Cloud Shadow

On November 20, 2012, the Advanced Land Imager (ALI) on the Earth Observing-1 (EO-1) satellite acquired this image of a layer of clouds casting a distinctive shadow on another cloud deck below. The upper deck was more than 1 kilometer (0.6 miles) above the ground; the lower was less than 1 kilometer up. Both layers were comprised of stratus clouds, a low-lying type that tends to be uniform and flat. When ALI acquired the image, the clouds were above northeastern Germany, near Harz National Park.
While local meteorological conditions affect cloud height, the latitude at which clouds form is also important. Almost all clouds exist in the lowest area of the atmosphere, the troposphere. However, the depth of the troposphere varies depending on the latitude. The troposphere is thinner near the poles than the equator, so clouds can occur at higher levels in the tropics than they do at high- and mid-latitudes.
ALI provides some of the highest resolution imagery currently collected by NASA’s fleet of Earth-observing satellites. At full resolution, each pixel of an ALI scene corresponds to 10 meters (33 feet) of the Earth’s surface. For comparison, the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua and Terra acquires imagery in which each pixel corresponds to 250 meters (820 feet) of Earth’s surface. The company GISAT maintains lists of high-resolution and low-resolution Earth-observing satellite sensors.

• References

• S'Cool (n.d.) On-line Cloud Chart. Accessed Dec. 21, 2012.

1. Further Reading

2. Earth Observatory (n.d.) Clouds & Radiation.
3. Earth Observatory (2005, Aug. 9) Cloudy with a Change of Drizzle.
4. Earth Observatory (2010, Aug. 31) Finding a Fire Cloud from Space.

NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using Advanced Land Imager data from the NASA EO-1 team. Caption by Adam Voiland, with information from Patrick Minnis and Lin Chambers.

Instrument: 

EO-1 - ALI - NASA

Cloud Streets over the Hudson Bay

On November 13, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this view of cloud streets amidst northwesterly winds over Hudson Bay.
Cloud streets—long parallel bands of cumulus clouds—form when cold air blows over warmer waters, while a warmer air layer (or temperature inversion) rests over the top of both. The comparatively warm water gives up heat and moisture to the cold air above, and columns of heated air called thermals naturally rise through the atmosphere.
The temperature inversion acts like a lid. When the rising thermals hit it, they roll over and loop back on themselves, creating parallel cylinders of rotating air. As this happens, the moisture in the warm air cools and condenses into flat-bottomed, fluffy-topped cumulus clouds that line up parallel to the prevailing wind.
Cloud streets can stretch for hundreds of kilometers if the land or water surface underneath is uniform. Sea surface temperature need to be at least 21°C to 22°C degrees (39°F to 41°F) warmer than the air for cloud streets to form.

• References

• KNMI (n.d) Cloud Streets: Meteorological Physical Background. Accessed November 19, 2012.
• Weather Underground. (2005, April 24). Cloud Streets. Accessed November 19, 2012.
• Earth Observatory. (2011, January 24). Winter Cloud Streets, North Atlantic.

NASA image by Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Adam Voiland.

Instrument: 

Terra - MODIS - NASA

Photos - Weather Observation: South Africa (15 November 2012 )

Communikay @CommunikaySA - Amazing cloud formation looking NE from Kyalami.

Craig Powell ‏@CraigPowell8 - 1hr ago you could see the tops of the storms E of PTA. Image courtesy of a friend.

Pat Ladell - PE 07:20 VERY misty today!

Derron Greyling - Wahooo! We have a some blue skies and a breeze. Don't wanna hear about KZN's 30 percent of rain until my washing is dry.

Francis Proudfoot - Stormclouds coming over Cathkin and Champagne from Lesotho.

Dee de Souza - Been low cloud all day here in Assagay. Feels like it is threatening to drizzle all the time. Temp a chilly 23C

Pieta Myburg - Bloemfontein @16:20

Francis Proudfoot - Beautiful sun shining through clouds on the Ladysmith Estcourt Road.

Ben Engelbrecht - Dundee: Weather Satellite Image: NOAA19

Picture of the Day

Mammatus Clouds Over Saskatchewan
Image Credit & Licence: Craig Lindsay, Wikipedia Explanation: Normal cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm. Resulting mammatus clouds can appear especially dramatic if sunlit from the side. These mammatus clouds were photographed over Regina, Saskatchewan, Canada during the past summer.

Fire in the Sky - Lenticular cloud: Cape Town (21 October 201219h00 SAST)

It was rather grey in Cape Town during today (Sun 21th), but starting clearing
in the late afternoon. The lenticular clouds that were present this morning
were lit up by a spectacular sunset, as captured by the Milneton webcam at
19h00. By 19h10 it was all gone. - Gordon Richardson

Lenticular Cloud observed in Cape Town (20 October 2012)

Lenticular East: Overlooking the Cape Flats from Ou Kaapseweg, looking east

Lenticular West: from Constantia Area, looking West

I tool these photos yesterday (Sending you full resolution) - Jakes ZS1TP

Sunset this evening west of Johannesburg (21 October 2012)

And then nature paints a sunset over the west of Johannesburg. - Image: @Edzardt

SAWDOS: The above clouds are called Mammatus clouds.

Cloud Observation: Lenticular cloud observed near Blouberg, Cape Town (20 October 2012)

Images: Cape Town Webcams (Click on images for larger view.)

The above Lenticular cloud was observed by Richard Koker near Blouberg, Cape Town.

Lenticular clouds (Altocumulus lenticularis) are stationary lens-shaped clouds that form at high altitudes, normally aligned perpendicular to the wind direction. Lenticular clouds can be separated into altocumulus standing lenticularis (ACSL), stratocumulus standing lenticular (SCSL), and cirrocumulus standing lenticular (CCSL). Due to their shape, they have been offered as an explanation for some Unidentified Flying Object (UFO) sightings.

Where stable moist air flows over a mountain or a range of mountains, a series of large-scale standing waves may form on the downwind side. If the temperature at the crest of the wave drops to the dew point, moisture in the air may condense to form lenticular clouds. As the moist air moves back down into the trough of the wave, the cloud may evaporate back into vapor. Under certain conditions, long strings of lenticular clouds can form near the crest of each successive wave, creating a formation known as a "wave cloud." The wave systems cause large vertical air movements and so enough water vapor may condense to produce precipitation. The clouds have been mistaken for UFOs (or "visual cover" for UFOs) because these clouds have a characteristic lens appearance and smooth saucer-like shape. Bright colors (called irisation) are sometimes seen along the edge of lenticular clouds. These clouds have also been known to form in cases where a mountain does not exist, but rather as the result of shear winds created by a front.

Pilots of powered aircraft tend to avoid flying near lenticular clouds because of the turbulence of the rotor systems that accompany them, but glider pilots actively seek them out. The precise location of the rising air mass is fairly easy to predict from the orientation of the clouds. "Wave lift" of this kind is often very smooth and strong, and enables gliders to soar to remarkable altitudes and great distances. The current gliding world records for both distance (over 3,000 km; 1,864 mi) and altitude (15,460 m; 50,721 ft) were set using such lift.

- Wikipedia

Crazy Clouds?

Mammatus clouds over Saskatchewan. Photo: Robinlawless

There are way more types of clouds in the world than “big, white, and puffy,” despite what the drawings of nearly every five year old or, let’s face it, adult would suggest. Varying with altitude, moisture content and how the atmosphere is moving around, clouds come in a vast array of unusual shapes and sizes. Some take on undulating forms, like gravity wave clouds, which arise when a stream of wind undulates up and down as it flows through the air, with clouds forming at the peaks of the wave and clearings at the troughs. And that’s just the beginning. When unusual clouds arise, people tend to get pretty excited.

- Smithsonian.com

Images: Sunset over Port Elizabeth

Image: PE Stadium  - Ryna Bakkes

Taken at Amsterdamhoek. - Nick Cadle

Sunset today 17:45 Schoemanmakerskop - Diana Kitshoff

Evolving Views of Clouds

(Click on images for larger view.)

