Morning Glory lures scientists to ride cloud nine

By Deborah Smith, Science Writer
The Sydney Morning Herald
September 16 2002

What's the story? . . . the Morning Glory cloud rolls majestically above Burketown. Photo: Roger Smith

The season for Morning Glory cloud formations has just begun in the Gulf of Carpentaria and glider pilots and scientists are heading north to ride the spectacular waves.

The Gulf is the only place in the world where this meteorological phenomenon - a rolling cloud up to 1000 kilometres long, stretching from horizon to horizon - occurs with predictable regularity from September to November.

From the front, the cloud, one to two kilometres high, appears to roll backwards as it advances across the Gulf at about 40 kilometres an hour.

It gets its name from its arrival time on shore, at dawn, near the remote community of Burketown in western Queensland.

A Morning Glory cloud is mathematically known as a solitary wave - a single crest that moves without changing its shape or speed. Solitary waves occur in the atmosphere elsewhere, says Jorg Hacker, of Airborne Research Australia in Adelaide. They are usually invisible, however, because they carry no cloud. "But in the Gulf, the humidity is just right to generate this impressive phenomenon."

Next month, Professor Hacker will be part of a scientific expedition to study the Morning Glory, as well as other unusual Gulf clouds, with researchers drawn from Flinders and Monash Universities and the Bureau of Meteorology Research Centre. Long time Morning Glory observer, Australian-born Dr Roger Smith, of the University of Munich, will also return this year.

Computer simulations suggest that a Morning Glory is caused by the collision of two sea breezes over Cape York the preceding evening. "We want to nail down the mechanism that triggers these clouds and then see how they interact with large scale weather patterns in the region," Professor Hacker said. "We want to understand the physics behind it, so we can forecast it."

Russell White, of Byron Bay, was one of two glider pilots who pioneered the art of soaring on a Morning Glory in 1989. He has returned every year since. "It is the most fabulous experience. There is nothing like this in the world," he said.

Turbulence and down-draft make flying behind the cloud dangerous, but the strong updraft at the front of the wave makes it possible for the glider to zigzag across it, "very much like surfing on a board". Some trips last several hours and can cover more than 300 kilometres.

Amanda Wilkinson, who owns Savannah Aviation at Burketown, said the season had already
started, with three Morning Glories in the past fortnight.

©The Sydney Morning Herald
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