Terry’s Take: Now you snow it!

Posted on: 10:30 pm, November 14, 2013, by

Terry Swails Weather Blog

You either love it or hate it, there’s not much in between when it comes to snow. To me it’s one of the most beautiful and mysterious creations on earth. I’m always impressed how quickly and efficiently it can transform the landscape. In this article, some clarification on common terms associated with snow.

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Atmospheric conditions affect how snow crystals form and what happens to them as they fall to the ground. Snow may fall as symmetrical, six-sided snowflakes, or it may fall as larger clumps of flakes. Similarly, once snow is on the ground, the snowpack may assume different qualities depending on local temperature changes, whether winds blow the snow around, or how long the snow has been on the ground. For instance, a fresh snowfall may be loose and powdery, but snow that has been on the ground throughout the winter may have dense, crusted layers caused by melting and refreezing. Scientists and meteorologists have classified types of snowfall, snowpack, and snow formations.

TYPES OF SNOW CRYSTALS

  • Snowflakes are clusters of ice crystals that fall from a cloud.
  • Hoarfrost is the deposition of ice crystals on a surface when the temperature of the surface is lower than the frost point of the surrounding air. In this process, moisture goes directly from vapor to solid, skipping the liquid phase. Hoar frost is usually composed of interlocking ice crystals, and tends to form on objects of small diameter that are freely exposed to air, such as wires, poles, tree branches, plant stems, and leaf edges.
  • Graupel consists of snowflakes that become rounded, opaque pellets ranging from 2 to 5 millimeters (0.1 to 0.2 inches) in diameter. They form as ice crystals fall through supercooled cloud droplets, which are below freezing but remain a liquid. The cloud droplets then freeze to the crystals, forming a lumpy mass. Graupel is sometimes mistaken for hail, but tends to have a texture that is softer and more crumbly. Graupel is sometimes also called snow pellets.
  • Polycrystals are snowflakes composed of many individual ice crystals.
  • LAKE SHORE DRIVE AFTER THE GREAT GROUNDHOG DAY BLIZZARD OF 2011

    LAKE SHORE DRIVE AFTER THE GREAT GROUNDHOG DAY BLIZZARD OF 2011

  • TYPES OF SNOWFALL
    • A blizzard is a violent winter storm, lasting at least three hours, which combines subfreezing temperatures and very strong wind laden with blowing snow that reduces visibility to less than 0.40 kilometers (0.25 miles).
    • A snowstorm features large amounts of snowfall.
    • A snow flurry is snow that falls for short durations and with varying intensity; flurries usually produce little accumulation.
  • A snow squall is a brief, but intense snowfall that greatly reduces visibility and which is often accompanied by strong winds.
  • A snowburst is a very intense shower of snow, often of short duration, that greatly restricts visibility and produces periods of rapid snow accumulation.
  • Blowing snow describes airborne snow particles raised by the wind to moderate or great heights above the ground; the horizontal visibility at eye level is generally very poor.
  • Drifting snow is snow on the ground that is blown by the wind to a height of less than 1.5 to 2 meters (5 to 6.5 feet) above the surface.
  • BLIZZARD CONDITIONS WITH NEAR ZERO VISIBILITY

    BLIZZARD CONDITIONS WITH NEAR ZERO VISIBILITY