reached the Earth’s surface to support shallow convection over land during the afternoon. Sea breezes developed on the downwind sides of the lakes.

Provided by CIMSS.

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Rain rate, Marine Continent, March-May - IMERG (2000-2018)

Convection breaks out along the front of the advancing seabreeze around or just after noon and spreads inland, peaking in the mountains in late afternoon or evening. During the night, the convection over the islands subsides, and thunderstorms break out over some of the the seas just offshore of the islands. Oner the southwest coast of Sumatra, the afternoon land convection propagates westward over the coastal waters in association with a gravity wave.

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Rain rate, Contiguous US, June-August - IMERG (2000-2018)

Of particular interest is the shifting of the convection between land and sea over the southeastern US and adjacent waters, the nocturnal maximum over the US Great Plains, and the late night / early morning maximum over the Gulf stream.

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Rain rate, Equatorial Africa, March-May - IMERG (2000-2018)

Shows nocturnal lightning over Lake Victoria, and afternoon convection over the mountain ranges to the west of it.

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Lightning, Marine Continent - WWLLN

In units of flashes per square km per year. The 500 m surface elevation contour is shown. Resembles the corresponding video for rain rate.

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Lightning, Central America - WWLLN

In units of flashes per square km per year. The 500 m surface elevation contour is shown. The interplay between coastal geometry, orography, and the background, trade wind flow gives rise to complex pattern of diurnal variability that is quite different along the Atlantic and Pacific coastlines.

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Lightning, Global overview - WWLLN

The diurnal cycle can be followed as the sunlit area propagates westward from hour to hour. It is best seen over continental regions and over the tropical rainforests. Higher amplitude regional features associated with orography and coastal geometry are also clearly evident.

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Surface Pressure

Surface pressure (virtually identical to SLP). The solar tide is dominated by the semidiurnal component S2, which exhibits a zonal wavenumber k = 2 structure. S2 is driven mainly by the heating of ozone by ultraviolet solar radiation in the vicinity of the stratopause level. Upon careful inspection of the individual frames, it is evident that continent-ocean geometry also plays a role in shaping the patterns, albeit a minor one.

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Geopotential Heights on the 1, 10, 100, and 1000 hPa surfaces

Geopotential height on the (top to bottom) 1, 10, 100, and 1000 hPa surfaces. The contour interval is the same (5 m) at all levels so that the amplitudes can be directly compared. The structure is mainly equivalent barotropic, with amplitude increasing with height.

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Filtered 500 hPa height

Geopotential height on the 500 hPa surface, contour interval 1 m. The animation shown in the top panel is based on data that have been filtered to eliminate the semidiurnal solar tide S2 by replacing the hourly value for 00. by (21 + 03)/2, for 01 by (22 + 04)/2, for 02 by (23 + 05)/2, etc. The animation shown in the bottom panel is based on unfiltered data. The solar diurnal tide S1 is clearly evident in the top panel. Consistent with the discussion in the text, S1 is strongly influenced by the land-sea geometry. It is much weaker than S2 shown in the bottom panel.

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Gravity waves

The 50 hPa geostrophic component of the wind field is indicated by arrows, and the scalar speed of the residual by the colored shading. The fields are generated twice daily through the 10 day forecast cycle of the ECMWF operational model. The residual field in the modal decomposition is dominated by gravity wave packets originating in the Andes and dispersing eastward.

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Tight vortices, November 8, 2023

As in 21.5-1 but for the lower tropospheric flow in the vicinity of typhoon Khanun. The tight vortex in the residual field near the center of the storm is in cyclostrophic balance. It appears as part of the residual field in the modal decomposition, but it is clearly not an IG wave. The much weaker quasi-stationary anticyclonic vortex in the first half of the sequence is the wake of the island of Taiwan.

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6.7: Spherical harmonics tutorial

For further specifics, see 6.7 in the Supplementary Figures Library. Provided by Cyp - Own work, CC BY-SA 3.0 .

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The Morning Glory cloud, August 14, 15, and 16, 2023

Satellite imagery showing gravity waves over the Gulf of Carpentaria on three successive mornings. This cloud is typically observed several or more times per year during the winter (dry) season. It is apparently triggered, not by deep convection, but by the convergence of seabreezes along the ridge of the narrow Cape York Peninsula along the eastern side of the Gulf the previous afternoon. The waves propagate along an inversion at the top of the boundary layer.

Provided by Andrew Miskelly / Weatherzone.

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Planetary wave response to an off-equatorial heat source

As in the previous video but the heat source is centered at 20 degrees latitude. Provided by Ayumu Miyamoto and Shang-Ping Xie.

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