How are westerly and easterly winds formed?

In the northern hemisphere, any large fluid displacement such as the oceanic currents and the atmosphere, are subject to the Coriolis effect, due to the earth's rotation, that diverts it to the right-hand side. read more

All winds, be they easterly, westerly, or whatever are formed in the same way: pressure gradient forces associated with spatial differences in temperature through the depth of the atmosphere. On large scales (say, 1000 km, or more), a significant additional force plays an important role: the Coriolis force produced by the Earth’s rotation. read more

Prevailing westerly winds are a result of the direction of rotation of earth, and of how the atmosphere circulates. At the equator, earth's surface rotates at approx. 1,673 kmh (1040 mph). Normal surface wind speeds there average about 0 kmh, to the mass of the atmosphere is traveling from west to east at 1,673 kmh. read more

The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend towards the poles and steer extratropical cyclones in this general manner. read more