Why Does It Snow and How Does Snow Form?

(Last Updated On: October 22, 2019)
How Does Snow Form?

Snow. It can bring both joy and anguish throughout the winter seasons. On the one hand, it is a great opportunity to get outside and partake in one of many snowy activities. But it can also cause a lot of calamities, like dangerous driving and walking conditions. 

Many of us have lived with snow for so long, we’ve never given much thought to how it is actually formed. Or why it snows in the first place. Thankfully, we’re here to clear a few things up.

How Does Snow Form?

Snow formation starts before temperatures even reach freezing. When warm and cool air collides, the water vapor in the warmer air rises with it. Once the water vapor is at a higher altitude, clouds are formed from the vapor cooling down and turning back to liquid. The vapor that turns into ice will form around small particles, such as dust or dirt, and make ice crystals. These become the seeds for forming snowflakes.

Snow begins to form when the cloud reaches an atmospheric temperature of below 0°C (32°F): the ice crystals continue to grow as the water vapor freezes onto their surfaces. Snowflakes are formed when these ice crystals come in contact with each other and start forming symmetrical patterns. 

When the air becomes warmer, these ice crystals melt around the edges slightly, and can clump together.

Fun fact: There are many types of snowflake (or snow crystal) shapes, but each snowflake formed is one-of-a-kind.

Why Does It Snow?

Why Does It Snow?

As ice crystals continue to stick together, the snowflakes get bigger and heavier and they fall collectively as snow. Contrary to popular belief, it can still snow when the temperatures are above 0°C and will maintain its form if it stays roughly below 2°C. 

The type of crystal formed, and whether you’ll get wet or dry snow, depends heavily on the temperature and atmospheric conditions. Snowflakes that fall through cold and dry air will end up being small and powdery — this will be your “dry” snow that doesn’t clump together. On the other hand, the snowflakes that fall through warmer, moist air, clump together to form “wet” snow.

Types Of Ground Snow

You may have noticed that snow settles differently. It can be dry and powdery or wet and slushy — this all depends on the ground conditions. Here’s a list of different types of ground snow:

Powder Snow

Freshly fallen snow settles in a powder-like fashion if temperatures are below 0°C and the air is dry. Powdery surfaces are a snowboarder and skier’s dream, as it produces the perfect conditions for them to ride through the snow. However, since they are so small and light, any gust of wind can cause them to drift and decrease the visibility in the mountains.


Over time, as powdery snow gets walked on and pushed around, it becomes crud. It is compacted in certain areas and lumps start to form. The snow is still relatively soft to walk on and is still “dry” to the touch.


When the sun beats down on the snow and warm winds melt the top, a crust forms. This is the most satisfying to walk on when the snow is undisturbed, as you’ll feel a crunch when you step into the perfectly flat surface and reveal soft snow underneath.

Packing Snow

This is what you get when the snow is near its melting point. The snowflakes are still intact but are all stuck together, which makes it easy to shape. Packing snow is perfect for making snowballs and building snowmen! For those who are more ambitious, this is also perfect for making an igloo in the backyard.

You might also like: Why Do We Build Snowmen?


As the temperatures warm up, the snow continues to melt into a mud/slush concoction. This can be a nightmare to walk through, but generally means that the snow will be going away soon.

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