Every year, more than 400 waterspouts appear in the seas around the Florida Keys. These funnel-shaped clouds form above the surface of the water and spin upwards in a vortex towards the cumulus clouds above. Sometimes more than 600 metres tall and tens of metres in girth, they normally last only 20 minutes. Waterspouts have been known to suck fish up from sea, rivers or lakes into the clouds. Last summer, children at a school in northern California found dozens of tiny fish scattered across their playground and school roof. Waterspouts were deemed the culprits.