World Library  
Flag as Inappropriate
Email this Article

Polar easterlies

Article Id: WHEBN0000786562
Reproduction Date:

Title: Polar easterlies  
Author: World Heritage Encyclopedia
Language: English
Subject: Annual cycle, Atmospheric circulation, East wind, Prevailing winds, Westerlies
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Polar easterlies

The polar easterlies (also Polar Hadley cells) are the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high latitudes.[1] Cold air subsides at the poles creating the high pressure, forcing an equatorward outflow of air; that outflow is then deflected westward by the Coriolis effect. Unlike the westerlies in the middle latitudes, the polar easterlies are often weak and irregular. These prevailing winds blow from the polar easterlies are one of the five primary wind zones, known as wind belts, that make up our atmosphere's circulatory system. This particular belt of wind begins at approximately 60 degrees north and south latitude and reaches to the poles. When air moves near the poles, cold temperatures shrink the air. This promotes air from warmer latitudes to flow into the area, causing a polar high-pressure zone. Air from this high-pressure zone then rushes toward the low-pressure zone surrounding the sub-polar region. This flow of air is altered by the Earth's rotation and deflected west, hence the name easterlies (easterly means from the east, not to the east).

The other four primary wind zones are known as the doldrums, trade winds, prevailing westerlies and horse latitudes. The sun heats the Earth in an uneven fashion, causing variations in pressure in the atmosphere. As air moves between high- and low-pressure zones, its path is deflected—as we saw with the polar easterlies—thanks to the rotation of the Earth. All of this unequal heat, rushing air and spinning Earth combine to form global currents such as the polar easterlies.

Another example of the phenomenon would be the trade winds, which reach from where the doldrums (the area that gets the biggest blast of heat from the sun) leave off at about 5 degrees north and south latitude to as far as 30 degrees north and south. They are caused by air moving into the area from the subtropics to fill the void left by the doldrums' rising air. The trade winds blow steadily westward out of the northeast in the Northern Hemisphere and out of the southeast in the Southern Hemisphere. Sailors in earlier times, traveling by wind current and sail only, counted upon the reliability of the trade winds to help them along on their voyages. Similarly, they sought to avoid the doldrums, where the wind was so scant they risked coming to a complete stop.

References

  1. ^ Glossary of Meteorology (2009).They are called Easterlies because the blow from the east .p=1&query=polar+easterlies&submit=Search Polar easterlies. American Meteorological Society. Retrieved on 2009-04-15.

See also

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.