Weird Clouds Look Even Better From Space

From http://www.wired.com/wiredscience/2010/05/gallery-clouds/all/1













Clouds are fascinating because they take on so many different, beautiful shapes and are constantly changing. Cloud-watching from Earth can be endlessly entertaining, but some of the most amazing cloud patterns can only be properly appreciated from space.

Satellites can take in thousands of miles of the Earth’s surface in one shot, revealing complicated and intriguing cloud patterns we could never see from below. We’ve gathered here some of the best cloud formations to see from above.

Click on any of the images in this gallery for a higher-resolution version.

Von Kármán Vortex Street, Selkirk Island

The crazy-looking swirls in the image above may be one of the weirdest cloud formations that can be seen from space. The pattern is known as a von Kármán vortex street, named after Theodore von Kármán. First noticed in the laboratory by fluid dynamicists, it occurs when a more-viscous fluid flows through water and encounters a cylindrical object, which creates vortices in the flow.

Alejandro Selkirk Island, off the Chilean coast, is acting like the cylinder in the image above, taken by the Landsat 7 satellite in September 1999. A beautiful vortex street disrupts a layer of stratocumulus clouds low enough to be affected by the island, which rises a mile above sea level.

More strange and wonderful vortex streets formed by islands can be seen in the images below and in the last slide of this gallery. Below is Guadalupe Island, 21 miles off the coast of Mexico’s Baja California, shot in 2000 by Landsat 7; Rishiri Island in the northern Sea of Japan, photographed by space shuttle astronauts in 2001; and Wrangel Island, above the Arctic Circle northeast of Siberia, flanked by a vortex street created by the smaller Gerald Island, imaged by NASA’s Aqua satellite in August 2008.

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Images: 1) Bob Cahalan/NASA, USGS. 2) NASA. 3) NASA. 4) NASA (STS100-710-182).













Anvil Cloud, Western Africa

Under specific conditions, the towering, fluffy white clouds known as cumulonimbus can become flattened into the shape of an anvil. The anvil in the image above was captured by astronauts aboard the International Space Station as it crossed over western Africa in February 2008.

Cumulonimbus clouds form when air warmed by sun-heated ground rises. If the warm air contains water vapor and it encounters cooler air, the moisture condenses into water droplets. The air continues to rise, expand and cool as atmospheric pressure and temperature decrease. At the same time, heat released from the phase transition between water vapor and liquid water warms the air. The cooler air wants to fall, while the warmed air wants to rise, which sets up convection cells that feed the tall cloud towers and often result in thunderstorms.

In the tropics, these towers can grow to be 12 miles tall. At this point, they hit the tropopause, which is the boundary between the troposphere and stratosphere layers of the atmosphere. Beyond the tropopause, air no longer cools as it rises, which stops the cloud top, which may then spread and flatten along the boundary.

The image below, taken by an astronaut aboard the space shuttle in February 1984, shows several cumulonimbus towers and anvils over Brazil.

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Images: NASA


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Gravity Waves, Indian Ocean

The gravity-wave clouds in this image look almost like a fingerprint on the stratocumulus cloud layer below them. This intriguing pattern occurs when air below moves vertically to disturb a stable cloud layer, causing a ripple effect.

The disturbance can be caused by features of the terrain below, such as a mountain range, but these waves overlie the Indian Ocean and are more likely the result of a vertical updraft caused by a thunderstorm or some other atmospheric instability.

The best viewpoint for this phenomenon is probably from space. This natural-color image from the multi-angle imaging spectro-radiometer aboard NASA’s Terra satellite was captured in October 2003.

Image: NASA













Wave Clouds, Amsterdam Island

Amsterdam Island is just 13 miles long, but the island’s volcano rises 2,844 feet above the surface of the Indian Ocean, high enough to disturb the clouds above it. In the image above, the island creates a wake of lenticular clouds, sometimes called wave clouds when they form this pattern.

The wave clouds were created by wind that hit the island and was forced upward by the volcano. As the air rises, it cools, and water vapor condenses and forms clouds. The air then falls down the other side of the volcano, and the clouds evaporate. This pattern alternates as air flows past the island, creating what resembles the wake behind a ship.

From the ground, lenticular clouds often look like flying saucers or continuous shelves. The image above was taken by the moderate-resolution imaging spectro-radiometer (MODIS) aboard the Terra satellite in December 2005.

Below, the Sandwich Islands in the Southern Atlantic are also creating wakes as low-lying stratiform clouds pass by their volcanic peaks. The size of the wake corresponds to the height of each peak, which range in elevation from 620 feet to 4,500 feet. This image was captured by the MODIS instrument on NASA’s Aqua satellite in January 2004.

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Images: 1) Jeff Schmaltz/NASA. 2) Jacques Descloitres/NASA.













Cyclones, South Atlantic Ocean

The swirling pattern in the image above is two tangled polar cyclones over the South Atlantic Ocean. Cyclones like these are often created by low-pressure systems over cold, open water. The spot of green in the upper left is water just off the southern tip of Africa.

This image was taken by the MODIS instrument on NASA’s Terra satellite in April  2009.

Image:  Jeff Schmaltz/NASA













Popcorn Clouds, Brazil

This vast, impressively uniform layer of small clouds over the Amazon rain forest shown in the image above is the product of rapid plant growth. During the forest’s dry season, the plants get more sunlight. This leads to more growth and more photosynthesis, which releases water vapor into the air through transpiration. The warm, wet air rises and cools, causing the water vapor to condense into small, fluffy white clouds that resemble popcorn, particularly in the close-up below.

In this image, taken by the MODIS instrument on NASA’s Aqua satellite on August 19, 2009, the cloud cover is broken by the rivers, which don’t give off as much heat as the land does to warm the air and trigger the cloud formation.

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Images: Jeff Schmaltz/NASA













 

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