All About Snow

Photograph of snow crystals taken by a scanning electron microscope Once snow crystals form in the atmosphere, they grow by absorbing surrounding water droplets. The snowflakes we end up seeing on the ground are an accumulation of these ice crystals. This magnified image of snow crystals was captured by a low-temperature scanning electron microscope (SEM). The pseudo colors commonly found in SEM images are computer generated, and in this case highlight the different flake formations. Photograph courtesy Agricultural Research Service, United States Department of Agriculture

As winter approaches the Northern Hemisphere, millions of people unpack thick coats, hats, scarves, and gloves in anticipation, and sometimes dread, of the oncoming snowy weather. Snow affects many of us in some way. People must live and work in it, and cities must find ways to remove it. Animals and plants adapt to survive in snowy regions. Snowy weather can cause dangerous conditions, or create seasonal opportunities to get out and play. NSIDC’s recently updated educational Web site, All About Snow, can help satisfy your curiosity about snow. The site covers everything from snowflakes to snowstorms, explaining the various types of snow, both in the air and on the ground. Find out the difference between a flurry and a blizzard, how snow forms penitentes and rollers, or why snow looks white, blue, or sometimes pink or red.  Learn about how people and animals cope with snow, and even use it to their advantage. The expanded All About Snow also incorporates formerly separate educational pages from NSIDC’s cryosphere section, “Avalanche awareness” and “Have snow shovel, will travel.” Snow and the globe

Photograph of a snow avalanche Avalanches can be caused by a variety of factors, including terrain, slope steepness, weather, temperature, and snowpack conditions. Photograph copyright Richard Armstrong, NSIDC

Many people are only interested how snow might affect the weekend’s ski reports or the morning’s commute. But snow plays a much bigger role in Earth’s climate. So scientists also try to see how snow fits into the global picture: how much snow covers the globe each winter, and how long does it last? Each year, snow covers almost 18 million square miles of Earth’s surface, with 98 percent falling during the Northern Hemisphere winter. Because it is such a large component of the cryosphere, snow influences the Earth’s energy balance, regulating heat exchange between Earth’s surface and the atmosphere. Likewise, as climate shifts and regions warm, changes in the amount of snowfall and the extent of snow cover produce ripple effects throughout entire ecosystems. Snow that falls later in autumn and melts sooner in spring can extend growing seasons, or cause temperate plant species to creep northward into new territory. In turn, animals accustomed to snowy environments may increasingly find themselves drier and warmer for longer periods each year. To find out more, explore the updated and expanded All About Snow site. Find out why snow matters to people, plants, and animals all over the world, or browse the list of resources about snow, blizzards, avalanches, and other related topics. Visit All About Snow in the Education Center, or go to the Web site directly at