Shelf clouds form when a solid line of storms approaches an area. In these clips, a variety of shelf clouds churn across the horizon in an awe-inspiring display of natural power.
A squall line is a meteorological term for when a group of storms forms a line as they move through the area. Usually, this squall line is indicated by a shelf cloud, an impressive sight that speeds across the horizon as the storms themselves approach.
Some of these shelf clouds can rotate, which then leads to tornados. Whether it is rotating or not, a shelf cloud is an indication that strong storms are moving through the area and a sign that you need to take shelter immediately or risk harm.