9781422272503

Snow, Snow, and More Snow! Many types of snow exist. Graupel is one form. When snowflakes fall through a cloud that contains supercooled water droplets, the snowflakes are already formed or forming and the water droplets freeze onto the snowflake to create lumpy balls of ice pellets. Hoarfrost describes the spiky frost sometimes seen on windows. Hoar means “ancient,” and the frost is named after an old man’s bushy beard. When water vapor instantly freezes on a cold surface, hoarfrost forms. The air moisture skips the liquid phase and transforms from vapor to solid, a chemical process called sublimation . Hoarfrost is usually seen on fence wires, plant stems, and tree branches. Needle ice is seen in an upright formation in wet areas when the soil temperature is warmer than the very cold air. Underground water is pulled up to the surface by capillary action, which then freezes and contributes to a growing needlelike ice column. Farmers and people who live in snowy conditions have developed many names to describe different forms of snow. Coarse, granular snow is called corn snow , and it forms by melting and refreezing. Lake-effect snow is produced when icy winds move across a body of warm lake water. This type of abundant, heavy snow is very common in the US Great Lakes region (Montague, New York, is located in this area). A polycrystal refers to several snowflakes that merge to form a large, massive snowflake. And what is snirt ? You guessed it—snow mixed with dirt. A snowdrift refers to snow on the ground that has blown to a greater height than the snowfall. A barchan is a snowdrift shaped like a horseshoe. Firn refers to snow that is more than a year old, and perennial snow has remained on the ground for more than a year. A ground blizzard has no new snowfall, but strong winds lift existing snow off the ground and reduce visibility. Rime refers to snowflakes that are coated with tiny frozen water droplets, smaller than graupel. Powder is what most

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The New Weather: Amazing Weather Facts