Snow cover and land surface temperature influence each other. Snow influences how hot or cold the land feels to the touch, and it can chill the air that sits next to the surface. Land surface temperature influences whether or not snow remains on the ground or melts away. As air temperatures warm, snow begins to melt, and the exposed darker ground can cause a positive feedback to the melting process by absorbing more of the Sun's warmth.
Land surface temperature is a measurement of how hot the land is to the touch. It differs from air temperature (the temperature given in weather reports) because land heats and cools more quickly than air. This image depicts average monthly land surface temperature in degrees Celsius as measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. The warmest temperatures are pale yellow, while the coldest temperatures are dark blue. Moderate temperatures are depicted in shades of pink and purple. Regions where land surface temperature measurements were not possible are gray.
The snow cover map shows the fraction of an area covered by snow on a monthly basis. Measurements were made by the MODIS sensor on NASA’s Terra satellite. Gray indicates land areas with no snow, darkest blue represents minimal snow cover, and solid white indicates 100 percent snow cover. 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 the polar region.
The most obvious connection between land surface temperature and snow cover is the way they both change with the seasons. The second important influence on both snow cover and land surface temperature is elevation. Unlike other regions at the same latitude, the Tibetan Plateau sees both low surface temperatures and some degree of snow cover year round. To a lesser degree, the same is true of the Andes Mountains in South America. As snow retreats in many parts of the United States in the summertime, light snow cover lingers in the Rocky Mountains, along with cool land surface temperatures.
View, download, or analyze more of these data from NASA Earth Observations (NEO):
Land Surface Temperature
Snow Cover
