An important reason why caves are warm in winter and cool in summer is that they have a thick "roof". On the top of the cave in northern Shaanxi, pedestrians can walk or even take a truck. Even brick kilns and earthen kilns should be covered with a thick layer of soil to keep the cave warm, just like air conditioning.

In addition, the top and wall of the cave can neither directly absorb heat from the atmosphere nor directly dissipate heat to the atmosphere, only the hole can directly contact with the outside world. Therefore, the temperature change in the cave always lags behind the external temperature change, and the temperature difference changes little.

The temperature in the cave changes little in winter and summer. Because of its good thermal insulation performance, it is warm in winter and cool in summer. The cave was dug on the hillside, so its "roof" and "wall" are quite thick. When people dig caves, they choose places with hard soil. This thick and hard "wall" is not easy to transfer heat. Therefore, the top and wall of the cave can neither directly absorb heat from the atmosphere nor directly dissipate heat to the atmosphere, only the hole is in direct contact with the outside world. Therefore, the temperature change in the cave always lags behind the external temperature change, and the temperature difference changes little. "

In short, this information is very reasonable, but Bian Xiao is still dubious, because I have never lived in a cave after all, so I really don't know if it will be cold to live in a cave in winter. As far as the current climate of the earth is concerned, there used to be no snow in the south, but now it will snow first in the north. The climate is so chaotic that it is hard to say whether living in a cave will be cold.