I'm Dreaming of a White Christma- NO! PLEASE, NO!

December has been and gone, and now the New Year is upon us. In past years, January has brought us the gift of snow (or burden, as many more might like to think of it). Nevertheless, whether you love it or you hate it, snow could well be on its way.

Between the more common of sights, rain, and the white powder that falls from the heavens, snow, we have sleet. Sleet is rain that has frozen whilst falling down to Earth from the clouds, and is not a very pleasant weather to get caught in; it feels like rain is being thrown at you, rather than falling on you. This is very often confused with actual snow.

Snow is a more peculiar phenomenon. It is a form of precipitation made of snow crystals which fall from the clouds. These snow crystals are formed when water vapour within a cloud freezes. The details of this process are more complex but here's the 'nub and jist' of it:

     > in 'cold clouds', droplets of water vapour remain in their liquid state far below water's freezing point, because in order to freeze, certain molecules within the droplet need to bond together to form the necessary ice lattice at the heart of the droplet.

     > otherwise, in warmer regions of cloud, all it takes is a dust particle to come into contact with a droplet, et voila, a snow crystal is formed.

These snow crystals then begin to grow, and they can do this by two methods:

1. Coalescence
2. Deposition

You can think of a crystal growing by coalescence as a sponge; its environment is heavily saturated with water vapour and it engulfs (sticks to, absorbs) any droplets it collides with, growing in size and weight with each mouthful.

The water droplets freeze directly onto a crystal growing by deposition, until it is heavy enough to fall through the cloud, towards the ground.

Both these processes are employed by most snow crystals, and as they fall, they come into contact with more and more crystals and droplets. These accumulations are our snowflakes.

Have you ever found a weird and wonderful snowflake? If you have, drop us a comment! Cheerio! :)

References: Wikipedia, about.com, enotes