The graphic that heads all the pages on this website is created from satellite data, of two different types. It depicts, as the geographically cognizant reader will undoubtedly have deduced from Nova Scotia- and Long Island-resembling shapes, a part of the western Atlantic Ocean – the part that is traversed by the Gulf Stream after separating from the coastline at Cape Hatteras. The colorful part of the image is a rendition of sea surface temperature (‘SST’), derived from measurements made by NOAA‘s Advanced Very High Resolution Radiometer (AVHRR). Although the colors have been chosen merely for their aesthetic virtues, they do depict warm water in the red-magenta and cold water in the blue range. The Gulf Stream itself flows along the red-blue boundary between the warm and cold water masses, where the temperature gradients are strongest.
The AVHRR image is overlain by a depiction of cloudiness derived from a different satellite product: infrared radiation measured by a Geostationary Operational Environmental Satellite (GOES), the type of satellites used by the United States’ National Weather Service. While GOES also images visible light reflected by the earth and its enveloping fluids, the particular AVHRR overflight I used appears to have happened during nighttime, when reflected visible light is, obviously, not available. Infrared radiation, on the other hand, is not reflected sunlight but emitted by matter itself at all times, with intensity depending on its temperature.
The data used were collected in the early AM hours on June 3rd, 2005.
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