Snow is precipitation that forms when water
vapor freezes. Because snow is so reflective, it plays an important role
in regulating climate: it reflects incoming sunlight back into space,
cooling the planet. Snow also supports life. Melting of seasonal snow
(as well as glaciers) provides water for drinking and
irrigating crops in many parts of the world. Snowmelt moisturizes soil
and reduces the
risk of wildfire. Too much snow, however, can lead to springtime floods
when the snowpack melts.
These snow cover maps are made from observations collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra
satellite. Snow cover values range from medium blue (greater than 0
percent) to white (100 percent). Landmasses that do not sustain snow
cover and places where MODIS did not collect data are gray. Because
MODIS relies on visible light to assess snow cover, the sensor cannot
collect data over the highest latitudes of the Northern Hemisphere
during winter when no sunlight reaches those regions.
Snow and ice cover most of the Earth’s polar regions throughout the
year, but the coverage at lower latitudes depends on season and
elevation. High-altitude landscapes such as the Tibetan Plateau and the
Andes and Rocky Mountains maintain some amount of snow cover almost year
round. Land area is larger and snow cover is more variable in the
Northern Hemisphere than in the Southern Hemisphere.
- View, download, or analyze more of these data from NASA Earth Observations (NEO).
- ______________
- http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD10C1_M_SNOW
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