The
sunrise of each new day brings such wonder and awe. I awoke to a seascape of a
white crystalline substance coating everything in sight. Trees were transformed
into giant cotton candy looking cones. Fences were coated ever so carefully in
this white bliss. Jack Frost had paid a visit and left behind what we call hoar
frost. This is only one of a few frost formations that appear when conditions
are just right.
Figure 1: Hoar frost on trees retrieved from http://nz-landscapes.co.nz/photos/Hoar-Frost-Ophir.jpg
Frost
crystals grow from water vapor in the air, but unlike snow crystals that form high
in the clouds on suspended particles of dust, frost crystals form near the
ground. They grow on window panes, blades of grass, fences, tree branches, or
just about any other solid surface. Fog or saturated air contributes to frost
formation. Frost forms when an outside surface cools past the dew point. The
dew point is the point where the air gets so cold, the water vapor in the
atmosphere turns into liquid. This liquid freezes. If it gets cold enough,
little bits of ice, or frost, form. The ice is arranged in the form of ice
crystals. The warmth of the rising sun ends frost’s stunning displays.
Figure 2: Rime frost retrieved from http://photo.accuweather.com/photogallery/2011/12/500/a103bbe6a.jpg
The hoar frost, also called radiation frost, I saw this
morning is formed from layers of tiny ice crystals and is uniform on everything
it covers. It looks very feathery and it is the same kind of frost that forms
in refrigerators and freezers.
Video 1: Frost formations retrieved from http://youtu.be/IH42lN7y-pI
Ground
frost is the formation of ice on the ground. Grass, concrete, or other road
surfaces get covered in frost because their surfaces have a temperature below
the freezing point of water and they have cooled quicker than the surrounding
air. Ground frost can occur without air frost. Air frost is defined as having
air temperatures below the freezing point of water, but at a height of at least
one meter above ground.
Figure 3: Ground frost retrieved from http://beautyharmonylife.com/wp-content/uploads/2014/11/winter-lawn.png
Another kind of frost many of us have seen is window
frost. It forms when a glass window is exposed to cold air outside and moist
air inside. Cold climates with heated homes form this type of frost and it is
much more common on single paned glass. Elaborate patterns of frost grow on the
panes. Scratches, soap residue, or imperfections in the glass change the way
the crystals grow. They can resemble leaves, branches or feathers. Take a closer
look at the design of the next frost formation you notice on your on windows.,
Figure 4: Window frost retrieved from http://www.sciencephoto.com/image/103549/350wm/C0039323-Window_Frost-SPL.jpg
Rime is another type of frost. This frost is wind driven and
is from super cooled water droplets. Rime has the appearance of spikes. There
are frost formations called variously frost flowers, ice flowers, ice ribbons, or
frost swirls. We for will call them frost swirls for ease. The swirls form at
the base of plants from water that seeps from the plant stem. When the water
hits the cold air it freezes. As more water is extruded the swirls are created.
There are some phone apps
available at not cost to install on your own phone if you would like to follow
temperature and humidity; remember from above that frost forms when there is
the right elements of cold temperatures and water vapor in the air. The
following is an experiment we will be completing in class. I have included the instructions
if you would like to share it with your parents or siblings. See you in class.
Figure 5: Frost flower retrieved from http://i2.wp.com/blazepress.com/wp-content/uploads/2014/11/47ddca19e4f5eac84263c00a82b6b3d7_650x.jpg?resize=650%2C442
MAKE DEW & FROST
Taken
from http://www.weatherwizkids.com/experiments-frost.htm
MATERIALS:
- 2 tin cans without a lid (condensed soup cans work
well, but peel the labels off)
- rock salt or table salt
- crushed ice
PROCESS:
In one tin can put a mixture of
crushed ice about half full and about 4 tablespoons of salt.
Mix it well for about 30 seconds and
then let sit.
In the other can put only crushed
ice and cool tap water. Fill the can about half way full of ice and then put
just enough tap water in the can to cover the ice.
Note the frost forming on the
outside of the can with the ice and salt mixture. Compare this with the liquid
moisture on the outside of the can which contains ice only.
EXPLANATION:
Why does this happen? The salt wants
to absorb water to make a salt solution. To do that, the salt has to melt the
ice into water. The heat required to melt the ice comes from the ice itself. The
strange effect is caused by the chemical reaction between the salt and the ice.
Strange as it seems, melting the ice actually makes the mixture cooler. The
salt water mixture inside the can gets below freezing, so the moisture from the
air that collects on the outside of the can will freeze. This is why frost
forms!
On the other can, dew forms because
the mixture of the melting ice and water is just at freezing and the
temperature outside the can is warmer causing the dew to form.
Search
for these weather apps for your phone if you would like to learn more: Winter
Wakeup, Powder Alert, Road Trip Weather, plus many more.
If you would like to further discuss different frost phenomena or ask questions about frost formations comment below or follow me on twitter at @pwheeler20.
References:
Frost
Flowers. Retrieved February 19, 2015 from http://www.thedos.org/pics/frosts/index.html
National
Geographic Education. Frost. Retrieved February 19, 2015 from http://education.nationalgeographic.com/education/encyclopedia/frost/?ar_a=1
Snow Crystals.Com: Guide to Frost:
Different types of ice structures that
form on the ground. Retrieved February 19,
2015 from http://www.its.caltech.edu/~atomic/snowcrystals/frost/frost.htm
Types of
Frost. Retrieved February 19, 2015 from http://www.metoffice.gov.uk/learning/frost/types-of-frost
Weather
Whiz Kids. How to Make Dew and Frost. Retrieved February 19, 2015 from http://www.weatherwizkids.com/experiments-frost.htm
Figure references:
Figure 1: Hoar frost on trees retrieved from http://nz-landscapes.co.nz/photos/Hoar-Frost-Ophir.jpg
Figure 2: Rime frost retrieved from http://photo.accuweather.com/photogallery/2011/12/500/a103bbe6a.jpg
Video 1: Frost formations retrieved from http://youtu.be/IH42lN7y-pI
Figure 3: Ground frost retrieved from http://beautyharmonylife.com/wp-content/uploads/2014/11/winter-lawn.png
Figure 4: Window frost retrieved from http://www.sciencephoto.com/image/103549/350wm/C0039323-Window_Frost-SPL.jpg
Figure 5: Frost flower retrieved from http://i2.wp.com/blazepress.com/wp-content/uploads/2014/11/47ddca19e4f5eac84263c00a82b6b3d7_650x.jpg?resize=650%2C442
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