While at our remote camps, we've used tents. There are two types of tents in the field with us: Scott tents and an endurance tent. These take quite a while to erect and if there are high winds present, they can be very frustrating to set up as they require staking to the ground and placement of guy lines. The awkward frame structure of the Scott tents make them difficult to raise with strong winds present. Smaller, lighter mountain tents (the type most people think of when imagining a tent) get caught by the wind and are difficult to hold down to attach the poles.
As a result, the United States Antarctic Program's (USAP) field manual suggests building a snow shelter. They describe five possible structures: snow walls, trenches (of which there are two versions: with a snow-block roof, and using a tarp as a roof), snow mounds (Quinzhees), snow caves, and igloos. A sixth type, only used in dire emergencies are ledges cut into crevasses or bergshrunds (large cracks at the head of the glacier where it is beginning to flow). With these descriptions, they provide an estimate of length of time required to construct them (which could vary widely depending upon experience), as well as the pros and cons of each kind.
During "Happy Camper" class, I had the opportunity to construct two of these five structures: the snow wall and a snow-block roofed trench (1/2 to 2 hours). Just like its name suggests, a snow mound (2 to 4 hours) is simply a mound or pile of snow compacted over a pile of gear. Once the walls are thick enough, a hole is dug into the side and the gear is pulled out, leaving a cavern for people. F-Stop (Field Safety Training Program FSTP) used to teach the building of Quinzhees, but stopped because they take too long to build, and therefore, is not a realistic shelter in an emergency situation. They now focus on teaching the construction of snow trenches. A snow cave (3 to 4 hours) is also just like it sounds. It differs from a snow mound in that it is usually dug into a slope of snow instead of being built on level ground.
The final structure taught in the USAP Field Manual is the igloo (3-5 hours). According to the field manual, "Although igloos are by far the hardest shelters to build and should not be attempted in an emergency, they are warm, roomy, and aesthetically pleasing." Of all their shelter descriptions, those for an igloo are the most comprehensive due to the inherent difficulty in construction.
To construct an igloo, the manual first instructs one to scribe a circle in the snow with a "maximum diameter" of six feet. Cutting the snow blocks requires attention to detail as the size gradually builds to create a spiral base. Cutting snow blocks in Antarctica is quite easy because most snow down here is the ideal consistency. It is firmly packed (not powdery or sugary) and actually feels and sounds (when you're sawing it) just like styrofoam. The "ACME 'perfect' snow block" has the following dimensions: "Total saw length (length) x 1/2 saw length (width) x blade length (height)". The blocks are continually layered over the previous row with joints between them offset as in brickwork. Igloo construction is best attempted with at least two people; one person needs to be inside helping guide the blocks into their correct position. The final block in the top is tapered on all sides to fit like a cork. Finally, the inside person is responsible for constructing a tunnel for access to the igloo. Once completed, the floor and be dug deeper to provide more room inside.
Having slept in a snow shelter for the first time in "Happy Camper", I can attest to the protection they provide. Throughout the night, I was very warm and never felt the slight wind that was blowing. Some of those who chose to sleep in tents complained of the tent flapping keeping them awake; inside the snow trench it was almost silent. As I was a first time builder of a snow trench, it is true that my snow-block roofed trench was no where as "aesthetically pleasing" as a well-constructed igloo.