Definition
The upward deflection of air ahead of and around a wing as it moves through the air, caused by the wing's circulation pattern. Upwash occurs in front of the wing and along its outer edges, where air is drawn upward before flowing over and around the wing.
Plain English
As a wing moves forward, it pulls some of the air ahead of it slightly upward before that air actually reaches the wing. That upward motion of the air is called upwash.
Context Anchor
Seen in discussions of ground effect during takeoff, where the runway changes the airflow pattern around the wing close to the ground.
Derivation
A simple compound: 'up' (the direction) plus 'wash,' which in aerodynamics means a flow of air pushed by a wing or propeller. So upwash literally means air being washed upward by the wing's influence.
Why Pilots Care
Upwash is altered by ground effect, which reduces induced drag and increases lift at very low altitudes, directly affecting takeoff performance and climb.
Grounding Statement
Picture a wing slicing forward through still air: just ahead of the leading edge, the air lifts slightly upward to meet the wing rather than waiting to be struck by it.
Intuition Check
Upwash does not mean any upward gust of wind. Here it means upward-moving air created by the wing’s own lift-producing airflow.
Example Sentence 1
Close to the ground, upwash ahead of the wing is reduced, which is one reason the airplane behaves differently in ground effect.
Example Sentence 2
As the airplane climbed out of ground effect, the normal upwash pattern returned and induced drag increased.