Skip to main content
Clouds

Above and Beyond: Valley Fog in British Columbia

How does valley fog form?

Credits

All programs produced by: Space Telescope Science Institute, Office of Public Outreach
 
All images, illustrations, and videos courtesy of NASA
 
except:
 
·       Cloud illustrations by Marc Lussier, STScI
·       Sea creature illustration copyright The National Library of Israel, Shapell Family Digitization Project and The Hebrew University of Jerusalem, _Department of Geography – Historic Cities Research Project
·       Various cloud photos courtesy of Marc Lussier
·       Valley fog photo courtesy of Lucy Albert
·       Clouds time-lapse video courtesy of Ethan Alexander Cook
·       Photo of cumulus clouds over field courtesy of PiccoloNamek, Wikipedia
·       Towering cumulus cloud photo courtesy of Jim W. Lee
·       Noctilucent cloud photo copyright Jan Erik Paulsen 
·       Noctilucent cloud photo courtesy of P-M Hedén, www.clearskies.se, www.twanight.org
 
Music courtesy of Associated Production Music
 
Written by Andrea Gianopoulos
Designed by Marc Lussier

Transcript

(SPEECH)
[MUSIC PLAYING]
 
(DESCRIPTION)
Thick clouds cover a valley.
 
Text, Valley Fog, British Columbia.
 
Low-lying, layered, stratus clouds that form at ground level are called fog.
 
Moving down the foggy mountains into the valley.
 
Text, In the Pacific Northwest, valley fog forms when cold air sinks into a valley.
 
Looking down on land edged with green and branched white in the center.
 
Text, Moist air in the valley gets chilled and water vapor condenses into fog droplets.
 
A thick patch of white is labeled "fog."
 
Text, When fog becomes thick enough, it reflects a large amount of sunlight back into space.
 
Water tributaries branch into the land.
 
Text, These low-lying stratus clouds also allow some of Earth's heat to escape to space.
 
Text, This cools the surface.