What makes it snow?

You probably know snow is made of ice crystals. Tiny crystals of frozen water stick together to make a flake. To make snow, you need:

Water Vapor
and
a way to make it very Cold.

Snow occurs differently than most people think--it is not from frozen raindrops! Moisture in the air freezes into crystals. Try this experiment to learn more about the moisture that causes snow:

Put a "typical" glass into a freezer. Look at the outside of the glass after a few hours. What is on the outside of the glass? How did it get there? Be sure to discuss this in class!

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The same thing happens in the atmosphere. Water vapor in air at temperatures below freezing can turn directly into ice crystals. The ice crystals form on miniature particles. That is the beginning of what we call snow! Sometimes the atmosphere becomes a big snow-making machine. This is what happened on December 18th.

Next, let's find out about how nature's "snow machine" works.