Sunrays before sunrise or after sunset
http://earthsky.org/tonight/sunrays-before-sunrise-or-after-sunset
Before sunrise or after sunset, you might be gazing skyward and notice that there are beams of light that appear to be shooting out from horizon, or down from the clouds. These are crepuscular rays, sometimes called sunrays. They are beautiful, mysterious and very noticeable.
You need just the right conditions to see these rays. In order to see them, the clouds, the sun and you must all be in the right spot with respect to each other. Crepuscular means like twilight or dim. That’s a clue that this effect is normally 1.-seen before sunrise or just after sunset, when the 2.-sky is somewhat dark.
When you see the rays, the sun’s disk might be just below the horizon from your perspective with the sun is shining through clouds in that part of the sky. The clouds scatter the sunlight, creating the rays.
Image Credit: Mila Zinkova via Wikimedia Commons
If you are seeing these rays in the east before dawn, remember to turn around and face west. You might be in luck and see anticrepuscular rays. These rays form opposite the sun. The rays are split apart by the clouds so they come back together on the opposite side of the sky. They are sort of like the lines on a basketball spread apart from the top of the ball and coming back together on the bottom. If you are noticing the rays at sunset, turn around to the east to see the anticrepuscular rays.
