MADISON, Wis. (WMTV) Take a look at this photo of a roll cloud sent into us by a viewer in Green County!
This might feel like déjà vu after Thursday's storms rolled through. Many of you sent in photos of a weird wedge like cloud. This was a shelf cloud (below). Today's roll cloud may look similar to the shelf cloud but there's a small difference.
Both of them are formed along the leading edge of a line of showers/storms. Both of them accompany strong gusty winds and heavy downpours. The difference is that a shelf cloud is attached to the base of the storms cumulonimbus cloud, whereas a roll cloud isn't.
The roll cloud is formed by warm air rising ahead of the storms outflow. The warm air then cools, condenses forming a cloud. As it rises, it meets up with strong winds that come from the opposite direction. This is what we call wind shear. This creates a spinning motion in the cloud, thus why its called a roll cloud.
Both a shelf cloud and roll cloud share similarities, and they both means strong storms are heading in your direction. If you see any clouds that look like these you need to head indoors.