View at EarthSky Community Photos. | Tawnya Silloway in Colorado submitted this imgae on January 23, 2025, and wrote: “I was able to photograph many fluffy snowflakes yesterday, but this one stood out because she brought a daisy.” Thank you, Tawnya!
Exquisite crystalline snowflakes capture the imagination. But what is the science behind their formation, and is it true there are no two snowflakes alike?
First of all, the temperature and humidity of the atmosphere determine the shapes of snowflakes. And snowflakes form in the atmosphere when cold water droplets freeze onto dust particles. Finally, depending on the temperature and humidity of the air where the snowflakes form, the resulting ice crystals will grow into a myriad of different shapes.
Temperature and humidity determine snowflake formation. Image via National Weather Service/ NOAA.
Wilson Bentley
Wilson Bentley (1865–1931) from Jericho, Vermont, was the first person to capture photographs of snowflakes through a microscope attached to a camera. His collection of over 5,000 images – no two alike – introduced many people to the astounding diversity of snow crystals.
Wilson “Snowflake” Bentley, who photographed over 5,000 snowflakes between 1885 and 1931. Image via Wikimedia Commons (public domain).Snowflakes by Wilson Bentley showing a range of shapes. Image via Wikimedia Commons (public domain).
Classification systems
In 1951, scientists from an organization now called the International Association of Cryospheric Sciences (IACS) devised a classification system that characterized snowflakes into 10 basic shapes. Kenneth Libbrecht, professor of physics at the California Institute of Technology, in his guide to snowflakes at SnowCrystals.com, provides this chart of 35 types of snow crystals. They range from ice fragments to rods to the much more complex fern-like dendritic flakes we are all familiar with.
View larger. | Here’s a chart from Kenneth Libbrecht’s SnowCrystals.com website that shows 35 types of snowflakes. Image via Kenneth Libbrecht. Used with permission.
How snowflakes form from water vapor
Libbrecht has made extensive observations of how water molecules get incorporated into snow crystals. In his research, he observed that the most intricate snowflake patterns form when there is moisture in the air. Snowflakes produced in drier conditions tend to have simpler shapes.
According to Libbrecht’s research, temperature also has a large effect on the formation of snowflakes. Snowflakes formed in temperatures below -7.6 degrees Fahrenheit (-22 degrees C) consist primarily of simple crystal plates and columns. Meanwhile, snowflakes with extensive branching patterns are formed in warmer temperatures.
Visit Libbrecht’s website SnowCrystals.com for a wealth of information about snowflakes, including short videos of lab-grown snowflakes forming.
Fiona M. Donnelly captured these snowflakes in Smiths Falls, Ontario, on January 3, 2018. Used with permission.
A gallery of snowflakes by Wilson Bentley
A spiky dendritic snowflake by Wilson Bentley. Image via Wikimedia Commons (public domain).A simple hexagonal plate snowflake photographed by Wilson Bentley. Image via Wikimedia Commons (public domain).A complex and delicate dendritic snowflake by Wilson Bentley. Image via Wikimedia Commons (public domain).One of the snowflakes photographed by Wilson Bentley. Image via Wikimedia Commons (public domain).
Snowflakes from our community photos
View at EarthSky Community Photos. | Lisa Ann Fanning in Monmouth County, New Jersey, captured this image on January 19, 2024, and wrote: “Our first significant snowfall in 2 years presented opportunity to “play.” I enjoyed macro-photographing snowflakes gathered on a cloth outside my window. When you have a chance to see them in detail, they really are quite stunning!” Thank you, Lisa!View at EarthSky Community Photos. | Judy Boyle in Whitehall, Montana, captured this image on January 7, 2024, and wrote: “I was taking my Border Collies for a walk, and it began to snow. I notice this uniquely perfect snowflake on the black fur of one of the dogs. Knowing he wouldn’t stand still for a picture, I carefully picked it off and put it on my glove.” Thank you, Judy!View larger at EarthSky Community Photos. | Sheryl R Garrison in Southern Alberta, Canada, captured this lovely closeup image of a snowflake on November 9, 2022. She said: “Every winter I try to photograph snowflakes in honor of Wilson (Snowflake) Bentley, the first person to photograph a single ice crystal in 1885. While he would capture them on black velvet, I enjoy hunting for them on natural surfaces. This snowflake was photographed on a raspberry leaf. The temperature was -18 C [-.4 F].” Thank you, Sheryl!
Did you capture a great shot of a snowflake? Submit them here.
Bottom line: Temperature and humidity influence snowflake shape. The most intricate snowflake patterns form during warm and wet conditions.
Deanna Conners is an Environmental Scientist who holds a Ph.D. in Toxicology and an M.S. in Environmental Studies. Her interest in toxicology stems from having grown up near the Love Canal Superfund Site in New York. Her current work is to provide high-quality scientific information to the public and decision-makers and to help build cross-disciplinary partnerships that help solve environmental problems. She writes about Earth science and nature conservation for EarthSky.
