Time division of day and night

The daytime refers to 12 hours from 8 am to 20 pm, and the night refers to 12 hours from 20 am to 8 am the next day.

In the weather forecast, "daytime" also refers to 8: 00 to 20: 00, and "night" also refers to 20: 00 to 08: 00. At present, the meteorological department has launched a three-hour weather forecast, and will gradually launch an hourly weather forecast in the future, so that the public can know the weather situation at each time point more accurately.

The reason why the days get shorter.

In September every year, the speed of shortening the day is the most obvious. Because the earth rotates obliquely and revolves around the sun at the same time, the direct point of the sun to the earth moves southward day by day from the summer solstice; At the autumnal equinox, point-blank at the equator; After the autumnal equinox, the direct point of the sun moves to the south of the equator, so the sunlight distributed to the northern hemisphere decreases day by day, so the days in the northern hemisphere shorten day by day.

In high latitudes, the changes of short days and long nights are more obvious. Therefore, Zhao Zhi Heng has chosen several representative cities: in September, the daytime will be reduced by 92 minutes in Harbin, 80 minutes in Shenyang, 75 minutes in Beijing, 54 minutes in Shanghai and 40 minutes in Xiamen.