A wing flies to the left in the air (no wind). Particles A and B moves to the right in relation to wing.
In which direction do particles A and B moves in relation to the ground? What is velocity of particles in relation to the ground?
Don't forget, air is at rest (no wind) and the wing is moving, so why does particle C not move to the particle A, because the net pressure gradient is to the left and air always travels from high to low pressure?
(i think when observed from ground :
particle A moves up and left
particle B moves down and left
particle C moves down and left
and when wing pass all particles will move down and left)