English: Fog and sunrise in a pine tree. This is an optical phenomenon involving crepuscular rays, rather than a physical fire. The explanation for this burning bush is a thin and localised fog in a pine tree, with an otherwise clear sky, and a bright sun close to the horizon. The beams of light are created by gaps between the branches, and the fog makes the light beams visible without being thick enough to obscure them completely. Small movements of viewing perspective cause the beams to change and appear to move. The beams of light coming from the tree are all parallel, but the viewer's perspective creates a parallax effect whereby the beams seem to diverge outwards.