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Where on Earth: Spiraling Clouds off the West Coast of Africa

What causes the clouds in this image to appear in spiral patterns? 

Credits

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory: https://earthobservatory.nasa.gov/  

  • NASA Earth Observatory image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview: https://earthobservatory.nasa.gov/images/146971/cloudy-curls 

  • Image of the Day story by Kasha Patel Google Earth imagery from Landsat/Copernicus, SIO, NOAA, U.S. Navy, NGA, GEBCO, U.S. Department of State Geographer, Google, Basarsoft, GeoBasis-DE/BKG 

  • Adaptation to ViewSpace by Claire Blome, Margaret W. Carruthers, and Dani Player 

  • Music from Music for Nonprofits

Transcript

(SPEECH)
[GENTLE MUSIC]
 
(DESCRIPTION)
Collage of distinct satellite images of natural phenomena.
 
Text, where on earth?
 
Satellite image, a layer of clouds over the ocean with a spiral that snakes down the center.
 
Text, what causes the swirling patterns in these clouds? A, ships, B, an island, C, a dolphin pod, D, a volcanic eruption.
 
B is highlighted, an island.
 
Spiraling clouds off the West coast of Africa. Madeira Island labeled. Text, when clouds driven by wind encounter a landform, they flow around it. As they move past this island, the clouds form chains of patterns known as spiral eddies.
 
The pattern of the spirals depends on the intensity of the wind.
 
These spiral eddies are known as von Karman vortices.
 
They are a familiar atmosphere phenomenon, especially in areas where trade winds are prevalent.
 
Satellites help us see these distinctive patterns from above.
 
The map recedes until we have the whole Earth before us.
 
Text, where on earth?