Have you ever wondered what a snowflake exactly is or how it is made and how do they achieve their unique shapes and patterns? Well wonder no more 
How Do Snowflakes Form?
A snowflake begins when a tiny dust or pollen particle comes into contact with water vapor high in Earth’s atmosphere. The water vapor coats the tiny particle and freezes into a tiny crystal of ice. This tiny crystal will be the “seed” from which a snowflake will grow. So basically, snowflakes are a particular form of water ice. Snowflakes form in clouds, which consist of water vapor. When the temperature is 32° F (0° C) or colder, water changes from its liquid form into ice. Several factors affect snowflake formation. Temperature, air currents, and humidity all influence shape and size. Dirt and dust particles can get mixed up in the water and affect crystal weight and durability. The dirt particles make the snowflake heavier, and can cause cracks and breaks in the crystal and make it easier to melt. Snowflake formation is a dynamic process. A snowflake may encounter many different environmental conditions, sometimes melting it, sometimes causing growth, always changing its structure.
So back to the basics. As the snowflake falls, it grows. The newly-formed ice crystal (snowflake) is heavier than the surrounding air and it begins falling. As it falls towards Earth through humid air more water vapor freezes onto the surface of the tiny crystal. This freezing process is very systematic. The water molecules of the vapor arrange themselves so that the hexagonal crystal structure of ice is repeated. The snowflake grows larger and larger as it falls, enlarging the hexagonal pattern.
Snowflakes Shapes
What Are the Common Snowflake Shapes
You very well may have seen lots of different types of snow flakes and I am guessing a lot of you are familiar with the six-sided hexagonal shapes. However, there are in fact lots of types of different shapes of snowflakes. As we discussed above, snowflakes can vary in their shapes due to the kind of conditions they have en-counted during their creation and even their seed. Lets not forget that snowflakes are very small especially at the very first point of the water crystallizing on the seed. Therefore any tiny variations in the seed can dramatically change the process of crystallization. Then the falling snowflake will have varying temperatures, humidity and winds that all have a slight and unique imprint on each snowflake.
The Common snowflake Shapes
Generally, six-sided hexagonal crystals are shaped in high clouds; needles or flat six-sided crystals are shaped in middle height clouds; and a wide variety of six-sided shapes are formed in low clouds. Colder temperatures produce snowflakes with sharper tips on the sides of the crystals and may lead to branching of the snowflake arms (dendrites). Snowflakes that grow under warmer conditions grow more slowly, resulting in smoother, less intricate shapes.
> 32-25° F – Thin hexagonal plates
> 25-21° F – Needles
> 21-14° F – Hollow columns
> 14-10° F – Sector plates (hexagons with indentations)
> 10-3° F – Dendrites (lacy hexagonal shapes)
Why are Snowflakes Symmetrical
First, not all snowflakes are the same on all sides. Uneven temperatures, presence of dirt, and other factors may cause a snowflake to be lop-sided. Yet it is true that many snowflakes are symmetrical and intricate. This is because a snowflake’s shape reflects the internal order of the water molecules. Water molecules in the solid state, such as in ice and snow, form weak bonds (called hydrogen bonds) with one another. These ordered arrangements result in the symmetrical, hexagonal shape of the snowflake. During crystallization, the water molecules align themselves to maximize attractive forces and minimize repulsive forces. Consequently, water molecules arrange themselves in predetermined spaces and in a specific arrangement. Water molecules simply arrange themselves to fit the spaces and maintain symmetry.
A Brief History of How photos have been taken of Snowflakes
Wilson Bentley (1865 – 1931) from Jericho, Vermont was the first person to capture photographs of snowflakes through the use of a microscope attached to a camera. His collection of 5,000 snowflake images introduced many people to the astounding diversity of snow crystals.
Wilson “Snowflake” Bentley – “Under the microscope, I found that snowflakes were miracles of beauty; and it seemed a shame that this beauty should not be seen and appreciated by others. Every crystal was a masterpiece of design and no one design was ever repeated., When a snowflake melted, that design was forever lost. Just that much beauty was gone, without leaving any record behind.”
In 1951, scientists from an organization now called the International Association of Cyrospheric Sciences (IACS) devised a classification system that characterized snowflakes into ten basic shapes. These shapes include the stellar crystals that many people are familiar with and odd snowflake forms such as capped columns. The IACS classification system is still in use today although there are other more complex classification systems as well.
