Wednesday, August 26, 2009
Cool:
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.
Similar tubular shaped clouds called roll clouds appear in various places around the globe. But nobody has yet figured out what causes the Morning Glory clouds.
This shot was captured by photographer Mick Petroff from his plane near Australia's Gulf of Carpenteria.
My first thought was a jet stream anomaly was the probable cause.
really large contrail caused by really large jet- on-steroids?
Apparently these clouds also appear in the Midwest
Amateur meteorologist Alan Sullivan explains:
These clouds are fairly common in the American Midwest, and anywhere else in the world that severe thunderstorms occur — northern Australia gets some lively action in spring and summer. I have seen them many times, in person and on satellite images, during my decades of cloud-watching.
“Morning glory clouds” always form in the same distinctive circumstances, after a night of violent thunderstorms. Such storm complexes can cover a large area for a time, and they often dissipate abruptly, just before dawn. The collapse of ten-mile high cumulonimbi can cause a mighty disturbance in the atmosphere — a pressure wave, radiating out from the collapse, often traveling hundreds of miles in a few hours.
In a moist morning atmosphere, the pressure wave will generate a set of roll clouds as it moves forward. They take their shape from the force that forms them. They move at high speed because they are not moving with any wind. They simply propogate through the calm morning air. Such roll clouds often signal more severe weather for the afternoon or evening in the area where they are seen, or further downstream.
Very interesting...