Cloud shadow over Las Vegas
What you see here is the shadow of a cloud, captured over Las Vegas, Nevada, by Bettina Berg on October 1, 2018. The great sky optics expert Les Cowley – of the website Atmospheric Optics – calls them the inverse of crepuscular rays and notes they can produce dramatic effects. I asked Les about Bettina’s photo, and he wrote:
A remarkable sight.
There is a combination of (1) a low sun, (2) a widespread layer of high cloud and (3) a towering cumulus that just breaks through the cloud layer. The cumulus top is casting its shadow down onto, or along, the cloud layer making the latter dark.
Check Les’ website for a diagram that explains more about cloud shadows here.
Bottom line: Cloud shadow over Las Vegas on October 1, 2018.