Ukraine soldier writes....
“From my own experience, I will say that during a severe frost — about minus 20 Celsius to minus 30 Celsius — the optimal time for a serviceman to stay outside is no more than 90 minutes,” ....said Petro Oleksiuk, 27, who served in the Ukrainian army from 2014 to 2015.
However, at many locations there aren’t enough available soldiers to constantly rotate patrols.
“In reality, neither we nor the enemy have enough people for this, therefore the schedule remains the same even in the most severe frosts,”...Therefore, the warriors try to dress as warmly as possible, using the principle of layering of clothes, and eat as high calorie as possible”.
I lived and worked at -60.