Kenneth Libbrecht, Professor of Physics at the California Institute of Technology, has made extensive observations of how water molecules get incorporated into snow crystals. In his research, he has observed that the most intricate snowflake patterns are formed when there is moisture in the air. Snowflakes produced in drier conditions tend to have simpler shapes.
Temperature also has a large effect on the formation of snowflakes according to Libbrecht’s research. Snowflakes formed in temperatures below – 22 degrees Celsius (- 7.6 degrees Fahrenheit) consist primarily of simple crystal plates and columns whereas snowflakes with extensive branching patterns are formed in warmer temperatures.
Snowflake Questions and Answers
Is it true that no two snowflakes are identical?
Yes and no. No two snowflakes are exactly identical, down to the precise number of water molecules, spin of electrons, isotope abundance of hydrogen and oxygen, etc. On the other hand, it is possible for two snowflakes to look exactly alike and any given snowflake probably has had a good match at some point in history. Since so many factors affect the structure of a snowflake and since a snowflake’s structure is constantly changing in response to environmental conditions, it is improbable that anyone would see two identical snowflakes.
If water and ice are clear, then why does snow look white?
Not quite snowflake but definitely related and very interesting. The short answer is that snowflakes have so many light-reflecting surfaces they scatter the light into all of its colors, so snow appears white. The longer answer has to do with the way the human eye perceives color. Even though the light source might not be truly ‘white’ light (e.g., sunlight, fluorescent, and incandescent all have a particular color), the human brain compensates for a light source. Thus, even though sunlight is yellow and scattered light from snow is yellow, the brain sees snow as white because the whole picture received by the brain has a yellow tint that is automatically subtracted.
How big can snowflakes get?
Snowflakes are agglomerates of many snow crystals. Most snowflakes are less than one-half inch across. Under certain conditions, usually requiring near-freezing temperatures, light winds, and unstable, convective atmospheric conditions, much larger and irregular flakes close to two inches across in the longest dimension can form. No routine measure of snowflake dimensions are taken, so the exact answer is not known.
Is it ever too cold to snow?
No, it can snow even at incredibly cold temperatures as long as there is some source of moisture and some way to lift or cool the air. It is true, however, that most heavy snowfalls occur with relatively warm air temperatures near the ground – typically 15°F or warmer since air can hold more water vapor at warmer temperatures.
How does snow form if the ground temperature is above freezing?
Snow forms when the atmospheric temperature is at or below freezing (0 Celsius or 32 Fahrenheit) and there is a minimum amount of moisture in the air. If the ground temperature is at or below freezing, of course the snow will reach the ground.
However, the snow can still reach the ground when the ground temperature is above freezing if the conditions are just right. In this case, snowflakes will begin to melt as they reach this warmer temperature layer; the melting creates evaporative cooling which cools the air immediately around the snow flake.This cooling retards melting. As a general rule, though, snow will not form if the ground temperature is 5 degrees Celsius (41 deg Fahrenheit).
Why can snow fall when temperatures are above freezing?
Snow forms in the atmosphere, not at the surface. So snow can fall when surface temperatures are above freezing as long as atmospheric temperatures are below freezing and the air contains a minimum moisture level (the exact level varies according to temperature).
Does snow always get fluffier as temperatures get colder?
No. Studies in the Rocky Mountains have shown that the fluffiest, lowest density (0.01 – 0.05) snows typically fall with light winds and temperatures near 15°F. At colder temperatures, the crystal structure and size change. At very cold temperatures (near and below 0°F) crystals tend to be smaller so that they pack more closely together as they accumulate producing snow that may have a density (water-to-snow ratio) of 0.10 or more.
Why is snow a good insulator?
Fresh, undisturbed snow is composed of a high percentage of air trapped among the lattice structure of the accumulated snow crystals. Since the air can barely move, heat transfer is greatly reduced. Fresh, un-compacted snow typically is 90-95 percent trapped air.
How are snowflakes formed?
As covered above you should know this but to reiterate
The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way. Although the six-sided shape is always maintained, the ice crystal (and its six arms) may branch off in new directions. Because each arm experiences the same atmospheric conditions, the arms look identical.
Real Snowflake pictures
Watch an incredible time-lapse video of a snowflake forming
Some PDF Documents and Papers about Snowflakes and snowflake formation
> Snowflake Science
> The Science of Snowflakes
> Looking at Snowflakes – Shape and Structure
> Basic Snowflake Forms
> Universality in Snowflake Formation – Thesis
– Credit and Resource –
Snow Brains
Geology.com
AboutEducation
EarthSky
NOAA
In The Life of a Snowflake
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