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We finally have snow in the Chicago area. The kids are happy; drivers not so much.

We know not to eat yellow snow but it may not be a good idea to catch even fresh flakes falling from the sky on your tongue. Snowflakes can pick up specks of dust and other pollution along their descent. Sometimes enough is accumulated that changes the color of the snow from white to grey or even pink.

Snowflakes require a cycle of nature beginning with the evaporation of water from rivers, lakes and oceans. When temperatures drop to 32 degrees Fahrenheit or below, the moisture forms into tiny ice crystals the size of dust. As the crystals fall, they connect with other crystals forming snowflakes. The more crystals that join together, the bigger the flake.

According to The National Snow and Ice Data Center, snow and ice usually appear white because visible light is white. Most natural materials absorb some sunlight, but snow reflects most of it creating that white appearance.

When snow appears blue, purple, or even pink it is a result of either light waves or foreign particles. Snow that looks blue is due to light waves scattered by the ice grains in the snow. When falling crystals gather algae, dust, and other foreign particles, the crystals pick up the color of the substance.

Here are a few other interesting facts about snow.

  • Snowflakes usually have six sides
  • Identical snowflakes are rare but possible
  • Most of the volume of a snow layer consists of air
  • Nearly every location in the United States has seen snowfall

©2013 Mary K. Doyle

(Information from The National Snow and Ice Data Center, http://nsidc.org/)

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