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| If
you are lucky you might be able to see some rare snowflakes, like these
on Sarah's scarf, without needing anything special. These near perfect
flakes were formed on a cold, (7° F), day with little wind. |
When cloud temperature is at freezing or below
and the clouds are moisture filled, snow crystals form. The ice crystals
form on dust particles as the water vapor condenses and partially melted
crystals cling together to form snowflakes. It is said that no two snowflakes
are the same, but they can be classified into types of crystals. All snow
crystals have six sides. The six-sided shape of the ice crystal is because
of the shape and bonding of the water molecules. Basically there are 6
different types of snow crystals: needles, columns, plates, columns capped
with plates, dendrites and stars. The type of crystals depends on the amount
of humidity and temperature present when they are forming. That's why when
it's very cold and snowing, the flakes are small, and when it's closer
to 32 F. the flakes are larger.
 Catch
Some Snowflakes
What you will need:
-
black velvet or black construction paper
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Magnifying Glass
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Snow
Since snowflakes melt so quickly you need to freeze your cloth or paper.
Have it ready frozen and ready to go for the next snowfall, and go outside
and let some snowflakes land on the dark surface. Quickly, before they
melt, examine the flakes with a magnifying glass. Many snowflakes are "broken"
and so you don't see the whole six-sided crystal, but with persistence
you'll see some beautiful examples.
Keep
Some Snowflakes
What you will need:
-
Piece of glass
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Hairspray (aerosol, NOT pump)
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Snow
You can have a permanent record of your caught snowflakes if you freeze
a piece of glass and the hairspray before the next snowfall. (Both may
be stored in the freezer until you need them.) When you're ready to collect
some snowflakes, spray your chilled glass with the chilled hairspray and
go outside and let some snowflakes settle on the glass. When you have enough
flakes bring the glass indoors and allow it to thaw at room temperature
for about 15 min. Now you have a permanent record of your snowflakes!
Note: I received this e-mail from a Finnish
meteorologist with this suggestion:
My boss (Pirkko Saarikivi)
made her PhD thesis on snowflakes and she used a new version of the hairspray
method: The Nobecutan method. Nobecutan (Trademark of Astra Meditec, Sweden)
is normally used to cover small injuries especially in head and animals.
I guess your drugstore has something similar.
Catch
Snowflakes to View Under a Microscope
Adapted from "Discovery On Ice" aired Feb.
21, 1995. Project contributed by Dr. Daniel Hutt.
What you will need:
-
box with a lid
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can of "Crystal Clear*" spray
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glass microscope slides
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microscope
 Crystal
Clear is a liquid plastic that can be sprayed on a surface and then
hardens to form a thin transparent film. Spray the Crystal Clear onto one
of the glass slides and let some snowflakes fall on it. The liquid plastic
will slowly creep up over the snowflakes and form a shell that replicates
every detail of each snowflake. After the plastic dries you will have a
permanent replica.
Before you begin, it is important to leave
the box with spray can and glass slides outdoors overnight so that everything
is exactly the same temperature as the falling snow. If the spray or slides
are just a little bit warm, the snowflakes will melt immediately when they
land on the plate and be lost.
Now, spray one of the slides with the plastic,
holding the slide out into the wind until you are ready to catch the snowflakes.
There. Now for the fun part - hold the slide out and in just a few seconds
you will have collected enough snowflakes. To keep the slide from getting
too much snow, put it back into the box.
Leave the wet slide in the box for several
hours until the plastic hardens. Later, when you bring the slide inside,
the snowflakes will melt but the plastic shell will remain, preserving
the shape of the snowflakes forever!
Once the replicas are dry you can carefully
examine the snowflakes under a microscope without worrying about melting
them. If you collect snowflakes you will notice that the beautiful
star shaped snowflakes are rather rare. Often you have needle or column
shaped crystals or irregular crystals. The shape of each snowflake depends
on the variations of temperature and humidity it experiences along its
path as it forms within the cloud and falls to the ground. Each snowflake
follows a unique path which is why all snowflakes are different from each
other.
More
Snow Science Activities
-
Make a snow gauge.
Take an old clear plastic soda pop bottle
and cut off the top half. Mark the outside in centimeters or inches with
a permanent laundry marker and place it outside in a place where it can
collect the falling snow.
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Measure how much melted snow it takes to make
water.
Collect some snow in a container and record
the level of snow on the container. Let the snow melt. how much water is
there? Are you surprised at the difference?
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Make your own glacier.
Fill a bowl with snow and bring it inside
to partially thaw, then add more snow on top. Keep doing this all winter
long. You will then have the "layers" of ice and snow like a glacier.
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Here is an activity sent in by Joyce from
Tahoe Ca.
Heat a 2 liter soda bottle in the microwave
- have an adult help you do this!
Put the lid on and put it outside in the
cold.
Suprise!
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