downdraft

A downdraft is a downward-moving column of air that originates in the atmosphere and accelerates toward the ground. It develops when air becomes negatively buoyant or is cooled by processes such as evaporation of precipitation or entrainment of drier air, causing the parcel to become denser than its surroundings. The result is a rapid descent that can reach the surface as a gust of wind.

Downdrafts commonly occur in strong convective storms, including thunderstorms. Within a storm, rain-cooled air that descends as rain evaporates can form a wet downdraft, while evaporation of falling precipitation and mixing with dry ambient air can produce a dry downdraft. Both can drive a gust front when the descent reaches the surface, displacing ambient air and spreading out in a wedge-shaped boundary.

At the ground, intense downdrafts can generate damaging winds known as downbursts or microbursts, particularly in the case of localized, powerful downdrafts. These winds can threaten aviation and ground infrastructure and are a major hazard associated with severe storms. Doppler radar and weather satellites help identify downdraft activity through rapid changes in wind velocity and precipitation patterns.

Downdrafts are part of the broader thunderstorm circulation, usually balanced by updrafts that supply moisture and buoyancy. Understanding their development helps forecast storm severity and potential wind-related damage.