the story? . . . the Morning Glory cloud rolls majestically above Burketown.
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
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.
Sydney Morning Herald
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