Snow falls from the sky, but where exactly does it come from? Is it a cloud, breaking up into little pieces? Or is there a giant living up there, who has made a bunch of really cold paper confetti he feels like throwing around??
You've probably noticed that it only snows when it is very cold outside, and if you know about how water becomes ice when it gets cold, then you might think snow must be frozen rain. Generally, frozen rain is what is referred to as "sleet" while snow is actually frozen water vapor. "Water vapor" refers to water when it's in the form of a gas instead of in the form of a liquid (such as rain or drinking water) or a solid (such as ice). You might not have heard of it before, but even though water vapor is invisible, it’s all around us and it plays a big part in everything from snow to rain to clouds and more!
When cold temperatures change the water vapor in the atmosphere directly into the solid state of ice (without first passing through the liquid stage), it creates snow that then showers down out of the sky! (Or, if the transformation happens closer to the ground on a cold surface, it creates frost.) As soon as the temperature warms up again, the snow usually melts back into liquid water! – This is all part of the awesome process of The Water Cycle!