You might notice that winter forecasts of a foot or more snow are fairly common. This is very different from rain forecasts. Even in rainy areas, single rainstorms that top five inches are unusual. If the rainfall were as deep as the snowfall, regular flooding would be inevitable. This difference between the depth of snow and rainfall prompts questions as to whether these two are equivalent.
If you listen to ski reports or participate in winter sports, you are familiar with “wet snow” and “dry snow.” Since wet snow contains more water than dry snow, meteorologists say that wet snow is more dense than dry snow. Wet snow forms when the temperature in the lower troposphere is near the freezing temperature. Dry snow forms when the troposphere temperature is colder. The water content of snow is related to temperature because cold air can hold less water that warm air. The ratio of snow to water is roughly 10 to 1 or less if the snow is wet. This ratio increases to 11, 12 or even more inches of snow for every inch of water if the temperature is colder and the snow is dry.
The goal of these experiments is to learn about different types of precipitation, evaluate the density of snow and calculate the ratio of snow-to-liquid.
- Tall, narrow can (such as the one that Pringles potato chips come in)
- Internet access
- After a snow fall, find an area of snow that is representative of the total snow fall. Do not choose an area where the snow has drifted. The total snow fall should not be more than the height of the can.
- Drop the can over the ground with the open end of the can facing down. Make sure that the can is taller than the total snow fall. Immediately pick the can up and use your ruler to measure the depth of the snow.
- Bring the can into your house and place it in a room temperature area. As soon as the snow has melted, measure the depth of the water in the can.
- Calculate the ratio of the depth of the snow to the depth of the water.
- Go to http://weather.unisys.com/upper_air/skew/. Note the upper air temperature.
- Repeat steps 1 – 5 with several different snow storms. Does the ratio of snow-to-water vary? Does the variation relate to changes in upper air temperature?