Downrushes

Downrushes are a meteorological phenomenon characterized by a sudden, localized downdraft of air. These events typically occur within cumulonimbus clouds, the same type of clouds that produce thunderstorms. A downrush is essentially a concentrated stream of air descending rapidly from the cloud base towards the ground.

The process begins within the thunderstorm cloud where precipitation, such as rain or hail, falls through the air. As these hydrometeors descend, they drag surrounding air downward with them. Evaporation of some of these falling particles can also occur, which cools the air and makes it denser, further accelerating its descent. This accelerated downward flow of air is what constitutes the downrush.

Upon reaching the ground, a downrush can spread out horizontally, creating a gust front. This gust front is often associated with a sudden increase in wind speed, a drop in temperature, and sometimes a shift in wind direction. While downrushes are a common feature of thunderstorms, they can vary significantly in intensity. Some are relatively weak, causing only a minor disturbance, while others can be strong enough to cause damage to property and pose a hazard to aviation. They are distinct from tornadoes, which involve rotating columns of air.