The Earth Observing System (EOS) includes satellites, data archives, and scientific research programs dedicated to improving our understanding of the earth as an integrated system. These images of the western Great Lakes region were acquired by the MODIS instrument onboard Terra, the flagship EOS satellite. They show the cycle of the seasons over Lake Michigan, Lake Superior, and surrounding areas.
In February, most of Lake Superior is covered with ice. Its grayish-white color suggests there’s little or no snow on the ice. On Lake Michigan’s Green Bay, the ice appears to be mostly covered with snow.
By April, the remaining ice is limited to a few bays on Lake Superior. Snowmelt flows from streams and rivers into the lakes, causing sediment plumes that are visible along the southern shore of Lake Superior and in the western end of the lake. In southern Lake Michigan, sediment is stirred up by wave action and forms a long green-blue plume running along the south shore.
By early September, the region’s forests and agricultural fields are dark green. Tiny plants, known as phytoplankton, bloom in the warm waters of Lake Michigan and alter the chemical and optical properties of the lake, creating swirling pale-blue patterns when seen from space.
As October brings shorter days and cooler temperatures, the forests in the north begin to turn red and orange, while harvested fields in the south appear tan or light brown. On the date of this image, large algal blooms brought a vibrant green color to Lake Winnebago and parts of Green Bay.