Warm water heats the air causing it to rise really quickly, then it gets pushed aside as it cools.
This pushing causes the clouds to spin.
When does it become a hurricane?
Hurricanes are tropical storms where the winds get faster than 118 km/h (73 mph).
The storms have a central area of calm known as the "eye", which is the funnel through which the warm air rises.
Overland, the storms no longer have warm water to power them and die out within a few days, but not before winds do a lot of damage.