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What can snowstorms reveal about climate?

Snowstorms develop when warm, moist air collides with cold air. The warm, moist air mass and the cold air mass can each be 1,000 kilometers or more in diameter. Air masses moving north from the Gulf of Mexico and cold air masses moving south from the Arctic often collide to form snowstoms in the northeastern United States. In the Northwest U. S. warm, moist air from the Pacific Ocean cools when it is pushed upward by the mountains. The result is precipitation on the side of the mountains. These two explanations are oversimplifications. Many factors contribute to the formation of a storm, including direction of air movement, moisture content, and temperature of the colliding air masses. All of these affect the type and severity of the snowstorm.

Local weather patterns can be understood by studying snowstorms. In addition to the weather factors monitored in Weather Watch, the types of snowflakes that fall can be identified. The shape of a snowflake is determined by the moisture content in the cloud where the snowflake forms. Using radar and weather balloons, ground-based weather stations collect more sophisticated local data. Weather satellites and other NASA satellites that study snow and ice provide information about large air masses, weather conditions thousands of kilometers away, and the accumulation of snow over large areas.

Man sitting in snow and writing on a notepadFrom Students:
Temperature, moisture content, types of snowflakes and the amount of snowfall can tell a lot about a snowstorm and about local weather. Students make measurements and compare them with professional data.
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A weather station covered in snowFrom Weather Stations:
Professional ground-based weather stations, radar and weather balloons provide critical data about atmospheric conditions, moisture content of a storm system and snowfall. Large weather systems that affect many states can be monitored to understand local weather.
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EarthFrom Satellites:
NASA and weather satellites monitor atmospheric conditions from space. Large weather systems can be monitored and tracked with data from satellites. Snow accumulation over vast areas can be seen from space.
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While you wait for a snowstorm, use the activities in the From Students component to involve your students in identifying snowflake types and measuring snow accumulation.

Students should record basic weather data daily. Later in the year, they plot the data in a climagraph and compare their climagraphs with climagraphs from other locales.

Waiting for a snowstorm is also an excellent time to explore crystals and crystal structure with your students. Related Resources provides links to information about ice crystals, basic snowflake shapes, and snowflake classification systems. There are four systems used in the scientific community:
  1. The Basic Snowflake Forms is the least complex system. In this module, students use the Basic Snowflake Form with five size ranges -- a modification of the International system.
  2. The International Snowflake Classification System begins with ten basic forms and adds four additional characteristics and five size ranges that can describe modifications to each basic form.
  3. Nakaya's Snowflake Classification System subdivides falling snow into 41 categories.
  4. The Magono and Lee Snowflake Classification System is the most complex system with 80 different snowflake shapes.
Related Resources
Basic Snowflake Forms (PDF)
International Classification System (PDF)
Nakaya's Snowflake Classification System (PDF)
Magono and Lee Snowflake Classification System (PDF)
A Snowflake Primer (Web)  →