We just learned about Shelf Clouds.
Another type of storm cloud is called a Roll Cloud.
It is a low tube shaped cloud that is usually all by itself and not connected to any other clouds.
They look like they are rolling along the sky, like a long tube.
![roll cloud](https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Roll-Cloud-Racine.jpg/640px-Roll-Cloud-Racine.jpg)
(from: wikipedia - arcus cloud)
Kid Facts - Blast from the past: Pumice