There are three main permanent winds— Trade Winds, Westerlies, and Polar Easterlies.
Trade Winds
- The trade winds blow in the tropics between the subtropical high-pressure belt and the equatorial low-pressure belt between 30°N and 30°S.
- Trade winds are warm winds, and hence, they pick up moisture and bring heavy rainfall on the eastern sides of the tropical islands.
- They are deflected to the right of their course in the Northern Hemisphere and to the south in the Southern Hemisphere. Thus, in the Northern hemisphere, they become North Trade Winds, and in the Southern Hemisphere, they are called Southeast Trade Winds.
- Trade winds blow at a constant speed and are regular.
- They are associated with constant depressions and cyclones.
- The Trade Winds are also known as permanent or constant winds. The only exception is that they are replaced by the monsoon winds in the Indian and Pacific oceans.
Westerlies
- They blow from Sub-Tropical High-Pressure Belts to Sub-Polar Low-Pressure Belts between 30° and 60°N of the Equator in the temperate latitudes.
- Because of the Coriolis Effect, they deflect to their right to become the South Westerlies in the Northern Hemisphere and deflect to their left to become the North Westerlies in the Southern Hemisphere.
- They are strong winds that are dominated by the movements of cyclones and anti-cyclones.
- They are responsible for carrying warm equatorial waters and winds to the western coasts of the temperate lands.
- Because of the shifting of the wind systems, not all the places located on the western coast of the temperate lands receive rainfall throughout the year.
Polar Easterlies
- Polar winds blow from the polar high-pressure belt towards the Sub-Polar Low-Pressure Belt between 60°N to 60°S. In the Northern Hemisphere, they blow from the northeast and are known as the Northeast Polar Winds. In the Southern Hemisphere, they blow from the southeast and are known as the Southeast Polar Winds.
- Because they are deflected in the west in both hemispheres by the Coriolis Effect, they are known as the Polar Easterlies.
- These are cold winds as they blow from the ice-capped regions. However, they become warm when they blow over the oceans.
Also, Read Pressure belts and types of winds