Snow

So You Want to Do a Project about Snow!

Purpose

To determine the amount of air in snow.

Materials

• masking tape
• marker
• four 10-ounce (300-mL) transparent plastic cups
• snow
• metric measuring cup

Procedure

1. Use the tape and marker to label the cups "A," "B," "C," and "D."
2. Scoop each cup across the surface of clean snow to fill it. Use your hand to level the snow in each cup, but take care not to pack the snow in the cups. Use fresh snow if possible.
3. Allow the cups to sit at room temperature until the snow melts.
4. Pour the water from cup A into the measuring cup. Measure the water in milliliters and record the volume of water in the melted snow in an Air Volume Data table like the one shown.
5. Repeat step 4 with cups B, C, and D.
6. Fill one of the cups to overflowing with water. Pour the water into the measuring cup. Read the measurement and record it in the data table as the volume of the cup. (The volume of the cup is equal to the total volume of snow and air that the cup can hold.)
7. Determine the volume of air in the snow by subtracting the volume of water in the melted snow from the volume of the cup. For example, if the volume of the cup is 300 mL and the volume of water in the melted snow is 80 mL, then:
   300 mL - 80 mL = 220 mL

The volume of air would be 220 mL.

Results

The cups full of snow melt, producing water that does not fill the cup. The amount of water will vary.

Why?

The more air that is mixed with the snow, the smaller the volume of water in the melted snow. When the snow melts, the air in the mixture is released.

Snow is composed of small crystals of frozen water called snow crystals. These crystals are formed when water vapor in the air condenses on a dust particle, forming a tiny water droplet. The water droplet is lifted high above the ground by rising air, where the temperature is below freezing, and the droplet freezes into a tiny ice crystal. If the temperature is around 5°F (-15°C) and there is plenty of water vapor, the ice crystal grows six branches and becomes a snow crystal. Snow crystals grow as water vapor freezes on them. The process by which a vapor changes directly to a solid without becoming a liquid is called sublimation. The shapes of the crystals vary, but they are all basically hexagonal (six-sided). The exact shape depends mainly on temperature.

Snowflakes are formed by the accretion (an increase in size by joining together) of snow crystals. As snow crystals fall through the clouds, they collide with other snow crystals, forming snowflakes. The size of a snowflake depends on the number of crystals in it. As the moisture content of the air increases, more snow crystals form, so more of them will collide and form larger crystals. A 2-inch (5-cm) snowflake is considered very large. An 8-inch (20-cm) snowflake measured in Bratsk, Siberia, in 1971 was a megasnowflake.

For Further Investigation

As snow piles up, does it push on lower layers and squeeze out the air? A project question might be, How does the depth of snow affect its air content?

Clues for Your Investigation

Repeat the investigation with snow samples from different depths. Do this by removing a layer of snow with a shovel and scooping out the snow beneath. Take four or more samples from each different depth.

References and Project Books

•  Ardley, Neil. The Science Book of Weather. San Diego: Harcourt Brace Jovanovich, 1992.
• Christian, Spencer. Can It Really Rain Frogs? New York: Wiley, 1997.
• Kahl, Jonathan D. National Audubon Society First Field Guide: Weather. New York: Scholastic, 1998.
• Reader's Digest. Why in the World? Pleasantville, N.Y: Reader's Digest, 1994.
• Suzuki, David. Looking at Weather. New York: Wiley, 1991.
• VanCleave, Janice. Janice VanCleave's A+ Projects in Earth Science. New York: Wiley, 1999.
• Janice VanCleave's Earth Science/or Every Kid.New York: Wiley, 1991.
• Janice VanCleave's Weather. New York: Wiley, 1995. 

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