Cloud Stuffed with Rocks

"You know when we were flying and I was worried we might hit something in the storm and you said the only thing we could possibly hit at this height was a cloud stuffed with rocks?"
"How did you know?"
-- Terry Pratchett, The Light Fantastic

I'm a bit worried about all these proponents of The Cloud. Are they OK? Do they know what they are talking about? Maybe they haven't looked at the sky recently.

What I've seen in the sky are just levitating stone slabs being piloted by a well-trained teams of druids from Amazon and Google. If you are up to flying on a broomstick in the storm, be careful to avoid those clouds stuffed with rocks.