These long, crazy-looking clouds can grow to be 600 miles long and can move at up to 35 miles per hour, causing problems for aircraft even on windless days.

Known as Morning Glory clouds, they appear every fall over Burketown, Queensland, Australia, a remote town with fewer than 200 residents. A small number of pilots and tourists travel there each year in hopes of “cloud surfing” with the mysterious phenomenon.

Through research, one of the main causes of most Morning Glory occurrences are due to the mesoscale circulations associated with sea breezes that develop over the peninsula and the gulf. On the large scale, Morning Glories are usually associated with frontal systems crossing central Australia and high pressure in northern Australia. Locals have noted that the Morning Glory is likely to occur when the humidity in the area is high, which provides moisture for the cloud to form, and when strong sea breezes have blown the preceding day.

Similar phenomena also occur over the Central United States, the English Channel, over Berlin, Germany, Eastern Russia, as well as other maritime regions of Australia, but only the ones over Burketown are predictable at a certain time of year.

They are made by waves in the atmosphere known as “gravity trains” and behave rather like waves from a boat. When a boat tears across a lake, water in front of the boat is pushed upward. Gravity pulls the water back down again and this sets up a wave. Usually we cannot feel these gravity waves in the atmosphere because air is far less dense than water, but you are definitely aware of them in an aircraft when they make for a very bumpy ride, in clear-air disturbances, although usually without clouds.

Such rolls clouds are best known in northern Australia as the “Morning Glory”. This is one of the world’s greatest weather phenomena. Around this time of year, the Morning Glory rolls in near dawn as one or more tubular clouds rapidly advances low across the Gulf of Carpentaria, northern Queensland. It can span the entire horizon in a spectacular display up to 1,000km (620 miles) long. And because the cloud rides on a gravity wave in the atmosphere, it has become a magnet for gliders and microlights to ride like a surfer riding a wave. It is claimed to be one of the most exhilarating experiences in gliding.