Question

Identify the planetary winds blowing between the following pressure belts.
a) Between the polar highs and subpolar lows
b) Between the subtropical highs and Equatorial low
c) Between the subtropical high and sub polar lows.

Answer 1

Hint: Wind, in simple terms, can be defined as air in motion. Around our earth, atmospheric pressure is not even. This is why air moves from areas of high pressure to low pressure causing winds.

Complete answer:
> Pressure belts are distinct identifiable zones of homogenous pressure on earth. Equatorial low, subtropical highs, sub polar lows and polar highs are the types of pressure belt on earth. Planetary winds are the winds in the lower atmosphere that are being controlled by these pressure belts.
a) Between polar high and subpolar lows, the polar easterlies blow. These are cold, dry winds that blow from the high pressure area of the North and South pole to lower pressure subpolar areas. Polar easterlies are weak and irregular and blow east to west. This is because these winds that flow towards the equator from the poles are deflected by coriolis force.
b) Between subtropical highs and equatorial lows, the trade winds blow. They cover the area between 5degree to 30 degree north and south. Due to coriolis force , they blow northeast in the northern hemisphere and southeast in the southern hemisphere.
c) Between subtropical highs and subpolar lows are called the westerlies. The westerlies blow between 35 degree to 60 degree in both the hemispheres. As they travel towards the poles from subtropical high pressure belts, coriolis force deflects them and hence the northern hemisphere has south westerlies and southern hemisphere has north westerlies.

Note: Southern hemisphere has stronger and more consistent westerlies than the northern hemisphere. In fact southern hemisphere westerlies are called roaring fifties, screaming sixties and furious fifties. The subtropical high pressure belt( 30degree to 35 degree ) is also called horse latitude. Equatorial low pressure belt is also called doldrums.