Downwash

Downwash is the column of air that a rotor, propeller or wing pushes downward to produce lift. Under a hovering aircraft it can be strong enough to kick up dust, flatten grass and cool or disturb anything sitting below the rotors. Rotor wash is another name for the same airflow under a helicopter or drone.

Example: When a helicopter lands in a dirt field, the cloud of dust blown outward is caused by its downwash.