On a recent crisp autumn afternoon in Iowa, video cameras captured an unusual and visually dramatic result of two air masses colliding. Clouds split into a series of stripes and swept across the sky.
These so-called undular bores are created by atmospheric conditions that destabilize the air in a particular way. In the case of Des Moines, Iowa, they formed on Oct. 3 when a group of thunderstorms approached the city.
"At the time, a layer of cold, stable air was sitting on top of Des Moines," said atmospheric scientist Time Coleman of the National Space Science and Technology Center in Alabama. "The approaching storms disturbed the air, creating a ripple akin to what we see when we toss a stone into a pond."
A time-lapse video of the event shows just how strange it looked. http://www.livescience.com/php/video/player.php?video_id=071012UndularBores
Undular bores are a type of gravity wave, one in which gravity is the force that pulls the wave down. Coleman likens the cloud waves to those created when a boat moves across the water.
No comments:
Post a Comment