Easterlies And Westerlies

Between the equator and about 30°N, the air at the surface flows generally toward the equator, from a zone of relatively high pressure to a zone of relatively low pressure. The same thing happens between the equator and about 30°S. As the air reaches progressively lower latitudes (that is, it gets closer to the equator), the tangential speed of the earth's surface, resulting from the rotation of the planet, increases. Therefore, air flowing toward the equator is deflected toward the west; the earth literally speeds up beneath it. We find prevailing easterly winds in these regions, known as the torrid zones or the tropics, for this reason.

Between 30°N and 60°N, and also between 30°S and 60°S, the air at the surface tends to flow away from the equator and toward the pole, from the semipermanent 30° high-pressure zone toward the semipermanent 60° low-pressure zone. As the air near the surface moves poleward, the earth slows down underneath it. Thus, the air is deflected in the same direction the planet rotates. For this reason, we find prevailing westerly surface winds in the mid-latitude regions, which are called the temperate zones.

Between 60°N and the north pole, and also between 60°S and the south pole, the air flow is generally away from the poles and toward the equator. The effect here is the same as it is in the tropics, but of course at much colder temperatures. The earth speeds up under the air near the surface as it flows away from the pole. There are prevailing easterly surface winds in the arctic and antarctic regions, which are called the frigid zones.

The prevailing winds of the torrid, temperate, and frigid zones sometimes shift because of changes in the locations of the semipermanent high and low pressure belts. In general, however, the torrid zones have easterly winds called the trade winds, the temperate zones have westerly winds called the prevailing westerlies, and the frigid zones have easterly winds called the polar easterlies. The earth's atmosphere is thus broken up into six major belts or zones that girdle the planet.

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Responses

  • MACI
    Why is westerlies called westerlies and not easterlies?
    7 years ago
  • brady
    What is closer to the equator westerlies and easterlies?
    6 years ago
  • travis
    Are easterlies and tradewinds the same thing?
    3 years ago
  • Brenda Garden
    What happens when the westerlies combine with the polar easterlies?
    2 years ago
  • viola
    Why there is air movement in tropical easterlies?
    2 years ago
  • felix
    Why surface winds are generally northeasterlies?
    2 years ago
  • letitia
    What is the area of low pressure between polar easterlies and westerlies?
    2 years ago
  • eemil
    What is westerlies in metorology?
    2 years ago
  • CINDY
    What are trade winds and westerlies?
    2 years ago
  • myrtle
    What happens to the westerlies if rotation of Earth reversed?
    1 year ago

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