Why is the temperature difference between day and night the biggest for thousands of years?

I can't find the answer to this on the Internet at present, but I think the reasons are as follows:

The sunny weather in autumn in China is known as "crisp in autumn", which increases the transparency of sunlight, so the sun is toxic during the day and the temperature rises rapidly; Clear skies also tend to dissipate heat into the universe. In places where there is no sun at night, the earth and air are easy to get cold, and the temperature drops rapidly, so it is particularly cold at night.

In short, it is the weakening of the atmosphere and clouds, which is also the reason for the large temperature difference between day and night of other planets except the earth.