Snow crystals are created when water molecules collect and freeze onto a dust particle, or bacteria or some other solid material inside of a cloud, below or at freezing point.
As free water molecules adhere to the small snow crystal, a hexagonal prism crystalline lattice evolves. Snow crystals may be as small as microscopic specks, or may grow to be a few millimeter in diameter.
Snow crystals vary in pattern and type, under different conditions of moisture and temperature. They can generally be classified into six basic patterns and many
different types. Listed below are the types and their descriptions:
- Stars
- Dendrites
- Columns
- Plates
- Column capped with plates
- Needles
Stars, the most common crystals, form near -15 degrees C. They may grow up to be
8” by 12” in size (largest found in Bratsk, Siberia, in 1971).
Dendrites are like stars but they branch and grow in more than one plane. They form
between -20 to -25 degrees C, and require high atmospheric moisture.
Columns grow in dry air, between the temperatures -15 to -25 degrees C. They grow to look like long columns.
Plates grow in dry conditions, between the temperatures -10 to -20 degrees C. They are like stars but without the arms.
Column capped with plates, form in mixed conditions over varying temperature and moisture.
Needles are formed at higher temperatures, between -5 to -10 degrees C.
Snow crystals combine together to make snowflakes to make snow.
Follow the sources to see some eye candy.
SOURCES
www.teachervision.com. (Online). http://www.teachervision.com/lesson-plans/lesson-3827.html. Accessed December 30, 2001.
Libbrecht, Kenneth G. (Online). http://www.its.caltech.edu/~atomic/snowcrystals/faqs/faqs.htm. Accessed December 30, 2001.
Libbrecht, Kenneth G. (Online). http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm. Accessed December 30, 2001.
Unknown. (Online). http://www.anri.barc.usda.gov/emusnow/color/color.htm. Accessed December 30, 2001. (only photos)