A Stall

A stall is a condition where the airflow separates from the wing, increasing drag and reducing lift such that the aircraft can no longer sustain level flight.

At low angles of attack, the separation point of the airflow from the aerofoil is towards the rear and a turbulent wake is not significant.

However, as the angle of attack is increased, the separation point moves forwards and the turbulent wake is larger.

A stall occurs when the critical angle of attack is exceeded and can occur at any airspeed.