Maximum and minimum temperatures.

The highest temperature does not appear at noon every day, but around 2 pm (14), and the lowest temperature appears around sunrise.

The hot and cold weather is mainly determined by the temperature, and the main factor affecting the temperature is determined by the intensity of solar radiation. However, solar photothermal is not the main reason for directly increasing the temperature. The direct absorption of sunlight by air is only about 14%, and about 43% of solar radiation is absorbed by the ground. When the ground absorbs the radiant heat of the sun, and then it is transmitted to the air through radiation, convection and other forms, this is the main reason for the temperature rise.

At noon 12, the solar altitude angle is the largest, the solar radiation intensity is the largest, and the surface unit area gets the most solar radiation, but the surface temperature does not reach the highest. First, after 12, although the solar radiation intensity began to decrease, it was still greater than the heat consumed by the ground, and the ground temperature continued to rise. Until noon 1 or so, the ground heat balance and ground temperature reached the highest.

A similar process is needed to transfer the heat absorbed by the ground to the atmosphere. After one o'clock in the afternoon, the heat transported from the ground to the atmosphere began to decrease, but it was still greater than the expenditure of atmospheric heat, so the atmospheric temperature continued to rise until about two o'clock in the afternoon, when the temperature reached the highest value.

After sunset, there was no solar radiation income, and the ground temperature and atmospheric temperature kept dropping until around sunrise the next day, when there was solar radiation income again, the temperature dropped to the lowest value in a day.