A map with snow.
Winter Mode was a randomly occurring map type for Minecraft Alpha. It was added on the 9th of July, 2010 and is the first "biome" to appear in Minecraft. Although behaving somewhat like a biome because it would alter the environment it is not a biome as they are today. Winter mode affected the entire world but a biome only effects portions. Worlds generated having this mode could not be changed back to the normal mode and vice versa naturally. Players could, however, force their savegame into Winter Mode by activating the SnowCovered parameter in level.dat using a map editor.
The Halloween Update disabled the snowfall effect and made Winter Mode obsolete (snow effect is still in game files), because snow is now area-dependent, as one of many biomes.
Differences
One of the differences is falling snowflakes. There are only four different kinds of snowflakes. These snowflakes will create Snow tiles on any tile that is directly exposed to the sky, provided it's solid. Unlike Grass, Snow will not spread onto tiles under cover. A light source can be placed next to it in order to melt the snow. Snow can be broken by hand or with tools, and a shovel can be used to produce snowballs, which can then be thrown or crafted into snow blocks. Snow will automatically break if a block is placed on it and will hover in the air if placed over a half block.
The second unique element is Ice. When a map is generated, all exposed water blocks are frozen into Ice, which is semi-transparent and slippery. Ice can be changed back to a spring tile by hand or with a pickaxe if speed is preferred. Like snow, it can be melted by being placed in proximity to a light source.
See Also