Kelvin-Helmholtz Clouds and Space Needle
September 08, 2008
While photographing a late winter dawn in Seattle, Washington, I was pleasantly surprised to see these Kelvin-Helmholtz (K-H) wave clouds silhouetted against the brightening sky. The Space Needle is in the foreground. The leading edge of high cirrus clouds from an approaching Pacific weather system were just arriving at the time. These K-H waves appear to have formed in the lee of Mt. Rainier, about 60 miles (100 km) south-southeast of Seattle which is just out of the image to the right. When you spy such clouds, you can be sure that a significant wind shear is present aloft -- their formation is governed by wind shear (velocity difference) between adjacent cloud layers. Photo taken on March 6, 2006.