Why are caves warm in winter and cool in summer?

Actually, the so-called warm in winter and cool in summer is just a feeling, because caves can keep the indoor temperature constant more than other houses. They are warm in winter and cool in summer.

the surface temperature depends on the sun, that is, the direct sunlight is high, and the oblique sunlight is at the bottom, so it is cold in winter (the sun is oblique to the ground in winter) and hot in summer (the sun is relatively direct to the ground in summer), which also explains why it is different in spring, summer, autumn and winter.

It can keep a relatively constant temperature in the underground deep from the ground, and the caves are covered with thick soil, so it is very close to the underground temperature. When it is hot in summer, the underground temperature is lower than the surface temperature, so the cave is cool, and the ground is covered with snow in winter, while the underground temperature is much higher than the surface temperature, so the cave is much warmer.

Note:

To say that the cave has the feeling of being warm in winter and cool in summer does not mean that it can really make the temperature inside high in winter and low in summer. Just because of its special geographical location and special structure, there is a temperature difference between the inside of the cave and the outside, which gives people the feeling that it is warm in winter and cool in summer. Next, let's talk about the special geographical location selection and special structural structure of caves.

except for the door, the caves are all surrounded by thick soil. This thick soil layer can play a role in heat insulation. In summer, it is difficult for heat to be introduced into the cave, and in winter, it is difficult for heat in the cave to be emitted from it. This soil layer becomes a natural insulation layer. This is the same as the adobe house in our previous countryside.