Wind energy is the kinetic energy of the air in motion. Total wind energy flowing through an imaginary area A during the time t is:
E = A·v·t·ρ·½ v2,
where v is the wind velocity and ρ is the air density. The formula presented is structured in two parts: (A·v·t) is the volume of air passing through A, which is considered perpendicular to the wind velocity; (ρ·½ v2) is the kinetic energy of the moving air per unit volume.
Total wind power is:
P = E/t = A·ρ·½ v3
Wind power is thus proportional to the third power of the wind velocity.