Great Lakes Region, State of Michigan, USA

STS040-77-045 (6 June 1991) --- This image, photographed on June 6, 1991, is an oblique view looking north-northeast and shows most of the Great Lakes region. Part of Columbia's cargo bay and the Spacelab Life Sciences (SLS-1) module are in the foreground. In the center of the image is Lake Michigan with Chicago clearly visible along the southwest shore. According to NASA photo experts studying the STS-40 imagery, this image shows several interesting meteorological phenomena. The difference in temperature between the warming land and the cold lake waters is illustrated by the low level clouds. The warming land surface results in rising air and the formation of clouds, while the lake waters are cold and result in the lakes remaining cloud free. Also visible is evidence of lake breezes developing around several of the lakes. This phenomena is also driven by the difference in temperature between the land and the water. Winds blowing off the lakes must travel 25 - 30 miles inland before it warms sufficiently to create clouds.