2. This assignment has been developed to instruct youon the use
of sound within a PowerPoint presentation.Therefore, narrating a
report written by someone elsedoes not give you the right to take
credit for itscontent. Instructions: Choose your weather topic Type
the report into a PowerPoint presentation Select the slide you wish
to record Click on the slide show tab and begin recording your
reading Be sure to check your timing and your work before
submitting to my wiki Add at least two pictures or clip art to your
presentation Comment on other classmates presentations Remember to
only add comments or suggestions that are constructive and ethical
in nature
3. How snowflakes are formedA report by Sam MontanaNarrated by
Kay Cremeans
4. Precipitation comes in many forms such as rain, sleet,hail
and snow. A snowflake starts out as a dustparticle. Then water
vapor starts to condense ontothe dust particle and if the
temperature is coldenough it freezes. Most naturally occurring ice
isshaped in a hexagonal structure. The snowflakebecomes more and
more formed because watermolecules have an attraction for each
other and wateris more stable in the form of ice. The water
moleculeis even more stable in the form of ice when arrangedin
hexagonal layers, and that gives the snowflake a6-sided symmetry.
As more and more water vaporcondenses onto this ice crystal, the
snowflake grows.
5. Several factors influence the shape of any onesnowflake, the
temperature, humidity and the aircurrents. If there are a lot of
dust and dirtparticles mixed in during this freezing process,
theshape of the snowflake is affected. As these icecrystals move up
and down in the cloud with theupdrafts and downdrafts they continue
to formand be shaped. Finally the snowflake is heavyenough to
escape the clouds updrafts and falls tothe ground.Falling to the
ground can also alter its shape. Ifthe snowflake spins it will
probably keep itssymmetrical shape. If they arent spinning whenthey
hit the ground they will lose their shape andbe lumpy.
6. Common snowflake shapesThe shape of the ice crystals that
form the snowflake isdependent on temperature. Here is a list of
their shapes andthe temperature that they formed in.25 32 F: Thin
6-sided hexagonal crystals, formed in the highclouds.21 25 F:
Needles or flat-sided crystals are formed in themiddle height
clouds.14 21 F: Hollow columns10 14 F: Sector plates, which are
hexagons withindentations.3 10 F: Dendrites, lacy hexagonal
shapes.Snowflakes are composed of many ice crystals that affect
theirshapes. They might start out as a one shape and land asanother
shape. You will probably never see two snowflakes thatlook alike,
it is a constant though that in the formation of one,it is always
6-sided, or hexagonal.Highly magnified hexagonal dendrite
snowflake
7. Why is snow white?Water is clear, so why is snow white.
Theanswer has to do with the fact thatsnowflakes have so many
light-reflectingsurfaces that they scatter the light into all ofits
colors, so snow appears white. It has todo with how the brain
perceives the lightinto the color.
8. There is another form of snow that somepeople have never
heard of or seen, it is calledgraupel, also referred to as snow
pellets. Somedescribe it as soft fuzzy hail. It starts out as
asnowflake and then combine with super cooledwater droplets frozen
together. These are smallpellets, not large like hail might be and
soft.
9. A side note about updrafts and downdraftsA snowflake can go
up and down in a cloudgathering more crystals that form its shape
until itgets heavy enough to fall to the ground. You canactually
see this updraft and downdraft actionyourself when it hails. The
next time it hails and ifthe hail is big enough, look for ones that
havebroken in half on the ground. You can see ringsinside the
hailstone. Each ring represents a trip upand down in the cloud. The
hailstone rises andgathers another layer of ice, then it falls in
thedowndraft and melts a little bit, rises up again andrefreezes
picking up another layer of ice until it getsheavy enough to fall
to earth. To learn about hail,you can read All About Hailstorms and
How HailForms.
10. Once you have reviewed the previousreport, you are to
search the internet for asimilar story and develop a
narrativepresentation.Once you are finished with yourpresentation
submit it to my wiki for reviewby your
classmates.http://student-assistance.wikispaces.comPlace your
finished assignment andcomments on the PowerPointnarrations
page
11. ReferencesMontana, Sam (2008). How snowflakes are formed.
Retrieved March 26, 2012
fromhttp://weather-meteorology.knoji.com/how-snowflakes-are-formed/
