December 25, 2020 - Snow in Western United States

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   Snow in Western United States
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   When Americans celebrate the Christmas holiday each December 25, they
   are likely to have their homes decorated with traditional “Christmas
   colors” – red and green. If you ask why these colors represent what is,
   for many, a high holy day, you are likely to garner answers that span a
   gamut from secular to religious. Kids may say green is for the
   Christmas tree and red stands for the bright nose of Santa’s lead
   reindeer, Rudolph. Christians may explain that the color of evergreen
   trees represents eternal life and hope, as the trees endure the
   harshest winters and remain alive and that red represents the blood of
   Christ, whose birth is celebrated on this day. Others speculate that
   the colors of the season come from the holly tree, whose bright red
   berries and stunning green foliage stand out beautifully against snow –
   and was used by ancient Romans to decorate their homes for Saturnalia,
   a celebration held on the shortest days of the year, from December
   17-23. Then again, some historians claim that these colors became
   popular symbols of Christmas in America due to widespread advertising
   by the Coca-Cola company in the early 1930s. The ads highlighted the
   company’s green glass bottles of soda being held by a red-suited Santa
   and became, themselves, a symbol of an American Christmas.

   For scientists looking at false-color satellite imagery, however, reds
   and greens have nothing to do with Christmas, and everything to do with
   the reflectance of various features on Earth.

   The Moderate Resolution Imaging Spectroradiometer (MODIS) on board
   NASA’s Terra satellite acquired this false-color of image of snow
   across the Western United States on December 21, 2020. This image uses
   blue and shortwave infrared light (MODIS bands 3,6,7) to differentiate
   the various states of water—liquid, snow, ice, and clouds. In this
   combination of bands, vegetation appears green while deserts are
   blue-green. Ice or snow appears bright red, liquid water looks dark red
   to black, and clouds may appear white or, if they contain ice crystals,
   will appear reddish-orange or peach.

   This image is centered over the Great Basin in Nevada and Utah — an
   area made up of a series of depressions, flats, dry lakes, marshy salt
   pans and sinks, all scattered between ribbons of mountain ranges. Snow
   covers the northern section of the Great Basin, the Sierra Nevada
   mountains (west) and reaches east to Utah’s Great Salt Lake. Further
   south, mountainous deserts are colored blue-green. Peach-colored clouds
   in the north show the presence of ice while in the far southwest (lower
   left corner) a fog bank fills part of California’s Central Valley.
   Bright green vegetation lies between the fog and Sierra Nevada snow.

   Image Facts
   Satellite:  Terra
   Date Acquired: 12/21/2020
   Resolutions:  1km (196.7 KB),  500m (649.4 KB),  250m (1.9 MB)
   Bands Used: 3,6,7
   Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2020-12-25
 
