Tangentially related to my previous post about the aurora borealis.
Weather
31
Aug 11
What is a Roll Cloud?
A roll cloud rolls through the sky on a horizontal axis. It looks kind of like a tornado turned on it’s side, but it’s not. It poses no danger of a tornado at all. You can read more and get a larger resolution pic here: http://apod.nasa.gov/apod/ap110831.html
It certainly looks like a burly beast. I saw something like this in Birmingham, Alabama. As it turns out the clouds I saw are a little bit similar, but are formed under different conditions. What I saw was called a cumulonimbus mamma, or mammatus clouds. Beautiful and scary. Check out the pics and description over at Wikipedia: http://en.wikipedia.org/wiki/Mammatus_cloud