What is cool dense air that descends from the back of a storm called?

The cool, dense air that descends from the back of a storm is called a "downdraft." Downdrafts occur when precipitation falls and drags surrounding air downward, creating a pocket of cool air that rushes towards the ground. This process can lead to gusty winds and is often associated with severe weather events, such as thunderstorms. When downdrafts spread out upon reaching the surface, they can create a phenomenon known as a "gust front."