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Great Lakes
This image shows an interesting cloud pattern around the Great Lakes. The small yellow/white dots are cumulus clouds, note the zones of avoidance at some distance inland from the edge of the water. The cloud over Lake Huron is clearly fog as seen from it's sharp edge at the land/water boundary. Some wispy yellow cirrus clouds are visible in the western part of this scene. With this color combination yellow is cooler, the cirrus clouds are higher than the cumulus clouds. A view using single channels, channel 1, and channel 2 perhaps give a better look at the clouds. More details are visible in views of individual lakes: Lake Michigan (3 channel color composite), Lake Huron, Lake Erie, and Lake Ontario. Todd Sikora of Penn State/JHUAPL explains that what you see in this image is the cloud signature of lake breeze circulations around the Great Lakes. Air rises over the warm land in descrete convective elements whose tracers are the cumulus clouds. Once this air is no longer bouyant, it ceases to rise and diverges horizontally. Some of this diverging air flows over and descends towards the cool lakes. The vertical convergence of air near the lake surface results in a near-surface density current of cool lake air flowing outward from the lakes onto land (the lake breeze). Where the cooler lake-air meets the warm continental air, a lake breeze front forms. On the cool side of this front, stable boundary layer stratification suppresses the development of convective elements and, hence, the cumulus clouds. |
