Dihedral+Angle

The Dihedral angle is the angle that each wing makes with the horizontal. The whole purpose of the Dihedral angle is to improve the lateral stability. If a disturbance cause one of the wings to drop, the unbalanced forces produces a sideslip in the direction of the down-going wing. This will cause a flow of air in the opposite direction of the sideslip. This Flow of air will strike the lower wing at a bigger (greater) angle of attack than it strikes the upper wing. The lower wing will receive more lift and the airplane will roll back into its proper position.



Here is a picture to help you understand it better.( if needed) ->