Two different optical effects are visible: One in the sky, another one on the ground. The sky shows anti crepuscular rays, on the ground you can see an opposition effect. Opposition effect: The lighted round area surronding my shadow head. For informations about the opposition effect use this adress: http://www.meteoros.de/oppo/oppoe.htm Anti crepuscular rays: A variant of cloud shadow rays. When the sun is very low close to the horizon, the shadow rays can extend over the whole sky (crepuscular rays) and converge at the antisolar point (anticrepuscular rays). This effect is a close relative to the "spectra of brocken"