These constructions are preferable to anything standing above the surface because they are much more resistant to strong winds, and being less exposed, tend to conserve energy better. A real-life example of an improvised shelter after a Patagonian blizzard near the Glacier of Tears . On the background, the entrance of the Motoco Valley , which has puzzled climbers and explorers for decades due to its seemingly impossible walls. These underground shelters can be constructed with premeditation, or as improvised means when you face a climatic emergency while trekking. If you plan to build a shelter of this kind, you should not only calculate its structural resistance to strong winds, but also to the weight of heavy snow and the action of the sun.
Plastics tend to degrade easily on higher elevations.
Another view of the same shelter. The ponchos, sealed with duct tape can be seen, as well as some explorers, including one cooking with Napalm , which comes as a very handy fire starter and combustible. Improvised shelter, indeed, will not imply such elucubrations. You will be usually in such a hurry to prepare them that no time allowance will likely develop in order to allow you to prepare your new shelter for future usage, but if you can, by all means, think about the future. One of the best ways to improvise an underground or semi-buried shelter takes just the construction of a small 30 cm.