This mighty Cumulonimbus storm cloud seems to be topped with a spiky Mohican hairdo. It has pushed into the upper reaches of the troposphere, thanks to its powerful updrafts, and there its upper parts have frozen into ice crystals that give it a hairy appearance. This is why this species of Cumulonimbus is known as capillatus, from the Latin meaning ‘having hair’. The ice crystals spread out at the top to form the storm cloud’s incus, shaped like a blacksmith’s anvil (which is what the Latin name means), as it reaches the top of the troposphere, where clouds can rise no further. Raymond Popkin (Member 63,500) watched from the beach at Boca Raton, Florida, US as the storm grew and died, breaking up as its showers dissipated below and the crepuscular rays of dawn broke through.