This week’s question was asked by Kaylee Holt, fifth grade, La Grange Elemementary School.
Teacher: Chelsey Juliot.
QUESTION: How is snow made?
ANSWER: Yes, it’s that time of year when we can expect snow. Snow occurs when water vapor in the upper atmosphere freezes before it can turn into water. It’s very cold up there, way below freezing. Crystals of ice condense on tiny bits of dust, smoke, and even oxygen molecules.
These crystals start out very small and grow with up to 100 to 200 crystals, with each crystal being different. No two snowflakes are identical, just as no two people have identical fingerprints. Two Wisconsin scientists beg to differ as they claim they found two identical snowflakes during a 1988 storm. The jury is out on this one.
Sleet is a bit different than snow. Sleet is tiny rain particles that freeze on their way down. Frost is a white layer of ice crystals on the ground. Water droplets, normally dew, freeze when the air temperature drops below freezing.
Anyone who has traveled down Interstate 90-94 has noticed snow being created at the Cascade Mountain ski resort near Portage. Machine-made snow is the exact same thing as natural snow that falls from the heavens. It is frozen water. Snow making machines provide a base, and hopefully Mother Nature will add more layers during the winter season. The artificial base can extend the season from late fall to early spring on many slopes.
They start with cold water that is piped to the trails. The water is met with compressed air. The compressed air is mixed with a little bit of water. The little bit of water added to the air stream provides the nucleus for the cold water to freeze onto, making snowflakes. The compressed air shatters the stream of water into minute particles and launches them into the atmosphere. From here, though, the process is similar to nature’s. The droplets of water freeze and fall to the ground. The only difference is that the water doesn’t have as much time to freeze before it hits the ground. It all happens in a matter of seconds. Forcing water and pressurized air through a snow gun or snow cannon is the basis of making snow.
Man-made snow tends to be icier than the fall-from-the-sky stuff. Skiers call the artificial snow “wet’ compared to the drier “powder” snow falling from the sky. In general, the more humid the air, the lower the temperatures must be to be for snow making. When humidity is extremely low, snow can be made at temperatures as high as 40 degrees, which is well above the normal 32 degrees freezing.
There is an old saying that “it is too cold to snow.” There is some truth to the legend. However, it can snow no matter how cold it is, providing there is enough moisture in the air. Yet we know it seldom snows if the temperature is 20 below zero Fahrenheit or colder.
The heaviest snowfall ever recorded in the United States was in 1923 in Silver Lake, Colorado. Over six feet of snow fell in a single day. The Mt. Baker ski area in Washington state had 1,140 inches (93 feet) of snow during the 1998-99 winter season.
Snow is quite cold, but snow can be an insulator. If we get an early snowfall of a few inches or more, the frost will not go down very far in the ground. The snowcover acts as an insulating blanket. The guys who dig graves in the winter and the city workers from the Public Works Department and Water and Sewer Department have a good handle on how far the frost goes down each winter. They know that a thick cover of snow prevents the ground from freezing to any great depth.
Igloos can be 100 degrees warmer inside than outside, warmed entirely by body heat. Fresh, compacted snow is 90-95 percent trapped air, making it a great insulator.
We look at snow and we say it’s white. Snow is actually clear and colorless. Very little light is absorbed by the crystal and the thousands of tiny surfaces reflect visible light uniformly for all wavelengths of light, all seven colors of the rainbow.
Yes, boys and girls, you can eat snow, so long as it is not yellow. Do go outside and make a snow angel. In 2011, Nova Scotia residents in 130 separate locations all plopped down to make snow angels. It’s a world record of 15,851. It is so much fun to try to catch snowflakes on your tongue. However, your tongue does not belong on a pump handle, or steel pipe, or metal railing.
Send questions and comments to: firstname.lastname@example.org.
Larry Scheckel is a retired Tomah High School physics teacher.
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