Although people have observed clouds for tens of thousands of years, one group of clouds long escaped human detection. Not because those clouds were too small to see, but because they were too big. The dawn of the satellite era changed that, revealing a type of cloud that scientists named “actinoform.” The name of these radial, or leaf-shaped, clouds is based on the Greek term for “ray.”
The first recorded detection of an actinoform cloud occurred on August 16, 1962, southwest of Hawaii. NASA’s Television Infrared Observation Satellite V (TIROS V) observed a chain of the clouds west of Peru on October 7, 1962 (second image above). This was was the first picture featured in the “Picture of the Month” series in Monthly Weather Review. The caption read: “It is appropriate that this series begins with a type of cloud pattern discovered on TIROS pictures. The numbered arrows indicate a line of actinoform patterns presumably in various stages of development. Numbers 4 and 5 almost merge and 1 is poorly organized, but the typical pattern is easily seen in 2 and 3.”
Over the past five decades, accumulating satellite observations have shown that actinoform clouds are more common and more complex than originally thought. They occur practically everywhere that marine stratus or stratocumulus clouds form. As indicated in the TIROS image, these cloud fields can link together, forming chains several times as long as any individual actinoform cloud.
The last 50 years have not only seen plentiful observations of actinoform clouds, but also improvements in satellite technology. The top image above was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on June 28, 2012. The image shows multiple cloud types: open- and closed-cell and actinoform clouds.
NASA-sponsored research has linked the clouds to recurring weather patterns in Southern California. While actinoform clouds look appealing from the perspective of a satellite sensor, on the ground they have proven less charming. Depending on the season, actinoform clouds can blow ashore, bringing gloomy, drizzly weather with them. In California, these cloud fields are associated with weather patterns nicknamed May Gray and June Gloom.
Beyond their role in weather, clouds play an important role in regulating Earth’s temperature—reflecting solar radiation back into space during the day, and trapping heat at night. For the last 50 years, the satellite sensors have observed these complicated, frequently occurring actinoform clouds, providing an enhanced understanding of weather, along with pretty pictures.

1. References

2. Garay, M.J., Davies, R., Averill, C., Westphal, J.A. (2004) Actinoform clouds: Overlooked examples of cloud self-organization at the mesoscale. Bulletin of the American Meteorological Society, 85, 1585–1594.
3. Haag, A.L. (2005, August 9) Cloudy with a chance of drizzle. NASA Earth Observatory.
4. NASA Science. (2012, June 5) TIROS.
5. U.S. Navy Weather Research Facility. (1967, June) Photographs from Meteorological Satellites. (PDF file). A collection of the picture of the month series from Monthly Weather Review, January 1963 to May 1967.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team, Goddard Space Flight Center. TIROS V image courtesy NOAA Central Library. Caption by Michon Scott.

Instrument: 

Terra - MODIS - NASA

A Glorious View

A layer of stratocumulus clouds over the Pacific Ocean served as the backdrop for this rainbow-like optical phenomenon known as a glory. Glories generally appear as concentric rings of color in front of mist or fog. They form when water droplets within clouds scatter sunlight back toward a source of illumination (in this case the Sun). The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired the image on June 20, 2012.
Although glories may look similar to rainbows, the way light is scattered to produce them is different. Rainbows are formed by refraction and reflection; glories are formed by backward diffraction. The most vivid glories form when an observer looks down on thin clouds with droplets that are between 10 and 30 microns in diameter. The brightest and most colorful glories also form when droplets are roughly the same size.
From the ground or an airplane, glories appear as circular rings of color. The space shuttle Columbia observed a circular glory from space in 2003. In the image above, however, the glory does not appear circular. That’s because MODIS scans the Earth’s surface in swaths perpendicular to the path followed by the satellite. And since the swaths show horizontal cross sections through the rings of the glory, the glory here appears as two elongated bands of color that run parallel to the path of the satellite, rather than a full circle.
Glories always appear around the spot directly opposite the Sun, from the perspective of the viewer. This spot is called the anti-solar point. To visualize this, imagine a line connecting the Sun, a viewer, and the spot where the glory appears. In this case, the anti-solar point falls about halfway between the two colored lines of the glory.
Glories are usually seen against a background of white clouds. Clouds are white because the sunlight is scattered many times by multiple droplets within the clouds. The white light often obscures details of glories, but without them in the background, the glory would not be visible.
Another notable feature in this image are the swirling von karman vortices that are visible to the right of the glory. The alternating double row of vortices form in the wake of an obstacle, in this instance the eastern Pacific island of Guadalupe.

• References

• Atmospheric Optics. (n.d.) The Glory. Accessed June 26, 2012.
• Gedzelman, S. (2003, January 20). Simulating Glories and Cloudbows in Color. Applied Optics.
• Floor, K. (2012). Glory from Space. Accessed June 26, 2012.
• Israelevich. P..L. (2009, December). First Observations of Glory from Space. Bulletin of the American Meteorological Society.
• Laven, P. (2005). How are Glories Formed? Applied Optics.
• Laven, P. (n.d.) Glories and Brocken Spectre. Accessed June 26, 2012.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Adam Voiland.

