Kids Corner
​6th to 12th Grade

GWCC Snowflake Education

Introductory Video

Snowflake Dynamics

Snowflake Types:
​

Bullets
“Bullet snowflakes are a result of the nucleation (please refer to video above for details) of an ice grain, that yields multiple crystals. These crystals grow together in random orientations, and when those snow crystals grow into columns, they are known as bullet rosettes. The polycrystals which sometimes form will often break up, leaving isolated bullet shaped crystals.” -Dr. Ken Libbrecht, www.snowcrystals.com
Capped Columns
Capped column snowflakes are often a relatively uncommon brand of snowflake during a typical winter storm! However, if one goes to look for them during a given snowstorm, they are not all that hard to find. But, they are most easily identified under the power of a sufficiently strong microscope to accurately identify the associated capped column snowflake structure. Physically, capped columns look most like an “empty spool of thread, an empty fishing reel, or two wheels on an automobile” to the naked eye. These snowflakes are most likely to form when they fall through different layers of the lower and/or the middle atmosphere with varying vertical temperature profiles as they grow with passing time. The column portion of the growing snowflake grows most effectively when temperatures are around -6 degrees Celsius (21 degrees Fahrenheit), while the plates positioned at the end of each side of the column grow most efficiently at around -15 degrees Celsius (5 degrees Fahrenheit).
Columns
These crystals form similar to how needle-like crystals form. More often than not, these columns form with conical hollow regions at their ends. Commonly, column crystals are referred to as “hollow columns” due to this phenomenon where a hollow region forms. In order for these crystals to form, the in-cloud temperature where such snowflakes form must be around -21 degrees Celsius (-7 degrees Fahrenheit) where such snowflakes are forming above the surface of the Earth. These cold temperatures provide the right conditions for these crystals to form based on the fact that they will not form in warmer in-cloud temperature profiles.
Double Plates
These snowflakes look kind of like the classic dendrite snowflakes. For these types of snowflakes to form, the in-cloud temperatures must generally be between -15 degrees Celsius and -2 degrees Celsius (5 degrees Fahrenheit and 28 degrees Fahrenheit). Due to this wide range in temperature, these crystals are commonly found. “A double plate is basically a capped column with an especially short center column.  The plates are so close together that inevitably one grows out faster and shields the other from its source of water vapor. The result is one large plate connected to a much smaller one. These crystals are common -- many snowflakes that look like ordinary stellar plates are actually double plates if you look closely.” - Dr. Ken Libbrecht, www.snowcrystals.com
Fernlike Stellar Dendrites
These snowflakes, a part of the dendrite family, are the classic snowflakes that everyone knows and loves. Although hard to see because of their 5 millimeter size, these are the crystals that are usually present in winter or Christmas cards and, believe or not, are the largest snowflakes. “In spite of their relatively large size, these are singular ice crystals -- the water molecules are lined up from one end to the other. For these to form, the in-cloud temperatures have to be between roughly -15 degrees Celsius and -2 degrees Celsius (5 degrees Fahrenheit and 28 degrees Fahrenheit). Sometimes the branches of stellar crystals have so many side branches they look a bit like ferns, so we call them fernlike stellar dendrites.” - Dr. Ken Libbrecht, www.snowcrystals.com
Irregular Shapes
Like other crystals, the in-cloud temperature for this snowflake to form needs to generally be right around -2 degrees Celsius (28 degrees Fahrenheit). According to www.snowcrystals.com, “The most common snow crystals by far are irregular crystals.  These are small, usually clumped together, and show little of the symmetry seen in stellar or columnar crystals.” - Dr. Ken Libbrecht, www.snowcrystals.com
Needles
The temperatures needed for this snowflake to form are generally between -5 degrees Celsius (23 degrees Fahrenheit). These crystals are narrow and slender columns. According to www.snowcrystals.com, “One of the amazing things about these snow crystals is that their growth changes from thin, flat plates to long, slender needles when the temperature changes by just a few degrees.” When temperatures are a few degrees warmer they tend to form as a normal column snowflake, but when temperatures drop, they tend to become slim and narrow. - Dr. Ken Libbrecht, www.snowcrystals.com
Radiating Dendrites
6 to 12: For these snowflakes to form, in-cloud temperatures outside need to be between roughly -15 degrees Celsius and -6 degrees Celsius (5 degrees Fahrenheit and 21 degrees Fahrenheit). Radiating dendrites, also known as spatial dendrites, form when pieces of a polycrystal grow out into dendrites. These are very common snowflakes and one of the most recognizable crystals out there. How these crystals form from the beginning is what differentiates these crystals from other dendritic snowflakes.  - Dr. Ken Libbrecht, www.snowcrystals.com
Rimed Crystals
The best conditions for these crystals to form are temperatures in the -15 degrees Celsius and the -6 degrees Celsius (5 degrees Fahrenheit to  21 degrees Fahrenheit) range. According to Dr. Ken Libbrecht at www.snowcrystals.com, “clouds are made of countless water droplets, and sometimes these droplets collide with and stick to snow crystals. The frozen droplets are called rime.  All the different types of snow crystals can be found decorated with rime. When the coverage is especially heavy, so that the assembly looks like a tiny snowball, the result is called graupel.”
Sectored Plates
From Dr. Ken Libbrecht, “Stellar plates often show distinctive ridges that point to the corners between adjacent prism facets.  When these ridges are especially prominent, the crystals are called sectored plates.” A good way to explain this type of snowflake is to think of a hexagonal pie. Sectored plates are divided into six equal pieces.  More complex specimens show prominent ridges on broad, flat branches. In order for these snowflakes to form, in-cloud temperatures need to roughly be around -18 degrees Celsius (1 degrees Fahrenheit).  - Dr. Ken Libbrecht, www.snowcrystals.com
Simple Prisms
In order for these snowflakes to form, in-cloud temperatures need to be around -7 degrees Celsius (20 degrees Fahrenheit). If conditions are right, these snowflakes will fall with hollow columns, although they form at different water saturation levels. In terms of shape, hexagonal prisms are the most basic geometric snow crystal. These crystals often look like wooden pencils in terms of geometric shape, depending on how fast the crystals grow. These crystals are often captured as prisms since they are rarely captured perfectly flat in nature. Also, these crystals are usually too small to be seen with the naked eye.
“This video shows a plate-like crystal growing atop an "electric" ice needle at -15 C (See Electric Needles for more about how these are made.) The center part of the plate is nearly flat, so it is mostly transparent, like a clear sheet of glass. The edges of the plate are more complex. Even with this relatively simple ice crystal, there is quite a bit going on! 

