How Does Snow Form?

Moisture and temperature are key components in snow formation.

Snow, the big soft flakes we are familiar with, does not begin in this state. The process of forming into snow begins high in the earth's atmosphere. The formation of these powdery flakes of snow depends on many factors taking place. Moisture and temperature levels are important factors in the formation of snow.

Snow begins as a tiny ice crystal, or even a small speck of dust. When there is a lot of moisture in the air, condensation starts to occur. These tiny drops of condensation start to stick together. If the temperature in the higher atmosphere is cold enough, these tiny drops start to freeze and become ice crystals. This is how ice crystals, and eventually snowflakes, get their varying shapes. The moisture droplets cling and freeze together randomly.

As more moisture collects and freezes together, the drops begin to get heavier and start to fall toward the ground. These ice crystals may pass through several different degrees of temperature changes as they plummet to the ground. This is how they fall as rain, sleet or snow.

Besides the random clinging and freezing of the droplet of water, other variables affect how the snowflake will eventually have its own unique shape and design. Things such as how fast the ice crystal falls to the ground and how cold the temperature is that it passes through will also effect the snowflake's final shape.

As the snowflake falls to the ground, it may pass through surface air that is warmer or cooler. Melting and refreezing will take place, causing the snow to form into many different intricate shapes, until it finally reaches the ground.

Even after the snow reaches the ground, it continues to change shape as it melts and melds with the other snowflakes. The snowflake then looses all of its intricate patterns. If the surface temperature is very cold, the snow will form a hard crusted top. If it is warm, the snow may start to melt and become slushy.

Resources

• SYR: Snow and Ice Information