Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Rain Distribution
Name: Ehab
Status: other
Grade: other
Location: N/A
Country: N/A
Date: 8/17/2005


Question:
Why, in some parts of Earth, rain falls in huge amounts while in other parts of Earth rain does not fall at all?


Replies:
Dear Ehab-

Rain is influenced by wind currents and topography. When moist winds strike mountain ranges, the air is forced to ascend, and the moisture falls out of the clouds as rain or snow. In some areas, the winds contain very little moisture, and no precipitation can fall. Areas receiving less than 10 inches of rain in a year are classified as deserts.

Factors other than topography cause rain also...such as fronts, which cause moist air to ascend. But when there is little or no moisture in the air, for whatever reason, precipitation is unlikely.

Wendell Bechtold, meteorologist
Forecaster, National Weather Service
Weather Forecast Office, St. Louis, MO.


Ehab,

The weather, whatever the parameter such as temperature, humidity, rainfall, etc. is mostly dependent on climate and climate is greatly dependent on the geography and topography of the area.

Rainfall is heavier in areas where there is abundant atmospheric moisture, such as in the tropics, near an ocean coastline, near an area of an ocean where there are seasonal monsoon rains (southeast Asia for instance), etc.

Little rainfall occurs where there is little available moisture because an area is located far from an ocean (Sahara desert for instance), or is in the lee of mountains (moisture "rains" out on the leading side of the mountains, leaving the air "dry"), or is too cold (Arctic regions are cold deserts).

David R. Cook
Atmospheric Physics and Chemistry Section
Environmental Assessment Division
Argonne National Laboratory


Click here to return to the Weather Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory