St. Cloud Roll Cloud

January 11, 2011

Photographer: Jon Zenzel
Summary Author: Jon Zenzel; Jim Foster

This nasty looking roll cloud is taking dead aim at the St. Cloud Middle School in St. Cloud, Florida. Since it seems to be separated from clouds above it, it's referred to as a roll cloud. A shelf cloud is, in essence, the same as a roll cloud, but it's connected to an obvious parent cloud. The picture was taken at 5:52 p.m. on June 3, 2010, during the after-school program I run. Fortunately, the storm wasn't as dangerous as it appeared; there were only minor wind damage and no injuries.

Old Glory snapping in the wind gives a strong clue that this cloud is not associated with a tornado. The wind is blowing in the direction that the storm is moving and not towards it, as would be the case with a tornado. However, because roll clouds are sometimes observed to rotate along their horizontal axis, they're indeed unnerving.

Photo Details: Camera: Apple iPhone 3GS; Focal Length: 3.9mm; Aperture: f/2.8; Exposure Time: 0.0011 s (1/918); ISO equiv: 70.