At a Glance: Desert Types

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This video explains where there are deserts, and why they formed there.

Credits


Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory.

All images, illustrations, and videos courtesy of NASA
 
except:
·       Image of Antarctic snow dunes courtesy of Mark Fahnestock, University of Maryland, College Park
·       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
·       Image of clouds off Namibian coast courtesy of Chelys
·       Image of dunes in the Namib Desert courtesy of the USGS EROS Data Center Satellite Systems Branch
·       Namibian dune photo courtesy of Wikimedia user Alcazarfr
·       Photo of the Mandara Oasis in Libya courtesy of Rudolph Baumann
·       Photo of Astrophytum ornatum cactus courtesy of Wikimedia user Stan Shebs
·       Photos of desert plants courtesy of Wikimedia user Halfalah and Dr. Eric Christian (NASA)
·       Photo of fishhook barrel cactus courtesy of Susan Lynn Peterson
·       Photo of Ubari Oasis in Libya courtesy of Wikimedia user Sfivat
·       Image of alluvial fan in Takla Makan Desert courtesy of the USGS EROS Data Center Satellite Systems Branch
·       Photos of salt-covered croplands courtesy of the USDA Natural Resources Conservation Service
 
Music courtesy of Associated Production Music
Written by Andrea Gianopoulos
Designed by Marc Lussier

Transcript


(SPEECH)
[MUSIC PLAYING]
 
(DESCRIPTION)
Text, at-a-GLANCE. Where Are The Deserts?
 
Deserts exist in various places: along coastlines, in polar regions, near the center of continents, and even in tropical regions.
 
On a map, pins drop on rain-shadow desert in the Western United States, trade-wind desert in Northern Africa, and coastal desert on the southwest coast of Africa.
 
Text, when tall mountain ranges sap moisture-rich ocean winds of their precipitation, rain-shadow deserts form.
 
The map zooms in to the rain-shadow desert in the Western United States.
 
Text, as moisture-rich winds from the Pacific Ocean rise along the Sierra Nevada mountain range, they cool and form clouds that drop rain and snow on the upwind side of the mountains.
 
Arrows move from the Pacific Ocean towards the mountains in California.
 
When they descend on the downwind (or leeward) side of the range, the winds are warm and dry.
 
Arrows move from the mountains towards Nevada.
 
These warm, dry winds create a rain-shadow desert over large sections of Nevada, Utah, Arizona, and Colorado.
 
The map zooms back out. Two lines appear across the map at 30 degrees north and 30 degrees south.
 
Text, trade-wind deserts form as dry air sinks along the Horse Latitudes, roughly 30 degrees north and south of the equator.
 
This descending air breaks up clouds, allowing more sunlight to heat the land below.
 
A line appears at the equator. Arrows move in towards the equator from the Horse Latitudes.
 
Text, the air flows back toward the equator along Earth's surface, forming the trade winds.
 
The map zooms in to the trade-wind desert on the North African coast.
 
Text, the great deserts of North Africa are trade-wind deserts.
 
The map zooms back out. Text, coastal deserts are most often found on the western edges of continents.
 
The map zooms in to the coastal desert on the Namibian Coast, Southern Africa. Text, the vast Namib Desert hugs the coastline of Namibia along the western coast of Africa.
 
An arrow moves up along the coast. Text, Benguela Current
 
A cold Atlantic Ocean current that parallels the coast suppresses rainfall.
 
Arrows move towards the coast from Namibia. Text, when the cold, moist Atlantic air meets the hot, dry desert winds, it forms fog that blankets the Namib Desert coastline and can stretch some 30 to 40 miles inland.
 
This meager but reliable source of moisture helps sustain the Namib Desert's limited number of plants and animals.