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These Moderate-resolution Imaging Spectroradiometer (MODIS) false-color
images show the total area in North America covered by snow (white
pixels) as compared to the 35-year average snowline (red line). Each
image represents an 8-day composite for the periods November 1-7, 8-18,
and 16-23, 2001. The light gray pixels show areas that were covered by
clouds for the entire 8-day period. The green pixels are land regions
without snow, blue pixels represent water, and dark gray shows where no
data were collected.