Snow

Snow is a block modifier. When a map is generated, there is a chance that snow will be falling (dubbed "Winter Mode" by players). Any block which doesn't have another block vertically above it at any height will develop a layer of snow. Snow can be removed in the same way that any other block is destroyed. Placing a torch will melt any snow around it and will prevent it from developing. This is also the case for lava and active furnaces.

Creating a block on top of snow will make it hover in the air, as if the snow occupied a whole block. A layer of snow will hinder natural grass regrowth. Snow will not damage tilled and hydrated field areas, nor will it protect those plowed fields from being "trampled." It is also unaffected by glass, and will fall through and leave snow piled on the area below the glass.

This was added on July 9th, 2010, along with the addition of ice.