Feb/07/2016
Crystals / Water phase change / Winter Activities

Frozen Water Vapor = Snow Crystals

Consider exploring the world of frozen water. This time of year, your child can discover fascinating things about ice and snow (snowflakes) – especially if you live where winter brings this delight right to your doorstep. If not, then maybe some creative fun with the refrigerator can work too.

Snow, specifically individual snowflakes, is geometric arrangements of tiny particles of ice. They are typically not single crystals but complex geometric arrangements of many ice crystals known as polycrystals.

Examine existing crystals or make some of your own. Enjoy the exciting patterns and appreciate nature’s beautiful and often perfect creations.
shutterstock_345544280

 
 

Questions

What do snow crystals look like?

 

Are all snow crystals the same shape?

 

Where can I find them?

 

How do they form?

 

What are icebergs all about?

 
 

Observe

As they fall from the sky, collect snowflakes or snow crystals outside on black paper or a dark colored mitten. Take a quick look before they melt. Really cold temperatures are best. Can you see the distinct patterns and shapes? A magnifying glass will help to see the distinct shape and features of these crystals.

 

 

If collecting your own snowflakes or snow crystals is too difficult because they melt quickly or you do not live in an area where this is possible, share with your child amazing photos of snow crystals. Here is a good site:

 

http://www.snowcrystals.com/photos/photos.html

 

Invite your child to find the language to describe what he is seeing. Write down descriptive sentences in a journal if your child seems interested. Suggest drawing these or making up one’s own snowflake patterns and designs. Fold a square piece of white paper in half and half again, then holding onto the common corner fold it once more into a “triangle” or wedge-shaped. Now cut patterns out of the edges keeping the common corner in the center. This is also a fun way to try and replicate a snowflake that was observed. Notice by doing this you will create a snowflake with 8 identical “arms” and perfect natural snow only has 6.

 

 

Each snow crystal is unique! Your child will not be able to find two that are alike. Absolutely amazing!

 

 

How many different types of snow crystals are there? At this point in time, an exact number has not been determined, but there are some common structures. The most common is the stellar dendrite. This is the iconic snowflake. If looking at a perfect stellar dendrite your child should notice the six point or six arm symmetry and hexagonal array of the ice crystals formed directly out of water vapor.

 

But not every snowflake fits this iconic shape. These are not common and most snowflakes are not perfectly symmetrical. The final shape depends on how the ice crystals fuse together and gather those water vapor molecules as they are hurtling through the clouds. Snow crystals may also be damaged as they fall to the earth or collide with other crystals, breaking off portions and destroying the symmetry.

 

Here is a description of the formation of snow crystals from:

 

http://www.snowcrystals.com/science/science.html

 

Why such complex, symmetrical shapes?
A stellar snow crystal begins with the formation of a small hexagonal plate, and branches sprout from the six corners when the crystal grows larger. As it tumbles through the clouds, the crystal experiences ever changing temperature and humidity, and each change makes the arms grow a bit differently.

 

https://www.youtube.com/watch?v=GlQVkZA5j-A

 

The exact shape of the final snow crystal is determined by the precise path it took through the clouds. But the six arms all took the same path, and so each experienced the same changes at the same times. Thus, the six arms grow in synchrony, yielding a complex, yet symmetrical shape. And since no two snow crystals follow the exact same path through the clouds as they fall, no two look exactly alike.

 

Other snow crystal shapes are listed in the sites referenced below. As you can see the final shape may depend on the temperature and moisture content in the air. When the temperature is low, there is less water vapor in the air and crystal growth is slower. Slow growth results in the less complex forms such as columns. When the temperatures are warmer (but still at or below freezing) and there is more water vapor, snow crystals form more rapidly and the result is a more complex and intricate shape.

 

http://www.snowcrystals.com/guide/guide.html.

 

And here:

 

http://www.snowcrystals.com/science/Snowflake%20Morphology2.jpg.

 

If it is snowing and you see puffy balls, these are not individual snow crystals although we may call these snowflakes. Instead, they are made of many snow crystals that have collided and are now stuck together and are falling as a single “flake.”

 

 

There are other forms of frozen precipitation or sleet, hail and freezing rain. These all result when liquid water meets freezing temperatures, but do not confuse these with snow crystals. Snowflakes are formed when water vapor freezes without first becoming a liquid. The other three forms of frozen precipitation start out as rain or the liquid form rather than vapor.

