Nepedia
Back to Discover
Advanced Reader
🌍

Snow

earth science Maturity 7-9 Vital Level 3 Next article →

Snow is a form of frozen crystalline water that forms in the atmosphere. It begins as individual ice crystals growing while suspended in clouds. Once these crystals reach a certain size, they precipitate and fall to the ground. Upon landing, they accumulate in layers known as a snowpack. This snow can undergo various changes, such as melting or turning into ice. In very cold climates, this accumulation can lead to the formation of massive glaciers.

Watercyclesummary
Watercyclesummary

The formation of a snowflake is a complex physical process. It starts when tiny, supercooled water droplets freeze around a nucleus. A nucleus is a small particle like dust, clay, or biological material. These droplets can remain liquid even below freezing temperatures. Once the first ice crystals form, they grow through a process called diffusion. In this process, water vapor from the air moves onto the ice surface. Because water droplets are more numerous than ice crystals, the crystals grow larger through the Wegener–Bergeron–Findeisen process.

Snowflakes display a wide variety of distinct shapes and structures. These shapes depend on the specific temperature and moisture levels in the atmosphere. Scientists like Ukichiro Nakaya developed diagrams to show these relationships. Basic shapes include platelets, needles, columns, and rime. Some crystals form as solid plates or hollow prisms. Others develop into delicate, lacy dendrites when the air is supersaturated. When many of these crystals collide and stick together, they form larger clusters called aggregates.

Feathery Snow Crystals (2217830221)
Feathery Snow Crystals (2217830221)

Different weather systems can trigger significant snowfall events. Mid-latitude cyclones are low-pressure areas that can cause everything from mild snow to heavy blizzards. A blizzard is a specific, intense condition. In the United States, it requires winds of 35 miles per hour or higher for at least three hours. It also requires visibility to drop below 1/4 mile due to snow. Another type is a frontal snowsquall. These are intense lines of precipitation that can create whiteout conditions.

Feb242007 blizzard
Feb242007 blizzard

Local geography also plays a major role in how snow falls. Lake-effect snow occurs when cold air moves over warmer lake water. The air picks up moisture and rises, freezing as it moves downwind. This creates intense bands of snow in areas called snowbelts. Mountains also create snow through orographic or relief snowfall. This happens when wind forces moist air up a mountain slope. As the air rises, it undergoes adiabatic cooling, which leads to condensation and precipitation.

Lake Effect Snow on Earth
Lake Effect Snow on Earth

Historically, scientists have worked hard to classify the diversity of snow. Israel Perkins Warren was an early researcher who studied thousands of crystals. Later, researchers like Magono and Lee identified 80 distinct shapes of freshly formed snow. Micrography, or the use of microscopes to photograph crystals, helped reveal these patterns. These studies allow us to understand the complex variables of cloud physics. By studying the crystals, we can learn about the temperature and humidity of the atmosphere.

Snowflakeschapte00warriala-p11-p21-p29-p39
Snowflakeschapte00warriala-p11-p21-p29-p39

Snow has a massive impact on both the natural world and human society. In ecosystems, snow provides an insulating layer that helps plants and animals survive winter. For humans, snow affects transportation, requiring us to clear roads and airplane wings. It is also vital for agriculture, as it protects crops and livestock. In the spring, seasonal melting provides necessary runoff for rivers and groundwater. Finally, snow supports many recreational activities, such as skiing and snowboarding.

Earth-satellite-seasons
Earth-satellite-seasons
550 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (28)
File:Countries receiving snowfall.svg
Countries receiving snowfall.svg
File:Feb242007 blizzard.gif
Feb242007 blizzard.gif
File:Snowsquall line-Bourrasque neige frontal NOAA.png
Snowsquall line-Bourrasque neige frontal NOAA.png
File:Lake Effect Snow on Earth.jpg
Lake Effect Snow on Earth.jpg
Snow day in Adachi Tokyo - 2018 1 22.webm
File:Feathery Snow Crystals (2217830221).jpg
Feathery Snow Crystals (2217830221).jpg
File:Snowflakeschapte00warriala-p11-p21-p29-p39.jpg
Snowflakeschapte00warriala-p11-p21-p29-p39.jpg
File:Earth-satellite-seasons.gif
Earth-satellite-seasons.gif
File:Winter Storm Jonas 2016 NYC Pershing Square.jpg
Winter Storm Jonas 2016 NYC Pershing Square.jpg
File:Snow-covered fir trees.jpg
Snow-covered fir trees.jpg
File:Sparkling-snow.crystals.jpg
Sparkling-snow.crystals.jpg
File:Svalbard-Sastrugi-Snow.jpg
Svalbard-Sastrugi-Snow.jpg

+ 16 more

More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.