viernes, 12 de octubre de 2007

Gravity wave

On October 3rd, a train of giant waves rippled across the skies of Des Moines, Iowa, in view of Iowa Environmental Mesonet video cameras. Click on the image below to play the movie:

Movies: 5 MB mov, 5 MB gif, 13 MB gif.

This is a special kind of atmospheric gravity wave called an "undular bore." Researchers believe undular bores may be more common and more important then previously thought. Among the things they can do: collide with tornados and spin them up, turning ordinary twisters into F5 monsters. "An undular bore passes over any given point in the United States about once a month," estimates Tim Coleman of the National Space Science and Technology Center in Huntsville, Alabama.