Why is the temperature below zero civilized?

It's 27 degrees below zero, which generally won't melt, otherwise there is no need to remove snow. Negative 2 degrees, it is possible, because 1), the altitude of land is generally higher than sea level, so the actual pressure is lower than the theoretical pressure, which will lower the melting point; 2) There are impurities in ice and snow, which will lower the melting point. So the temperature is MINUS 2 degrees or even lower, and ice and snow may melt.