FILE photo - Richard Heath/iStock(ROANOKE, Va.) -- A Virginia resident captured a rare cloud formation hovering over the skyline near her home.

Amy Christie Hunter posted a photo of the wave-shaped clouds to Facebook on Tuesday evening. In the image, they can be seen rolling over Smith Mountain near Roanoke.

The formation is known as the Kelvin-Helmholtz cloud, and is named after the scientist who studied the physics behind them.

The clouds are rare and usually form during windy days when there is a strong vertical shear — meaning the wind is blowing faster at upper levels in the atmosphere compared to the wind at lower levels, causing the clouds to look like rolling waves.

Weather conditions in the area Tuesday evening included light rain and fog.

Copyright © 2019, ABC Radio. All rights reserved.