An igloo is a kind of building, made in the shape of a dome, with an opening that allows entry and exit, made with blocks of ice. These structures are very common in very cold areas. The Eskimos use these constructions to stay inside them, and in this way to be able to take refuge from the cold. Its lifting is usually very fast, since the main material for its manufacture is snow, so it can be very economical, being this a good alternative housing for the inhabitants of icy regions such as Alaska and Antarctica, where making other kinds of houses would be very expensive.
The snow used to make the igloo must be very firm and dense, for which, many times it must be compressed, and then cut into blocks similar to bricks to build the igloo, laying one on top of the other.
Igloos can be classified depending on their size: the largest ones are usually huge, permanent and durable structures, which are divided into sections or compartments, which serve as rooms suitable for accommodating up to 20 people. They can also be a sequence of medium and small igloos intertwined by tunnels, becoming a set of rooms in the snow. The medium-sized ones are used as a family home, they have a single room in their internal part, they last longer than the small igloos, so they need continuous maintenance to preserve the durability and resistance of the structure. The small ones are made with the purpose of serving as temporary shelterfor hunters and explorers, who travel the distant and snow-covered regions, and who cannot return home immediately and must spend the night in these structures to protect themselves from the wind. This kind of building is short-lived.
The warm atmosphere that can be felt inside an igloo welcomes a growing movement, since when it warms it expands, thinking less than the cold air, which will descend. So the hottest area of the igloo is in the upper part, where the rooms are usually located, the middle part is the kitchen and in the lower part is the entrance. These features are for those large igloos.
