Frost crystals appear to fall in front of winter trees. Frost crystals grow from water vapor in the air, just like snow flakes. But while snow flakes form on suspended dust particles high in the clouds, frost crystals form near the ground -- on windows, blades of grass, or just about any other solid surface.

Frost crystals appear to fall in front of winter trees. Frost crystals grow from water vapor in the air, just like snow flakes. But while snow flakes form on suspended dust particles high in the clouds, frost crystals form near the ground -- on windows, blades of grass, or just about any other solid surface.