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Why Are Deserts Dry?
The deserts of the world today are not the deserts of the planet's past. Fossilized hippopotamus and elephant bones tell us that the Sahara, for instance, was a much moister and more hospitable environment 8,000 years ago than it is now. Each of the Earth's modern deserts are a consequence of one of the following mechanisms: air mass subsidence, rain shadows, distant moisture sources, or cold offshore temperatures at the sea's surface. This site uses text and scientific illustrations to describe how each of these mechanisms results in the occurrence of deserts.
Intended for grade levels:
  • High (9-12)
Type of resource:
  • Visual:
    • Illustration - scientific
  • Text:
    • Ref. material
  • Atmospheric science
  • Climatology
Technical requirements:
No specific technical requirements, just a browser required
Cost / Copyright:
No cost
NASA materials may not be used to state or imply the endorsement by NASA or by any NASA employee of a commercial product, service or activity, or used in any other manner that might mislead. NASA should be acknowledged as the source of its material. It is unlawful to falsely claim copyright or other rights in NASA material. NASA shall in no way be liable for any costs, expenses, claims or demands arising out of use of NASA's cassettes and photographs by a recipient or a recipient's distributees. NASA personnel are not authorized to sign indemnity or hold harmless statements, releases from copyright infringement, or documents granting exclusive use rights.
DLESE Catalog ID: NASA-Edmall-2523
Resource contact / Creator / Publisher:
Contributor: Len Milich
Arid Lands Resource Sciences