photo #7321201

Clouds can operate on a scale only visible from the perspective of satellites. This huge ring of Cumulus clouds was spotted by equipment aboard NASA’s Terra satellite over the Pacific Ocean south-west of the Hawaiian Islands. The pattern of low clouds would not have been noticeable from a boat for the ring stretched across more than 250 miles (400 kilometres). The cause is not obvious but is likely related to larger clouds, now dissipated, that formed in the middle before releasing their showers and dissipating away. Cool air dragged down with the now-past precipitation would have spread outwards in all directions at the ocean surface. This dense cool air might have burrowed beneath the less dense warmer, moister air at the surface, lifting it to form an ever-expanding band of Cumulus clouds. Even after the shower clouds in the middle had dissipated, the circle of Cumulus remained and maybe continued to expand in a formation so broad it was hidden from all but a cloudspotting satellite.