Rare, menacing roll cloud moves across northern Virginia (PICTURES)

Roll cloud viewed from intersection of Lee Highway and Shirley Gate Road in Fairfax around 7:50 am looking west. (Scott Kanowitz)

Roll cloud viewed from intersection of Lee Highway and Shirley Gate Road in Fairfax around 7:50 am looking west. (Scott Kanowitz)

On the leading edge of a cold front gliding through the D.C. metro region this morning, a scary-looking tube-shaped cloud stretched across the skies in northern Virginia. It ended up signaling mostly benign weather, in the form of some showers that followed its passage.

This cloud type is known as a roll cloud or arcus cloud.

Related: Clouds: The weirdest of the weird | Is that a tornado? Wall, scud, shelf and other scary looking clouds

Resembling a giant dough roller, a roll cloud is completely detached from its parent shower or thunderstorm.

“Sinking cold air causes warm, moist air on the planet’s surface to climb to higher altitudes, where the moisture condenses into cloud form,” explains Live Science. “Winds from the storm “roll” the cloud parallel to the horizon, creating an effect that looks much like a horizontal tornado.”

These clouds are relatively rare, less common than its cousin the shelf cloud, which often can be found along the leading edge of thunderstorms, forming along their gust fronts. Roll clouds seldom produce violent winds, whereas shelf clouds are sometimes a harbinger of severe weather.

Here is a large assortment of the roll cloud pictures, photographed by readers across northern Virginia this morning.

Roll cloud from Aldie, Va. (Stephanie Ross via Facebook)

Roll cloud from Aldie, Va. (Stephanie Ross via Facebook)

 

Roll cloud from Skyline, Alexandria (Cristina Rugo via Facebook)

Roll cloud from Skyline, Alexandria (Cristina Rugo via Facebook)

Roll cloud from Springfield, Va. (Erin Miller via Facebook)

Roll cloud from Springfield, Va. (Erin Miller via Facebook)

Roll cloud viewed from South Riding (Michael Duncan via Facebook)

Roll cloud viewed from South Riding (Michael Duncan via Facebook)

Roll cloud viewed from Bristow (Deve Mitchell via Facebook)

Roll cloud viewed from Bristow (Deve Mitchell via Facebook)

Roll cloud viewed from intersection of Lee Highway and Shirley Gate Road in Fairfax around 7:50 am looking west. (Scott Kanowitz)

Roll cloud viewed from intersection of Lee Highway and Shirley Gate Road in Fairfax around 7:50 am looking west. (Scott Kanowitz)

 

 

 

 

 

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