i love cold weather!

I dislike heat. I love cold weather. I'm another form of water. I'm made when it is below zero. The warmer it is, the more sweat I drop and I become smaller. I can also be produced by freezing. You can eat me. I can protect foods from decaying. I naturally appear during the winter, but people need me in summer. Now man himself can make me in any season.



what am I ?