Contrasting Cloud Decks

April 07, 2005

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Provided and copyright by: Walter Handy
Summary authors & editors: Jim Foster; Walter Handy

Early in the morning of February 26, 2005, I was driving on Route 40 between Grande Prairie and Grande Cache in Alberta, Canada and encountered this fascinating, contrasting cloud formation. Rt. 40 runs along the eastern front of the Rocky Mountains. These cloud decks are almost perpendicular to each other. The more dense appearing cloud bank in the background is the backside of a system that was moving in a south-south-easterly direction, along the flank of the Rockies. While it's difficult to ascertain the exact nature of these clouds from this one photo, they're likely altostratus and may have formed orographically as moist air climbed over the Rockies -- from west to east. Further from the horizon, and higher in altitude than the altostratus, cirro-stratus clouds seemingly fan out from the altostratus deck. These wispy clouds are perhaps associated with a branch of the polar jet stream.

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