The wing studies the lift, so it studies the pressure difference between the upper and lower surfaces.
To study the horizontal movement of sand dunes, it is necessary to study the horizontal pressure difference. The windward wind speed is large and the pressure is small; The leeward side has low wind speed and high pressure, and the sand dunes move to the windward side.
The wind is blowing from the left. The left side has high speed and low pressure, so it moves to the left.