The first object of the painter is to make a flat plane appear as a body in relief and projecting from that plane
Leonardo da VinciIf you are on the side whence the wind is blowing you will see the trees looking much lighter than you would see them on the other sides; and this is due to the fact that the wind turns up the reverse side of the leaves which in all trees is much whiter than the upper side.
Leonardo da Vinci