Autumn is cool in the morning and evening, and hot at noon.

Why is the temperature difference between day and night large in autumn?

2006-9- 19

Jinan, September 18- After entering autumn, people can obviously feel the sudden widening of the temperature difference between day and night: during the day, especially around noon, the temperature is very high and people feel very hot, but the temperature is very low in the morning and evening, so people have to add clothes to keep out the cold. Why is the temperature difference between day and night so big in autumn?

The reporter learned from the Provincial Meteorological Observatory that the widening temperature difference between day and night in autumn is the climate characteristic of our province. Except for coastal areas, people can obviously feel the sharp increase of temperature difference between day and night in most areas of our province. Take Jinan as an example. On June 5438+02, the temperature was as high as 27.9℃ at 3 pm, while the actual temperature was only 16.6℃ at 6 am. Less than 10 hour, the temperature difference reaches 1 1.3℃.

Why does the temperature difference in autumn change like this? According to Zhang Shaolin, chief forecaster of the Provincial Meteorological Observatory, this is mainly related to frequent cold air activities and excessive radiation cooling in autumn. In autumn, the influence of the north wind is gradually strengthened, and cold air activities are more frequent. At the same time, there are few clouds in autumn, the sky is high and the clouds are light, the cold air flows faster and the temperature drops faster. Summer nights are different from autumn nights. Summer is not only high in temperature, but also cloudy and humid, just like a "cover" to delay the sudden drop of temperature.

It is reported that after autumn, the direct point of the sun moved southward from1132 ′ n to 5 57 ′ n. As the direct point of the sun moved southward, the daytime time shortened, the sunshine hours decreased, and the light and heat given to the northern hemisphere decreased. The weakening of solar radiation gradually reduces the heat gained by the ground during the day. But with the extension of the night, the heat radiated by the surface increases. Because the heat absorbed by the ground is less than the heat lost by the ground, the temperature tends to turn from high to low.