The Occurrence of Lift Force

Aircraft are most concerned vehicle to the lift force.

Aerodynamics force caused by air across the aerofoil. Lift force, including part of the aerodynamics force. Airfoil is the cross section of aircraft wings. Air when passing the airfoil is shown in the figure below.

Air trajectories when moving through the airfoil is shown in the picture above. The air over the airfoil moves faster than the air under the airfoil because of the air over the airfoil travel longer distances with the same time with the air under the airfoil. Bernoulli equation is as follows: p + ro * g * h +0.5 * ro * V ^ 2 = constant. Assuming h above and below the airfoil equal value, in order to obtain the air pressure below the airfoil will be greater than the air pressure above the airfoil.