Snow fort
A snow fort is a usually open topped temporary structure made of snow walls that is used for recreational purposes. They are generally built by children as a playground game or winter pastime, and are used as defensive structures in snowball fights, but also built and used for make-pretend games such as "house" or "store".
Along with the snowman, it is one of two structures commonly built by children out of snow.
Variations
Snow forts consist of walls of piled and compacted snow. They may be "open" or "closed", that is, a person in the snow fort may be completely surrounded by the walls on all sides, there may be a "door", or the person may be completely exposed except in one direction. The last variation is used for snowball fights where opponents have forts facing each other and attack exculsively from their own fort, and is also used in "store" games as a counter. Existing structures such as the walls or concave corners of a building can be used as part of the snow fort, allowing for faster and easier construction of a snow fort.
Snow forts are usually at least knee-height and one-roomed with ones built for snow fights higher, but ones built for "house" may have even lower walls and multiple rooms. When used for snowball fights, snow forts often have sections where the wall is lower through which its occupants throw snowballs.
Construction
Snow forts may be contructed by piling and compacting snow to form walls. A common way to pile the snow is by moving one's legs together with snow between them. Another common way is to put snowballs together as if they were bricks; however, many other ways are practised. Water may be poured on the snow such that when it freezes the fort becomes stronger.
The ideal type of snow to use is snow that has recently fallen, about an hour before building the fort, on a day when the temperature is between 0 and -5 degrees Celsius. If it is colder, there is not enough moisture to bond the snow together. If it is above freezing, the fort will gradually melt.
See also: Igloo