easterlies

Easterlies are winds that blow from the east toward the west. In meteorology, the term is used to describe broad-scale wind patterns that occur in two main regimes: tropical easterlies near the equator and polar easterlies at higher latitudes. In mid-latitudes, prevailing winds are typically westerly, not easterly.

Tropical easterlies, also known as the trade winds, dominate roughly between 30 degrees north and 30 degrees south latitude. They arise from the global Hadley circulation and the subtropical high-pressure belts, producing a persistent east-to-west flow. In the Northern Hemisphere they are generally northeasterly, while in the Southern Hemisphere they are southeasterly. These winds drive warm surface currents toward the western sides of oceans and influence tropical rainfall patterns, coastlines, and the formation of monsoon systems. Their intensity and position vary with season and large-scale climate oscillations.

Polar easterlies occur from about 60 to 90 degrees latitude in both hemispheres. Cold air over the polar regions moves toward lower latitudes and, affected by the Coriolis force, becomes an easterly wind—blowing from the east to the west. These winds are usually weaker and more variable than tropical easterlies and interact with mid-latitude westerlies to shape storm tracks and winter weather. They contribute to the transport of polar air toward lower latitudes.

Easterlies are a foundational component of global atmospheric circulation and have significant implications for climate, ocean currents, and aviation.