Wiki Wednesday #22

29 08 2007

1.) Go to Wikipedia.
2.) Click on “Random article.”
3.) Report on the outcome.

Morning Glory cloud

The Morning Glory cloud is a rare meteorological phenomena observed in Northern Australia’s Gulf of Carpentaria. A Morning Glory cloud is a roll cloud that can be up to 1000 kilometers long, 1 to 2 kilometers high, and can move at speeds up to 40 kilometers per hour. The morning glory is often accompanied by sudden wind squalls, intense low-level wind shear, a rapid increase in the vertical displacement of air parcels, and a sharp pressure jump at the surface. In the front of the cloud, there is strong vertical motion that transports air up through the cloud and creates the rolling appearance, while the air in the middle and rear of the cloud becomes turbulent and sinks. The cloud can also be described as a Solitary wave or a Soliton, which is a wave that has a single crest and moves without changing speed or shape.

Now, if you’re like me, that definition left you curious—but without any idea what this thing actually is. Or looks like. I found the entry for “roll cloud” to be helpful:

Roll cloud

A roll cloud is a low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front, or sometimes a cold front. Roll clouds can also be a sign of possible microburst activity.

Roll clouds are relatively rare; they differ from shelf clouds by being completely detached from the thunderstorm base or other cloud features. Roll clouds usually appear to be “rolling” about a horizontal axis.

Wikipedia offers a very cool picture of a roll cloud, too, although it’s one from Wisconsin, not Australia. Here and here are some of the best pictures I could find of the actual Australian Morning Glory. Wow! Apparently, people can hang glide in (on?) the Morning Glory. That sounds both totally interesting as well as absolutely terrifying.

According to the Wikipedia entry, “similar” Morning Glory-type formations have been reported elsewhere. This page describes a Morning Glory that formed near Nova Scotia in 2003.

Have I ever mentioned that my childhood ambition was to be a meteorologist. I wonder if I would’ve actually enjoyed that as a profession….

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