Instrument: 

Terra - MODIS - NASA

"Lenticular wave clouds" over Table Mountain (Wednesday 2nd May 2012)

Image: Cape Town Web-Cam (Click on image for larger view.) Image provided by Ben Engelbrecht, Dundee.

SAWDOS - Lenticular clouds (Altocumulus lenticularis) are stationary lens-shaped clouds that form at high altitudes, normally aligned perpendicular to the wind direction. Lenticular clouds can be separated into altocumulus standing lenticularis (ACSL), stratocumulus standing lenticular (SCSL), and cirrocumulus standing lenticular (CCSL). Due to their shape, they are often mistaken for Unidentified Flying Objects (UFOs). It would appear that there was some formation of a lenticular cloud over table mountain at 14h00 today. Ironically in 2011 also on the 2 May a lenticular wave cloud was observed on table mountain. Here is the link:  http://saweatherobserver.blogspot.com/2011/05/lenticular-wave-clouds-over-table.html

Altocumulus undulatus cloud spotted over Mossel Bay ( 25 April 2012 - 12h33 SAST)

Images: SAWS (Click on images for larger view.)

Wave Clouds Near Île aux Cochons, Southern Indian Ocean

(Click on image for larger view.)

This astronaut photograph illustrates the formation of wave clouds in the wake, or downwind side, of Île aux Cochons (“Pig Island”) in the southern Indian Ocean. The island is located approximately 3,000 kilometers (1,900 miles) southeast of South Africa and 2,300 kilometers (1,400 miles) northwest of Antarctica. In this view from the International Space Station, only a part of the eastern coastline is visible.

The island is volcanic in origin and has a summit elevation of 775 meters (2,543 feet) above sea level. The Île aux Cochons stratovolcano is thought to have erupted within the past 12,000 years; however, no historical activity has been recorded.

The summit elevation is high enough for the land surface to interact with cloud layers and with winds flowing past the island. In this image, two cloud layers are visible. The lower, more uniform layer consists of roughly parallel “cloud streets” that suggest the winds blowing out of the west. When air masses run into the summit of Île aux Cochons, moisture-laden air rises and cools, causing water vapor to condense into clouds.

Once the air masses pass over the summit, they descend and may encounter alternating moist and dry air layers, enabling the formation of the discontinuous, chevron-shaped wave clouds. While their appearance suggests that the clouds are forming in the wake of the island and moving eastwards, it is in fact the air mass that is moving, with clouds forming in regions of moist air and dissipating in dry regions.

Île aux Cochons is the westernmost of the islands in the sub-antarctic Crozet Archipelago, part of the French Southern and Antarctic Lands. Except for occasional research visits, the island is uninhabited. The island is an important breeding site for seabirds, including the world’s largest King Penguin colony.

Astronaut photograph ISS030-E-193144 was acquired on March 25, 2012, with a Nikon D2Xs digital camera using a 180 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 30 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/ESCG at NASA-JSC.

Instrument:
ISS - Digital Camera - NASA

Wave Clouds Near Île aux Cochons, Southern Indian Ocean

(Click on image for larger view.)

This astronaut photograph illustrates the formation of wave clouds in the wake, or downwind side, of Île aux Cochons (“Pig Island”) in the southern Indian Ocean. The island is located approximately 3,000 kilometers (1,900 miles) southeast of South Africa and 2,300 kilometers (1,400 miles) northwest of Antarctica. In this view from the International Space Station, only a part of the eastern coastline is visible (image center).

The island is volcanic in origin and has a summit elevation of 775 meters (2,543 feet) above sea level. The Île aux Cochons stratovolcano is thought to have erupted within the past 12,000 years; however, no historical activity has been recorded.

The summit elevation is high enough for the land surface to interact with cloud layers and winds flowing past the island, and two major cloud layers are visible. The lower, more uniform layer consists of roughly parallel cloud “streets” that suggest a westerly flow pattern of air. When the air mass encounters the Île aux Cochons, moisture-laden air rises and cools, causing more water vapor to condense into clouds.
As the air mass passes over the summit and descends, it may encounter alternating moist and dry air layers, enabling the formation of the discontinuous, chevron-shaped wave clouds. While their appearance suggests that the clouds are forming in the wake of the island and moving eastwards, it is in fact the air mass that is moving, with clouds forming in regions of moist air and dissipating in dry regions.

Île aux Cochons is the westernmost of the islands in the sub-antarctic Crozet Archipelago, part of the French Southern and Antarctic Lands. Except for occasional research visits, the island is uninhabited. The island is an important breeding site for seabirds, including the world’s largest King Penguin colony.

