Clouds, even the small fluffy ones, are surprisingly light and don't weigh much at all.

That's actually false! Even though clouds look light and airy, they're made of millions of tiny water droplets or ice crystals. An average cumulus cloud – one of those white, fluffy clouds you often see in summer – can weigh as much as 100 elephants put together! They stay up thanks to warm air currents that lift them.