If you look carefully in the second half of the video, you can see several concentric circular layers which gradually grow inward toward the center of the growing snowflake by way of the accumulation of clear ice.” - Dr. Ken Libbrecht, www.snowcrystals.com
Split Plates and Stars
For these snowflakes to form, in-cloud temperatures must be around -2 degrees Celsius (28 degrees Fahrenheit). According to Dr. Ken Libbrecht at www.snowcrystals.com, “these are forms of double plates, except that part of one plate grows large along with part of the other plate.” There are a total of eight different ways for the a split star to attach and form. All of the eight different methods involve which plate is on top of each other. These crystals are connected with a short center axle. Although common, these crystals often go unnoticed. Also, once one of these crystals are caught, it will take some time to see how these two distinct pieces fit together.
Stellar Plates
These snowflakes are commonly found in nearly all snowfall events which occur around the world during a given calendar year. Alike other plates, the in-cloud temperatures (in order for these to form) must range from approximately -15 degrees Celsius and -2 degrees Celsius (5 degrees Fahrenheit and 28 degrees Fahrenheit). More descriptively, these snowflakes are thin, plate-like crystals with six broad arms that form in a star-like shape, like the picture attached above. Although these look like stellar dendrites, these crystals are actually plates. Nonetheless, these snowflakes present a decorated, elaborate and amazingly symmetrical crystal.
Stellar Dendrites
“Dendritic means "tree-like", so stellar dendrites are plate-like snow crystals that have branches and side branches.  These are fairly large crystals, typically 2-4 mm in diameter and are easily seen with the naked eye.” - Dr. Ken Libbrecht, www.snowcrystals.com
“Dendrite snowflakes form in very low temperatures of -20 degrees Celsius to -25 degrees Celsius (-4 degrees Fahrenheit to -11.2 degrees Fahrenheit). The atmosphere contains abundant moisture to allow the intricate patterns in snowflakes to form. (Source Credit: ”https://www.metoffice.gov.uk/learning/precipitation/snow/snowflake)
Triangular Crystals
When the temperatures are near -2 degrees Celsius (28 degrees Fahrenheit), plates sometimes grow as truncated triangles. “If the corners of the plates sprout arms, the result is an odd version of a stellar plate crystal. These crystals are relatively rare. Surprisingly, no one knows why snow crystals grow into these three-fold symmetrical shapes”, Dr. Ken Libbrecht, www.snowcrystals.com. Although the overall layout of this snowflake looks different as compared to six-sided crystals, the molecular structure is often times very close to that of other snowflake types.
Twelve-Branched Snowflakes
In order for these snowflakes to form, two 6-sided snowflakes must collide and stick together. When the two collide, they create a 12-sided snowflake. These crystals are quite rare due to the environmental conditions that need to be met in order for them to form. From Dr. Ken Libbrecht, www.snowcrystals.com, “Sometimes capped columns form with a twist, a 30-degree twist to be specific. The two end-plates are both six-branched crystals, but one is rotated 30 degrees relative to the other.  This is a form of crystal twinning, in which two crystals grow joined in a specific orientation with respect to one another.”
Dr. Ken Libbrecht’s Book Sales Links
The Snowflake: Winter’s Frozen Artistry
https://www.amazon.com/gp/product/0760348472/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0760348472&linkCode=as2&tag=snowcrystals&linkId=PPWDEPEVYMWHSXLJ

The Secret Life of a Snowflake: An Up-Close Look at the Art and Science of Snowflakes
https://www.amazon.com/Secret-Life-Snowflake-Up-Close-Snowflakes/dp/0760336768/ref=sr_1_1?s=books&ie=UTF8&qid=1435006868&sr=1-1&pebp=1435006875268&perid=0DGBY8E4TTCXNZJQ07X0

The Art of the Snowflake: A Photographic Album
https://www.amazon.com/gp/product/076034700X/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=076034700X&linkCode=as2&tag=snowcrystals&linkId=LXHXL2TKB7TSPSUP

Ken Libbrecht’s Field Guide to Snowflakes
https://www.amazon.com/gp/product/0760326452/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0760326452&linkCode=as2&tag=snowcrystals&linkId=PDCQXR5NPYEHZEEB

Snowflakes
https://www.amazon.com/gp/product/0760334986/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0760334986&linkCode=as2&tag=snowcrystals&linkId=OKCRKZ2RFRPWNWDQ

The Little Book of Snowflakes
https://www.amazon.com/gp/product/0896586529/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0896586529&linkCode=as2&tag=snowcrystals&linkId=EGMQ2ZMJ7G252N2F