Cumulus is probably what you'd draw if someone asked you to draw a cloud. They generally look like piles of cotton – indeed, ‘cumulus’ is Latin for ‘heap’ or ‘pile’, which is where the English word ‘accumulate’ comes from. They usually develop close to the Earth's surface, but grow when heated from below. Some cumulus even turn into...
Cumulonimbus result from powerful currents of rising air – some cumulonimbus can grow up to ten miles tall! They grow so high that they actually bump up against the next highest layer of the atmosphere, where it's so cold that the tops are made if ice crystals instead of liquid water. Strong winds blow the icy cloud tops downstream, creating an ‘anvil’ like you see here. Cumulonimbus bring rain and thunderstorms; and occasionally a cumulonimbus can continue to develop into a supercell.