Igloo Effect
Igloo effect works well with snow, not ice.
When snow crystals drop on each other and creates a pack of ice crystals it is essentially a structure of the crystals with air filled spaces. That is the reason why the equal volumes of snow and ice do not weigh the same. Snow is lighter.
Igloo effect is the name given to the insulation provided by a walls of snow on a body due to the air pockets within it which keeps the temperature dropping below zero degrees as well protects you from wind chill.
Of course the inner walls will melt due to radiation and conduction of heat from the bodies of humans and animals within the igloo but it can be kept alive with some maintenance.
Igloo effect makes sense in sub zero temperatures only. It is better to be at zero degree C or F when the temperature outside is minus two digits.
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