What is the law of temperature change in a day?

The variation law of temperature in a day is mainly determined by the difference between the heat gained by the atmosphere (ground radiation) and the heat lost (atmospheric radiation).

The heat on the ground mainly comes from solar radiation, and the heat in the atmosphere (troposphere) comes directly from the ground.

(1) solar radiation

The strongest time is local time 12.

(2) Ground radiation

At 12 local time, the solar radiation heat gained on the ground is greater than the radiation heat lost on the ground, and the ground heat is excessive, and the ground temperature is still rising.

At about 1 in the afternoon, when the ground heat turns from surplus to deficit, the ground temperature is the highest in a day.

(3) Atmospheric temperature

At about 2 pm, the ground has transferred heat to the atmosphere through radiation and convection, and the temperature has reached the highest value.

Subsequently, the solar radiation continued to weaken, the ground heat continued to lose, the ground temperature continued to drop, and the temperature continued to drop. Before and after sunrise, when the surface heat changes from loss to excess, the surface temperature reaches the lowest value, and then the temperature also reaches the lowest value. Therefore, the lowest temperature always appears around sunrise.

This periodic daily temperature change is sometimes destroyed by the weather, such as thunderstorm weather or strong cold air activity, which can make the lowest temperature appear in the afternoon; It is cloudy in the morning and sunny at noon, so the highest temperature may appear in the afternoon, and vice versa.