Why is the temperature in Nianling Plain higher than that in mountainous areas?

First of all, it should be clear that the main heat source of the atmosphere is the long-wave radiation from the underlying surface.

Reasons for the small annual variation: In summer, due to the high altitude in mountainous areas, the atmosphere at the top of the mountain can get less energy from ground radiation, and the air is thin, so the temperature is low. In winter, high altitude areas are less affected by cold air, the air is thin and the cooling range is relatively small. In addition, the vegetation coverage rate in mountainous areas is usually high and the air mobility is good. Vegetation and atmosphere have stronger regulating effect on temperature than plain.

The reasons for the small diurnal range are as follows: firstly, influenced by the heat source in the troposphere, the main heat source in the troposphere comes directly from the underlying surface, so the temperature changes with the change of the underlying surface temperature. The farther away from the underlying surface, the lower the average temperature and the smaller the daily variation of temperature. Second, it is affected by the thermal conditions of mountain clouds. High altitude, low temperature and many clouds in the atmosphere. The solar radiation reflectivity is high during the day, and the atmospheric inverse radiation is strong at night, so the heat preservation effect is obvious. Third, the temperature in mountainous areas is influenced by the adjustment of the surrounding "free atmosphere". The mountainous area has high altitude and good air mobility. It is beneficial to communicate with the surrounding "free atmosphere". When the temperature rises in mountainous areas during the day, the "free atmosphere" at the same height plays a certain role in cooling down. At night, due to the thin atmosphere over the mountain area, weak thermal insulation and rapid temperature drop, the "free atmosphere" at the same height reduces the temperature drop in the mountain area, so the daily temperature variation in the mountain area is smaller than that in the nearby plain.