Sebago Lake appears as a dot on the image. Other large lakes, such as Lake Winnipesaukee in New Hampshire and Moosehead Lake in Maine are also visible. During the day, this data stream consists of one visible and one infrared image. At night, both channels are infrared. Imagery in both the visible and Infrared formats is transmitted simultaneously.
Students are familiar with the visible image because it is like a conventional camera.
Understanding what the infrared imagery represents is sometimes harder to grasp. Various land and water bod ies absorb heat differentially, so they reflect different levels of heat energy. The Gulf Stream is an excellent example. On an infrared image, the warmer temperatures of the Gulf Stream are clearly delineated as the darker portions of the image, while the cooler temperatures of the surrounding Atlantic are lighter in color. HRPT imagery has a resolution of 1.1 km.