Burketown in northern Queensland, Australia has a cloud visitor, known locally as the Morning Glory cloud, which appears in the spring months of October and November in the form of a long, travelling roll of low cloud. As its name suggests, the cloud arrives at daybreak, but it forms at the end of the previous day and travels through the night to get there.

The cloud formation begins life in the collision of sea breezes over the Cape York Peninsula, across the Gulf of Carpentaria in the north-east of Australia. During the heat of the previous afternoon, sea breezes are drawn into the peninsula from the Coral Sea to the east and the Gulf of Carpentaria to the west. And when these sea breezes collide – known by the meteorological term convergence – they cause atmospheric waves to travel south-west through the stable low air over the Gulf of Carpentaria. These are often solitary waves – individual rising and dipping crests of air that progress through the night and reach the small settlement of Burketown early the next morning.

Usually, a solitary wave of rising and dipping air like this is invisible and so arrives unnoticed. But in the spring months, when the area’s humidity is high, the rising air in the middle of the wave can form into a dramatic roll of low cloud, like this one spotted by John Riedl earlier this year. The Morning Glory cloud can extend a massive 600 miles (700 km) from end to end. It rolls in a rather counterintuitive way, lifting at the front and dipping at the back as it travels at speeds of up to 40 mph (60 km/h).

The formation is a major attraction for glider pilots like John Riedl. That’s because they can surf the rising air just to the front of the travelling cloud just like regular surfers on an ocean wave. Sometimes, the waves are not so solitary, and a group of Morning Glory clouds roll in, one after another, letting the airborne surfers ride one wave after the next as they jump from crest to cloudy crest.

A Morning Glory cloud, known more officially as Stratocumulus volutus, spotted by glider pilot John Riedl over the coastal waters near Burketown, Queensland, Australia. View this in the photo gallery.