Why is the daily temperature difference at the top of the mountain smaller than that in the valley? Why is the daily range in mountainous areas smaller than that in piedmont plain?

Analysis of inverse radiation from illumination and atmosphere. First of all, it is affected by the heat source in the troposphere. The main heat source of troposphere atmosphere comes directly from the underlying surface, so the temperature changes with the underlying surface temperature. Affected by the temperature change of the underlying surface, the closer the troposphere atmosphere is to the underlying surface, the higher the average temperature and the greater the daily variation range of temperature. The farther away from the underlying surface, the lower the average temperature and the smaller the daily variation of temperature. Secondly, it is influenced by the thermal conditions of mountain clouds. Mount Tai has high altitude, low temperature, many clouds in the atmosphere and high reflectivity to solar radiation during the day. Thirdly, the temperature in mountainous areas is influenced by the adjustment of the surrounding "free atmosphere". Mountainous areas have high altitude and good air mobility, which is beneficial to exchange with the surrounding "free atmosphere". When the temperature rises in mountainous areas during the day, the "free atmosphere" at the same height has a certain cooling effect because of its low temperature and small daily variation. At night, due to the thin atmosphere over the mountain area, weak heat preservation and rapid cooling, the "free atmosphere" at the same height reduces the temperature drop in the mountain area, so the daily temperature difference in the mountain area is smaller than that in the nearby plain.