Which force opposes the downward force of weight in an aircraft?

In the context of aircraft, the force that opposes the downward force of weight is lift. Lift is generated by the wings as air flows over and under them, creating a pressure difference that allows the aircraft to rise. This upward force must be sufficient to counteract the weight, which is the gravitational force acting on the aircraft, in order for the aircraft to climb or maintain level flight.

Understanding lift is crucial in aerodynamics, as it plays a fundamental role in the aircraft's ability to become airborne and maneuver in the air. Factors that affect lift include the shape of the wings (airfoil), the angle of attack, and the velocity of the aircraft relative to the air. When the lift is greater than weight, the aircraft ascends; when lift is equal to weight, it maintains altitude; and when lift is less than weight, the aircraft descends.