Westerlies
Also called: Prevailing westerlies · Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"; Class 11, Ch 10 "Water in the Atmosphere"; Class 11, Ch 11 "World Climate and Climate Change"
Meaning
The westerlies are planetary winds that blow from the subtropical highs towards the subpolar lows, between about 35° and 60° latitude. The Coriolis force bends them. So they come from the south-west in the Northern Hemisphere and from the north-west in the Southern Hemisphere. They bring rain and cyclones to the west coasts of continents in middle latitudes. They also bring winter rain to Mediterranean lands. In the Southern Hemisphere there is almost no land at 40–50°S to slow them. So they blow strong and steady there and are called the Roaring Forties.
Example
The westerlies bring heavy rain to the coasts of British Columbia (Canada), north-west Europe, southern Chile and New Zealand.
Don't confuse with
- Subtropical westerly jet stream: a narrow band of very fast wind about 12–14 km up, near 30°. It is not the surface westerly wind belt.