Astronaut photograph ISS030-E-193144 was acquired on March 25, 2012, with a Nikon D2Xs digital camera using a 180 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 30 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/ESCG at NASA-JSC.

Instrument:
ISS - Digital Camera - NASA

Von Kármán Vortices in the Greenland Sea

(Click on image for large view.)

Theodore von Kármán, a Hungarian-American physicist, is well-known within NASA for helping found the Jet Propulsion Laboratory, but in atmospheric science circles he is most celebrated for his research on fluid turbulence and his pioneering work on a phenomenon known today as von Kármán vortices.

Von Kármán vortices, which can appear as long linear chains of spiral eddies, form nearly anywhere that fluid flow is disturbed by an object. The atmosphere behaves like a fluid, so the wing of an airplane, a bridge, and even an island can cause the vortices to form.

In the image above, an isolated Norwegian territory in the North Atlantic Ocean, called Jan Mayen Island, is responsible for the spiraling cloud pattern. The unique flow occurs when winds rushing from the north encounter Beerenberg Volcano, a snow-covered peak on the eastern end of the island that rises 2.2 kilometers (1.4 miles) above the sea surface. As winds pass around the volcano, the disturbance in the flow propagates downstream in the form of a double row of vortices that alternate their direction of rotation.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite captured the image on April 4, 2012.

References:
GES DISC. Science Focus: Von Karman Vortices. Accessed April 16, 2012.
Earth Observatory. (2002) A Vortex Street in the Arctic.
Volcano World. Beerenberg. Accessed April 16, 2002.
JPL History. Theodore von Kármán. Accessed April 16, 2012.
NASA image by Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response. Caption by Adam Voiland.

Instrument:
Aqua - MODIS - NASA

Cloud streets around southern Greenland

Image: Rapid Responce-Terra Aqua-NASA (Click on image for larger view.)

Cloud Streets Behind Cape Verde Islands

(Click on image for larger view.)

The roughly symmetrical patterns of swirls and curves in the clouds in this image are cloud vortex streets, also known as von Karman vortices. They were created by low-level winds rushing over the Cape Verde Islands off the coast of northwestern Africa.
Von Karman vortices form nearly everywhere that fluid flow is disturbed by an object. In this image, the “object” that is disturbing the fluid flow is the group of Cape Verde islands. As a prevailing wind encounters the island, the disturbance in the flow propagates downstream of the island in the form of a double row of vortices which alternate their direction of rotation.

- Earth Snapshot

More about chemtrails

Image: A photo of a "chemtrail" (on the left) as supplied by Mr TS Thomas who says that the "chemtrails" disperse into a cloud-like shape. These "clouds" contains a powdery substance that falls to the ground. It is not the same as a ‘contrail’ (on the right), the vapour trail behind a jet, he says.

GEORGE NEWS - A little research on the Internet revealed that reports of "chemtrails" apparently started emerging in the late 90s in the US, where chemtrail believers accuse the government of spreading harmful chemicals through such methods.

According to chemtrailcentral.com, a website dedicated to the topic, the Wall Street Journal and Washington Post have reported in the past that civilians may have died as a result of exposure to live agents sprayed by the Army and Navy during biological warfare tests.

Some European countries are allegedly also subjected to such campaigns. And the forces behind these campaigns are believed to be governments and "the militaries of the world".

Chemtrailcentral.com quotes from a research project on chemtrail formation over Houston, Texas done during 2000. It was found that "highly persistent trails lasting for many hours" were seen above Houston on the majority of days during the data collection period.

"Additionally it was discovered that the jets that were responsible for leaving highly persistent trails that last for hours did not ever appear on Flight Explorer." (Flight Explorer is an Internet-based flight-tracking tool that allows the user to obtain information about commercial, passenger, and private flights.

Military flights are filtered from the data stream.) The flights not identified on Flight Explorer during the research period, were observed to produce trails "with persistence from 20 seconds to several hours". These would be the alleged "chemtrails".

The aim of chemtrail spraying
There are three alleged reasons for spraying chemicals over cities, according to chemtrailcentral.com: weather manipulation, depopulation (killing people) and inoculation of the population.

Detox
On the Internet you will even find tips on how to detox from the chemicals and heavy metals resulting from chemtrails. It is up to the reader to decide whether you need such a detox if you are a resident of George.

ARTICLE: ALIDA DE BEER, GEORGE HERALD JOURNALIST

- George Herald