Mammatus Clouds

Severe thunderstorms rolled through western North Carolina on the evening of June 7, 2011. Though we were spared the worst of the wind and rain, ominous looking mammatus clouds glared down at storm’s end.   Photographer Rich Bruner

Whenever mammatus clouds are observed, it’s recognized that downdrafts of cool air are an active feature of the storm system.

The orange color of the clouds is attributed to a low Sun. Sunlight has been attenuated by the greater path-length that occurs when the Sun lies near or below the horizon. Here, the Sun has already set (at the surface), but the lofty clouds are still exposed to the Sun’s lingering rays.