SNOW SNOW CRYSTALSCRYSTALS

AMBER GANNONAMBER GANNONNOVEMBER 1, 2001NOVEMBER 1, 2001

PATTERNS 1/ DR. PATTERNS 1/ DR. CALDWELLCALDWELL

COMMOM COMMOM CHARACTERISTICSCHARACTERISTICS

Five different Five different shapes depending shapes depending on temperatureon temperature

Six folded Six folded symmetrysymmetry

No two alikeNo two alike Many different Many different

classificationsclassifications Intricate structuresIntricate structures

BASIC SHAPES OF CRYSTALS BASIC SHAPES OF CRYSTALS - THIN PLATES- THIN PLATES

Form at highest Form at highest temperatures (32 temperatures (32 to 25 F)to 25 F)

Considered “wet Considered “wet snow”snow”

Often combined Often combined with other shapeswith other shapes

Formed in Formed in transition from transition from rain to snowrain to snow

BASIC SHAPES OF CRYSTALS BASIC SHAPES OF CRYSTALS - NEEDLES- NEEDLES

Form at Form at temperatures of temperatures of 25 to 21 F25 to 21 F

Long and slender Long and slender six sided figuressix sided figures

Resemble Resemble squished thin squished thin plates mixed with plates mixed with hollow columnshollow columns

BASIC SHAPES OF CRYSTALS BASIC SHAPES OF CRYSTALS - HOLLOW COLUMNS- HOLLOW COLUMNS

Form at Form at temperatures of 21 temperatures of 21 to 14 Fto 14 F

Hollow throughout Hollow throughout the centerthe center

Instability in growth Instability in growth makes shape hollowmakes shape hollow

Some smaller Some smaller crystals are solid crystals are solid throughoutthroughout

BASIC SHAPES OF CRYSTALS BASIC SHAPES OF CRYSTALS - SECTOR PLATES- SECTOR PLATES

Form at Form at temperatures of 14 temperatures of 14 to 10 Fto 10 F

Generally small Generally small and very thickand very thick

Super saturatedSuper saturated Exhibit double Exhibit double

plate structureplate structure Completely solid Completely solid

shapeshape

BASIC SHAPES OF CRYSTALS BASIC SHAPES OF CRYSTALS - DENDRITES- DENDRITES

Form at Form at temperatures of 10 temperatures of 10 to 3 Fto 3 F

Most studied shapeMost studied shape Related to geometryRelated to geometry Highly Highly

supersaturatedsupersaturated Most commonly Most commonly

portrayed but not portrayed but not seenseen

DENDRITES CNTD.DENDRITES CNTD. Combines six folded symmetry and Combines six folded symmetry and

a branched patterna branched pattern Considered to have striking beautyConsidered to have striking beauty Grow large enough to be viewed Grow large enough to be viewed

without magnificationwithout magnification Formed in very complex and Formed in very complex and

variable conditionsvariable conditions Uncountable unique patternsUncountable unique patterns

SIX FOLDED SYMMETRYSIX FOLDED SYMMETRY Results from the Results from the

arrangement of arrangement of water molecules water molecules within the crystalwithin the crystal

Uniform Uniform throughout entire throughout entire structurestructure

Layered Layered hexagonal shapehexagonal shape

Has a two facesHas a two faces

BRANCHED PATTERNBRANCHED PATTERN Involves water Involves water

molecules in the molecules in the air and how they air and how they move around move around the crystalthe crystal

Many crystals Many crystals lack the patternlack the pattern

More common in More common in larger crystalslarger crystals

COMMON FACTS ABOUT COMMON FACTS ABOUT SNOW CRYSTALSSNOW CRYSTALS

Snowflakes are bunched together Snowflakes are bunched together snow crystals.snow crystals.

Dendrites are the least common Dendrites are the least common snow crystals.snow crystals.

It can be too cold to produce snow.It can be too cold to produce snow. No two crystals are exactly alike, No two crystals are exactly alike,

but many are similar.but many are similar.

WORKS CITEDWORKS CITED Bennett, Kathy. “What is the meaning of the phrase, “It is too Bennett, Kathy. “What is the meaning of the phrase, “It is too

cold to snow”? Doesn’t it have to be cold for it to snow?”. cold to snow”? Doesn’t it have to be cold for it to snow?”. Scientific AmericanScientific American. 9/19/01. . 9/19/01. <http;//www.sciam.com/askexpert/environment15.html>.<http;//www.sciam.com/askexpert/environment15.html>.

““Basic Shapes of Snow Crystals”. USA Today. 9/19/01.Basic Shapes of Snow Crystals”. USA Today. 9/19/01. Battersby, Stephen. “Designer Snowflakes.” Battersby, Stephen. “Designer Snowflakes.” New ScientistNew Scientist. .

V 168. December 2000. V 168. December 2000. Chan, Mark. “Why do snowflakes crystallize into such Chan, Mark. “Why do snowflakes crystallize into such

intricate structures?”. intricate structures?”. Scientific AmericanScientific American. 9/19/01. . 9/19/01. <http://www.sciam.com/askexpert/environment23.html.<http://www.sciam.com/askexpert/environment23.html.

““Let it Snow, Let it Snow, Let it Snow.” Let it Snow, Let it Snow, Let it Snow.” Science NowScience Now. Volume . Volume 2, March 1995.2, March 1995.

““Snow Crystals”. 10/21/01. Website: Snow Crystals”. 10/21/01. Website: www.its.caltech.edu/~atomic/snowcrystals.html..

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