From Glossary of Meteorology


(Also called opposing wind.) A wind that opposes the intended progress of an exposed, moving object, for example, rendering an airborne object's airspeed greater than its groundspeed; the opposite of a tailwind.

This effect is particularly critical in air navigation; it is of interest to note that a wind direction may have no component opposing the intended course of an aircraft, but because of drift effects, may have a component opposing the aircraft's heading.