I was thinking about clouds today, and wishing I knew more about them.

Of course I know what a cloud is. I recognise a cloud when I look up into the sky and there's one there. But I want to know more - like how it forms. The structure of the cloud, how the water vapour holds together, the different names for the clouds, how much vapour they hold when they are at different altitudes. And, of course, the ultimate cloud question that has must've dogged scientists forever: how clouds know how to form into the shapes of fluffy bunnies, teddy bears and trains.