Awesome Shelf Cloud Thrills Sky-Gazers in Iowa and Minnesota

Brian Donegan
Published: July 10,2016

Shelf cloud over Rushford, Minnesota, Sunday morning, July 10.
(Arlene and Gordon Johnson/Facebook)

Residents of Iowa and Minnesota were treated to an incredible sight Sunday morning as a squall line of thunderstorms produced a shelf cloud sweeping through portions of those states.
The photo above, from Rushford, Minnesota, is like a scene straight out of a movie.
You probably understand why this is one of the most frequently-shared weather photos we get on our Facebook page and in our weather.com/photos gallery. Here's how it looked near Grundy Center, Iowa.

Shelf cloud south of Grundy Center, Iowa, Sunday morning, July 10.
(Podunker/Twitter)

And, here's a picture of the same shelf cloud just a few miles to the northeast in Dike, Iowa.

Shelf cloud in Dike, Iowa, Sunday morning, July 10.

This shelf cloud also made an appearance a few miles to the northwest of there, in Parkersburg, Iowa.

Shelf cloud in Parkersburg, Iowa, Sunday morning, July 10.

Now, you're probably wondering what causes these shelf clouds.

Shelf Cloud Science

A shelf cloud is the boundary between a downdraft and updraft of a thunderstorm or line of thunderstorms.
(MORE: Incredible Shelf Cloud Wows Beachgoers on the Alabama Coast)
Rain-cooled air descends into a thunderstorm's downdraft, and then spreads out laterally when reaching Earth's surface. Warmer, more moist air is lifted at the leading edge, or "gust front," of this rain-cooled air.

The meteorological factors behind the formation of a typical shelf cloud.