Dictionary Definition

Frozen precipitation in the form of white or translucent hexagonal ice crystals that fall in soft, white flakes.

Formation

Explanation

The first step in forming snow begins the same way as forming rain, with condensation forming in the clouds. Water vapor rises with the hot air and forms clouds. If the air temperature in a cloud is well below freezing, the water vapor may immediately change to solid. Most clouds that form precipitation have very small ice crystals in them, while others have water droplets or a mixture of the two. If the air inside a cloud is cold enough, the water vapor which is below the freezing point will condense on the dust in the clouds. The tiny liquid drops of water may hit these flakes and freeze to ice, making the snowflakes bigger. If there are rising air currents in the cloud, the droplets may be swept upward, bumping into ice crystals to create even bigger and heavier particles. Eventually the particles get so big that they fall to the ground in the form of snow.

Experiment #1: Snow Fall

What You'll Need:

• two sheets of paper

Directions:

1. Crumple one of the paper sheets into a ball.
2. Hold the flat sheet in one hand and the crumpled sheet in your other hand.
3. Drop both sheets at the same time.
4. Watch to see which sheet hits the floor first.

What's Happening?

Gravity pulls the same on both sheets of paper, but the upward force of air is different. Similarly, raindrops and snowflakes are both made of water, but they have different shapes. The raindrop, like the crumpled paper, takes up a small amount of space and falls quickly to the ground. The snowflake, like the flat sheet, takes up more space and therefore is pushed harder by the air to slow down the fall.

Shapes

Explanation

Just like fingerprints, no two snowflakes are ever the same. The way they are made, by bumping into each other, creates unique snowflakes each time. The conditions of temperature, humidity, and air turbulence are never exactly the same; therefore each snowflake turns out unique. The patterns of the snowflakes can be extremely beautiful. The next time you get snow, use the experiment below to see how unique and beautiful snowflakes can be. Each snowflake usually has six sides, and they are tiny, flat plates with delicate branches and needles extending from the center.

Experiment #2: Shapes

What You'll Need:

• dark-colored paper
• magnifying glass

Directions:

1. When it is snowing lightly, catch some flakes on the piece of paper.
2. Bring the paper inside and observe what the flakes look like with the naked eye.
3. Use the magnifying glass to look closer at the shapes.
4. Compare your two observations.

What's Happening?

As noted above in the explanation, there are many different shapes of snowflakes. Using a magnifying glass can help us look at the snowflakes closer. Without this aid, the snowflake isn't as interesting, but with the magnifying glass you can see the neat designs.

Hail

Hail is formed in large cumulonimbus storm clouds when the tiny ice crystals in the cloud are carried up and down by strong currents inside the cloud. Through this movement, water droplets freeze onto them to form layers of ice. The particles get bigger as more water freezes on to them, and eventually fall from their weight. Normally, hailstones are from 1/4 inch to 2 inches across, but can be bigger. When this precipitation falls, it is extremely damaging. Hail is known for breaking windows, ruining corps, and sometimes even hurting people or animals.

Measurement

When there is a storm, have you ever wondered how to measure how much is falling? Use the directions below to find how much snow is falling near you.

Experiment #3: Measurement

What You'll Need:

• coffee can
• ruler
• snow

Directions:

1. Mark inches on a coffee can starting at the bottom.
2. When a snowfall is forecast, place the can outside away from buildings and trees.
3. When it stops snowing, record the number of inches of snow in the can.
4. Let the snow melt and measure the amount of water again.

What's Happening?

This experiment gives you a lot of information. First, you can see how much snow falls where you live. Also, you can determine the ratio between snow and the resulting water if you try it several times. There is less water measured than snow because snow has lots of air trapped in its crystals that are freed when the snow melts. If the ratio of snow to water is consistent, you can determine how much water normally melts from the snow.