The Science of Snow

There are 35 basic snowflake shapes. 

At 19 years old, Wilson A. Bentley was the first person to take close-up photographs of snowflakes.

Snow is made of tiny ice crystals. Snow forms super high up in the clouds. Water freezes into tiny snow crystals up in the clouds. If those crystals of ice get heavy enough, they fall down from the clouds as snow. On the way down, the tiny ice crystals bump into one another and then clump together to form snowflakes.

Snow and rain are types of precipitation (water that falls to the earth). Snow is frozen precipitation.

Snow is almost 90% air and clear (it only appears white because of how the winter sunlight reflects off of it). Every snowflake is unique, but scientists can sometimes find two snowflakes that look alike.

Wonder what makes a snowflake’s shape? The crystal shape is based on temperature, air moisture, and the direction and speed at which the snowflake falls.

Animals will grow “winter coats” that are white. This helps them stay camouflaged from predators while in the snow.

If there is a form of precipitation, the air temperature needs to be at or below freezing for it to snow. Snow melts when it’s warmer than 32 degrees.

Snow is one of the six main forms of precipitation. The others are called drizzle, rain, sleet, graupel, and hail. Have you ever heard of graupel? It is basically just a really soft version of hail.

Snowflakes almost always have 6 sides. But they can have 3 or 12 sides every once in a while.

1,000,000,000,000,000,000,000,000 (1 septillion) snowflakes fall every winter.

Snowflakes can take two hours to travel from a cloud to the ground (but usually, it takes about one hour for a snowflake to reach the ground).

For the Winter Olympics, people have to use snow machines to make enough snow.

Snowy cities have places to put all the plowed snow…these giant piles can last until summer.

“Thundersnow” is a rare thunderstorm that happens while it is snowing.

You need to wear sunglasses in the snow. We usually associate sunny weather and sunglasses with summer and heat. However, snow has the ability to reflect a high level of ultraviolet radiation, which can burn your eyeballs and cause “snow blindness” if you do not wear protection.

It is never too cold for snow. While it can certainly be too warm for snow, there is no temperature too cold for snow. If snow does not happen in extremely low temperatures, it is just because there was no water or moisture in the air or the weather. It is frozen water after all, so water is necessary.

Have you ever heard of sleet? It may look like snow, but it is a little different. They are tiny, rainy particles that started out as water and froze on their way to the ground.

Have you ever seen frost in your front yard? While it may look like snow, it is not – it is actually made from water that was already on your ground or grass. The water froze because of low temperatures and looks a little bit like snow.

Japanese macaques love to make and play with snowballs; that’s one reason they are called “snow monkeys.”

Blizzard: A violent winter storm that combines subfreezing temperatures, strong winds, and snowfall. To officially qualify as a blizzard, a storm must reduce visibility to less than a quarter of a mile and last for at least three hours.

Cornice: An overhanging accumulation of ice and wind-blown snow, such as might be found on a cliff face.

Column: A type of snowflake that is shaped like a six-sided column.

Dendrite: A type of snowflake that has six points. This is the archetypal “snowflake” shape.

Finger drift: A narrow snowdrift across a roadway. So named because several of them together resemble the fingers on a hand.

Firn: Snow that is more than a year old, especially on the upper part of a glacier, but that has not yet consolidated into ice.

Flurry: A brief snowfall that produces little to no accumulation.

Graupel: Also called snow pellets, graupel refers to round, opaque snowflakes that almost look like polystyrene pellets. They form when regular snowflakes fall through ice-cold liquid clouds. Droplets from the clouds freeze onto the crystals, forming a solid mass. Graupel is similar to hail, but is smaller and less dense.

Ground blizzard: A windstorm that is not accompanied by snowfall, but which reduces visibility by lifting existing snow from the ground.

Lake-effect snow: Snow produced when icy winds move across a large body of warmer lake water. Common in the Great Lakes region of the U.S. and Canada.

Needle: A type of snowflake that is much longer than it is wide.

New snow: Recent snowfall in which individual ice crystals can still be seen.

Old snow: Snowpack in which individual snow crystals can no longer be recognized.

Perennial snow: Snow that remains on the ground for more than a year.

Pillow drift: A wide, deep snowdrift across a roadway.

Polycrystal: A formation made up of several snowflakes that fuse into one massive flake.

Rimed snow: Snowflakes coated in tiny frozen water droplets called rime.

Ripples: Marks on the surface of snow, similar to the ripples in sand, caused by wind.

Roller: A naturally occurring cylinder of snow formed by the wind.

Sastrugi: Irregular grooves and ridges in snow caused by the wind.

Sleet: Rain mixed with snow.

Slush: Partially melted snow on the ground.

Snirt: Snow mixed with dirt.

Snow bridge: An arch formed by snow and wind.

Snowdrift: Snow on the ground that has been blown by the wind to a height greater than the actual amount of snow that has fallen.

Snow squall: A brief, intense snow shower that does not qualify as a blizzard due to its short duration.

Snowburst: An intense snow shower that produces a lot of accumulation in a short period of time.

Snowflake: A cluster of ice crystals that falls from a cloud.

Snowstorm: Any weather event that features large amounts of snowfall.

Sun cups: Shallow, bowl-shaped hollows formed by irregular patches of intense sunlight.

Whiteout: a blizzard or squall that reduces visibility to near zero.