The Nervous Passengers' Guide to Flying, by Tug Wilson

   

 

"This beast of a cloud is the thunderstorm" (P 81)

 

 

Finally, the mother of all cloud dramas - the Cumulonimbus. This beast of a cloud is the thunderstorm. Some of them reach up above 30,000 ft and have horrific up-draughts and, more importantly, downdraughts. These can be in the region of 10,000 feet per min rate of climb/descent, which is like the worst roller coaster you've ever been on. It just feels horribly bumpy when you fly through them and pilots will happily re-route for miles to avoid them.