Did you notice the lines in the sky during today's sunset? It's fairly common in Arizona. In fact, it's common enough to make the Arizona State Flag, but it's still always fascinating to see.
image: Tucson News Now - August 15, 2016 sunset
The lines in the sky are called "crepuscular rays". The tops of cumulus clouds are blocking some of the sun's rays as the sun gets lower in the sky. The result is a series of lines across the sky.
The word, "Crepuscular" derives from the Latin word, "crepusculum," which means "twilight."
image: Itzel - See it Snap it Send it
This image, sent to us by a viewer, is the same sunset as the first image, but looking the opposite direction. These lines are called "anticrepuscular rays", because the lines appear to be coming from the opposite direction as the sun.
You can catch crepuscular rays during sunrise or sunset, but it's more common during sunset since there are usually more clouds in the sky.