 

For more information about other Crystals see a recent post on this site.

 

http://guidingcuriosity.com/curious-crystals/

 

 
 

Compare and Contrast

When your child is outside capturing and observing snowflakes invite him to quickly sketch what he observes. Consider helping him to list the similarities and differences. Alternatively, look at a bunch of photos of individual snowflakes. What are the common features?

 

 
 

Experiment and Measure

If you live in an area that is covered with snow you can do a simple experiment by just observing it melt. Go outside and let your child collect a larger container full of snow to bring inside. Have six or eight identical smaller containers waiting inside. It helps if these are transparent, so observations are easier. If you don’t want to use glassware, then transparent plastic drinking cups are cheap, easy to get and reusable. Divide up the freshly collected snow into roughly identical amounts in each of these containers and then let your child place them in different locations around the house. Try to fill them with the same amounts to start – meaning don’t “pack the snow” more in some containers than others. Be sure to suggest the refrigerator and/or freezer for one or two samples. One could be under a lamp, one in the bathroom, the basement, etc., but let your child choose where. You could also suggest leaving one container outside as a “control”. Ask your child to predict or hypothesize what will happen. Make sure she has a journal to make notes. After some time has passed have her observe each container and write a description or draw a picture what she sees. It helps to have a results table prepared ahead of time with a list of the places the containers have been placed. Be sure to check the containers quickly so roughly the same time has passed for each one for a given observation. It’s fun running around the house playing scientist. Do this several times and then discuss the results. What conclusions can your child draw?

 

As an add-on, you can take the temperature of the snow outside, the snow inside in those cups and the temperature of the water after the snow has melted.

 

 

Grow your own ice crystals. Crystals are not alive, so the term “grow” refers to creating the right conditions and observing chemical reactions.

 

Parental supervision/assistance is needed to do this simple experiment at home because of the dry-ice involved; however, the hands-on nature of this activity with your child provides an easy window into experiencing the fascinating world of science.

 

https://www.youtube.com/watch?v=ExvA5V6CUq0

 

Icebergs are frequently in the news.  Think of the Titanic…but these days we see icebergs as reminders of shrinking glaciers. Icebergs consist of freshwater from compacted snow. Here is a fun activity to explore an “iceberg” up close and personal.

First, get a one gallon, sealable plastic baggie, plastic garbage bag or a larger Tupperware container to fill with water to make into your “iceberg”. Do this with your child and so she has some “skin in the game” and allow her to add a little blue food coloring, glitter or some small objects before freezing this solid in the freezer (or outside if you live in the right place).

 

 

After a day or two when it is frozen and your child has enough time, release the iceberg into the sink or a washtub that you have filled with water. Make sure the water is deep enough so your iceberg doesn’t rest on the bottom. Does it float or sink? How much ice is above the water as opposed to beneath it? If your iceberg is in the sink allow her to play with the water faucet or “sprayer” to see what impacts melting. Discuss where does the melted ice go? What happens? All of this can lead to a broader discussion of the melting of the polar ice caps or retreat of glaciers and things that are going on in the real world. Look up where the polar ice caps are on a map (the top and the bottom of the globe!).

 

 

Here is some information about glaciers to entice and further the conversation.

 

About glaciers: https://nsidc.org/cryosphere/glaciers

 

 
 

Elaborate

Dress warmly and head outside to play. Instead of building a snowman, consider sculpting animals such as a snake, shark fin, or penguin. These should be relatively easy for a child to imagine and carry out the construction of.

 

 

On a very cold day, blow bubbles and watch them freeze.

 

Paint the snow with food colors.

 

Make snow ice cream. Pack some clean snow in a cup and pour maple syrup on top. Or mix a solution of sugar, a drop of two of vanilla or peppermint extract, and some milk or cream. Pour this over your packed clean snow for a yummy experience. You can pour a little or a lot, depending on the consistency your child prefers.

 

 

Build a snow fort!

 

 

Vocabulary

 

Sixfold symmetry

 

Dendrite

 

Freezing/Melting

 

Crystals

 

Vapor

 

Icebergs

 

Glaciers

 

 

Photos courtesy of Shutterstock.

 

Thanks, Tony!

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