Formal balance is present when two shapes of equal size are found on both sides of the painted area. Asymetric balance is achieved when a large shape, probably in the foreground, is counter balanced by several smaller shapes on the other side of the paper or canvas. Asymetric balance is usually more desirable in landscape painting.
In "Fog at Ocean Point", the large tree on the right is balanced by the smaller trees on the left. The intervals and direction of the trees is important to clearly separate the two areas, making the balance noticeable.
When planning repeated shapes or objects, like trees, houses, groups of animals, remember to take balance into consideration for a satisfying result.