SNOW

Snowflakes form when water vapor freezes into ice crystals in cold clouds.  The ice crystals attract cooled water droplets to form various shapes.  They get heavy and fall.  If the air is cold enough, the snow falls all the way to the earth without melting.  If the ground is freezing, the snowflakes stick to the ground. 

No Two Alike?
   The shape of snowflakes depends on the temperature of the air.  In colder air, the snowflakes may look like needles or rods.  When the air is a little warmer, the shapes can become very complicated.  Scientists have never been able to find two six-sided snowflakes that are exactly alike, though some of the simpler shapes can be twins.