Snowflake

A snowflake is a tiny ice crystal.

It starts around a tiny speck. Water turns into ice on that speck. The ice grows as it falls.

Changing air makes it grow. The air can be warm or cold. This changes the shape of the flake.

Snowflakes look white. This is because they bounce sunlight. But the ice is actually clear.

No two flakes are the same. They all have different patterns. Each one is special.

A snowflake is a single ice crystal.

It is large enough to fall as snow. Each flake starts around a tiny particle. This particle is called a nucleus. It might be a speck of dust or clay.

Water vapor in the air turns into ice on this nucleus. This is called deposition. As the flake falls, it grows. It moves through different air. The air changes in temperature and humidity. These changes decide the shape of the flake. Most flakes have six arms. This is because of how ice is built.

Some shapes are needles or columns. Others are flat plates. Most flakes are not perfect. In fact, very few are perfectly symmetrical. It is hard to find two that are the same. This is because a snowflake has many water molecules. There are about 10 quintillion molecules in one flake. Each one grows in its own way. Even though ice is clear, snow looks white. This happens because the many tiny parts of the flake scatter sunlight.

A snowflake is a single ice crystal. It is large enough to fall through the air as snow.

Even though ice is clear, snow looks white to our eyes. This happens because the many small facets of the crystals scatter sunlight.

Each flake begins its life around a tiny particle called a nucleus. This nucleus might be a speck of dust, clay, or even a biological particle. As the flake falls, it moves through different areas of temperature and humidity. These changing conditions make each snowflake grow in a unique way. This is why it is so hard to find two that are exactly alike.

Snowflakes grow through a specific way it works called the Wegener–Bergeron–Findeisen process. It starts when a water droplet freezes onto an ice nucleus. The crystal then grows by deposition. This means water vapor from the air turns directly into ice on the crystal surface. Because there are so many more water droplets than ice crystals, the crystals grow at the droplets' expense. The droplets evaporate as the crystals get larger. These large crystals can eventually collide and stick together to form clusters called aggregates.

Most snow that falls to the ground is made of these aggregates.

The shape of a snowflake depends on the weather it travels through. Most snowflakes show six-fold symmetry because of how ice is built. This creates a tiny hexagon with six arms called dendrites.

If the air is very cold, crystals might form as needles or columns. In warmer air, they often form as flat plates. Some flakes even become hollow prisms or thick rime frost. Scientists like Ukichiro Nakaya created diagrams to show how temperature and moisture change these shapes. He found that crystals in very moist air tend to be lacy and ornate. Meanwhile, crystals in drier air are often more solid and compact.

People have studied these beautiful shapes for a long time.

Starting in 1885, Wilson Alwyn Bentley used a microscope to photograph thousands of snowflakes. His work helped us understand the huge variety of shapes in nature. Later, researchers Magono and Lee created a system with 80 different shapes. They categorized them into groups like needles, columns, and plates. Some very large aggregates were even recorded in January 1887 at Fort Keogh, Montana. Those giant flakes were claimed to be 15 inches wide. Most snowflakes are much smaller, usually only three or four inches wide when they cluster together.

Snowflakes are more than just science; they are also important symbols.

In many places, people use the snowflake shape during the Christmas season. In some traditions, they represent purity. You might see a stylized snowflake on the emblem of the Winter Olympics. They are also used on snow tires to show they work well in winter. In Canada, a six-pointed snowflake is used for the Order of Canada. This honors the country's northern heritage. You can even find snowflake symbols in computer code and ancient poetry. They remind us of the many tiny patterns found in our world.

A snowflake is a single ice crystal large enough to fall through the Earth's atmosphere as snow. While individual ice is clear, snow appears white to the human eye. This happens because the many small crystal facets scatter sunlight between them. Each snowflake begins its life by forming around a tiny particle known as a nucleus. This nucleus can be a speck of mineral dust, clay, or even a biological particle. As the flake falls, it moves through changing zones of temperature and humidity. These shifting microenvironments cause each flake to grow in a unique way.

The growth of a snowflake follows a specific mechanism called the Wegener–Bergeron–Findeisen process. It begins when a water droplet freezes around an ice nucleus in a supersaturated environment. In these conditions, liquid moisture and ice coexist beyond their equilibrium point. The crystal then grows through deposition, where water vapor from the air turns directly into ice on the crystal surface. Because water droplets are much more abundant than ice crystals, the crystals grow at the expense of the droplets. This causes the droplets to evaporate while the crystals reach sizes of hundreds of micrometers or even millimeters.

As these crystals grow, they can collide and stick together to form clusters called aggregates. Most snow that falls to the ground consists of these aggregates rather than single crystals. While single crystals the size of a dime have been observed, most aggregated flakes are only three or four inches wide. However, history records a massive exception in January 1887 at Fort Keogh, Montana. During that time, aggregated snowflakes were claimed to be 15 inches wide. Some crystals also become encapsulated in rime frost, forming ice balls known as graupel.

The specific shape of a snowflake is determined by the temperature and humidity of the atmosphere. Most snowflakes exhibit a six-fold radial symmetry due to the hexagonal crystalline structure of ice. This structure starts as a minute hexagon, from which six arms called dendrites grow outward. While many flakes look symmetrical, empirical studies suggest that less than 0.1% of snowflakes show an ideal six-fold symmetric shape. Rarely, at temperatures around -2°C, snowflakes can even form with threefold symmetry, appearing as triangles.

Scientists have developed complex ways to classify these various forms. Ukichiro Nakaya created a morphology diagram relating crystal shape to temperature and moisture. He discovered that crystals in supersaturated air tend to be lacy and ornate. In contrast, crystals in air below saturation are more solid and compact. For example, freezing air down to -5°C promotes thin, flat plates. In much colder air, such as -15°C, crystals may form as hollow columns, prisms, or needles.

Beyond Nakaya's work, researchers Magono and Lee devised a classification including 80 distinct shapes. They grouped these into categories such as needle crystals, columnar crystals, and plate crystals. They also identified rimed crystals, such as graupel, and irregular snow crystals. This detailed study helps scientists understand the different types of precipitation. The variety is so vast that it is unlikely any two snowflakes are exactly alike. This is because a typical snowflake contains approximately 10^19, or 10 quintillion, water molecules.

Humans have studied these patterns for over a century. Starting in 1885, Wilson Alwyn Bentley used a microscope to photograph thousands of snowflakes. His work revealed the incredible diversity of shapes that exist in nature. Today, the snowflake remains a powerful symbol in many cultures. It is used in the emblems of several Winter Olympics and as a symbol of purity in some traditions. In Canada, a six-pointed stylized snowflake is used for the Order of Canada to represent northern heritage.

Snowflakes also appear in specialized technical and historical contexts. A snowflake symbol is used on snow tires to indicate they provide traction in winter conditions. In the Tang Dynasty, snowflake poetry served as a symbol for the Milky Way galaxy and cosmic energy. Even in modern technology, different snowflake symbols are encoded in Unicode. Whether viewed through a microscope or as a cultural icon, the snowflake connects the physics of the atmosphere to human creativity.