What is 'ground effect'?

Ground effect refers to the aerodynamic phenomenon that occurs when an aircraft flies close to the ground, typically within a distance equal to the wingspan of the aircraft. In this situation, the airflow around the wings is altered due to proximity to the ground, which can lead to an increase in lift and a decrease in drag. This effect is most noticeable during takeoff and landing, where pilots may experience a sensation of floating as the aircraft approaches the runway, making it easier to become airborne or to cushion a landing.

The increase in lift is primarily attributed to the reduction in downwash and wingtip vortices caused by the interference of the ground with the airflow over the wings. The decrease in drag is a result of lesser induced drag at low altitudes and speeds. Consequently, this phenomenon allows pilots to use less power to maintain altitude when approaching the ground, influencing their landing techniques and taxiing.

Other options do not accurately describe ground effect. For instance, while turbulence can occur during landing, it is not specifically linked to ground effect. The reduction of visibility due to obstacles is a different concern, unrelated to ground effect. Additionally, dividing an aircraft's total weight is more about balance and weight distribution, not an aerodynamic effect related to flying close to the surface.