Snow

Snow consists of individual ice crystals that grow in the atmosphere and then fall to the ground. It is frozen water from the moment it forms until it melts away.

Snowstorms happen when there is enough moisture and cold air. Snowflakes start from tiny particles in the air. They attract supercooled water droplets that freeze into beautiful crystal shapes. These crystals can look like tiny plates, needles, or columns. When lots of snow collects, it becomes a snowpack. The snow can pile up in drifts and change over time.

Major snow-prone areas include the polar regions, the northern half of the Northern Hemisphere, and mountains around the world. In the Southern Hemisphere, snow is mostly found in mountains and Antarctica.

Snow affects many things people do. It can make transportation harder, so roads, airplane wings, and windows need to be cleared. Snow also helps agriculture by giving water to crops and keeping animals safe. Many enjoy sports like skiing, snowboarding, and snowmachine travel thanks to snow. It is also important for ecosystems, protecting plants and animals during winter.

Precipitation

Snow forms in clouds that are part of bigger weather patterns. Snow crystals start from tiny drops of water that freeze in cold air. They grow into many shapes, depending on temperature and moisture. These crystals then fall to the ground as snow.

Snow clouds often appear in areas where air pressure is low, where warm air meets cold air. They can also form near big bodies of water, like lakes. When cold air moves over warmer water, it picks up moisture and creates snow on the shore downwind. Mountains can also make snow when moist air is pushed upward, cools down, and forms snow as it moves down the other side.

Accumulation

Snow builds up from many snow events in cold places, like the Arctic, Antarctic, and high mountain areas. We can measure how much snow has fallen by using special tools that melt the snow and count the water it makes.

Different kinds of snow events exist, from light flurries to big blizzards. A blizzard is a severe snowstorm with strong winds and low visibility. Snow can fall in different amounts, and scientists measure new snow with a board to keep track of how much falls each day.

Some places get a lot of snow. For example, a mountain in the United States once got a lot of snow in a season, and a town in Japan gets a lot of snow each year. The biggest snowflake ever recorded was very large!

Metamorphism

Snow changes shape and texture from the moment it lands until it melts or turns into glacier ice. It starts as light, powdery snow and becomes denser and more granular over time. This happens because the snow is pressed down by its own weight, blown by the wind, and goes through cycles of melting and refreezing. Water vapor can add tiny ice crystals, called hoar frost, when the weather is very cold and still.

Over time, snow can either melt away or turn into a type of snow known as firn. In colder climates, snow may stay on the ground all winter. By spring, it usually becomes about half as dense as water. If it lasts into summer, it changes into névé, a type of granular snow that has partly melted, refrozen, and compacted.

Main article: Firn

Movement

Snow can move in several ways after it lands on the ground. One way is through drifting, where wind pushes loose snow into piles. This drifted snow can sometimes cause a avalanche on steep slopes. An avalanche is a fast-moving slide of snow down a hill.

Another way snow moves is through melting. In spring, snow often melts and feeds rivers. This melting can cause rivers to flood.

Over many years, snow can also turn into glaciers. When snow piles up, it compresses into ice and slowly moves downhill.

Main article: Avalanche

Main article: Glacier

Science

Scientists study snow in many ways. They look at how snow forms and how it changes. They also study how snow affects rivers and nature. Scientists use tools like satellites and ground checks to measure snow. This helps engineers make better vehicles for snowy areas and helps farmers understand how snow affects water.

Snow scientists also group snow based on its features, like how thick it is or how it looks under a microscope. They measure things like how much land is covered in snow and how deep it is. Satellites help them watch snow from space. These checks show that snow cover has been changing in many parts of the world. These changes are linked to climate change, which can make snow melt earlier or cover less land.

Effects on civilization

Snow changes many parts of our lives, especially travel, farming, buildings, and fun winter activities. It can make it harder to travel by car, train, or plane, but it also helps farms by giving water when it melts. Buildings need to be strong enough to hold up snow, and people enjoy many sports like skiing and snowboarding in the snow.

When snow falls, it can slow down cars on roads, trains on tracks, and planes on runways. Roads often use special tires and chemicals to keep traffic moving, while airports use brushes and snowplows to clear runways. Trains use snowplows to clear tracks and sometimes special structures to keep snow from covering the tracks. Farmers sometimes use fences to guide snow into places where it can melt and provide water for crops later on.

Snow is also important for farming because it acts like a blanket, keeping the ground warm and protecting plants from very cold temperatures. When the snow melts in spring, it provides water that helps crops grow. Many rivers get a lot of their water from melting snow, which is important for irrigation.

Buildings must be built to handle the weight of snow on their roofs. Engineers use special rules to make sure roofs and power lines can support snow without breaking. In winter, people enjoy many activities in the snow, such as skiing, snowboarding, and snowmobiling. Ski resorts often make their own snow to keep slopes covered longer.

Main article: Winter sport

Main article: Cold-weather warfare

See also: Ski warfare

Effects on plants and animals

Plants and animals in snowy places have special ways to stay safe. Plants can rest or keep energy in seeds. Animals might sleep deeply, stay warm together, or make things to stay unfrozen.

Snow changes how plants grow and where they live. Trees, like conifers, can hold snow in their branches. Snow can keep water for plants, but it must melt before plants can grow. Sometimes, melting snow can move plants and change the land.

Many tiny animals live in or under the snow. Insects like spiders, wasps, beetles, snow scorpionflies, and springtails stay active in cold weather. Small animals like voles and pikas keep food under the snow to eat later. Bigger animals like wolves, coyotes, foxes, lynx, and weasels look for these smaller animals in the snow.

Outside of Earth

Snow isn't just for Earth! Other places in our Solar System have their own kinds of snow. On Mars, there is water snow that falls in the far north and south, and carbon dioxide snow that helps make the poles even icier in winter. On Venus, a special metallic dust looks like snow on the tallest mountains.

On Saturn's moon, Titan, there is methane snow, and on Pluto, methane frost falls from high places. These different kinds of snow show how snow can appear in many places far from Earth!