Then they notice a cloud formation that looks like a dolphin, or a boat, or letters of the alphabet. But few are fortunate enough to see Kelvin-Helmholtz clouds, which look like a pattern of ocean ...

Known as Kelvin-Helmholtz clouds, they form when a faster stream of air moves above rising air below. According to the Met Office website, Kelvin-Helmholtz clouds are "an extremely rare phenomenon".

Kelvin Helmholtz clouds are named after the two scientists who studied the physics behind them A rare cloud formation resembling waves in the sky has been seen across North Yorkshire. The billowy ...