Qiu Jin's handwritten newspaper pictures.

Autumn is one of the four seasons. Traditionally, China takes "beginning of autumn" in 24 solar terms as the starting point of autumn. Entering autumn means that rainfall and humidity tend to decrease or decrease, and everything in nature begins to mature from lush. At present, the four seasons are usually divided according to the average temperature of modern scholar Zhang Baokun. The index is that the average temperature is below 10℃ in winter, above 22℃ in summer, and 10~22℃ in spring or autumn.

Autumn is a season of alternating hot and cold. Early autumn is still in the heat, but it hasn't come out yet. This is the hottest, wettest and sultry period of the year. After late autumn, it is sunny during the day, cool and dry at night, with large temperature difference between morning and evening, less rain and insufficient water. Therefore, autumn dryness has become the main feature of late autumn.

The four seasons in China are often divided according to the change of temperature, using the "average temperature" of modern scholar Zhang Baokun. According to the weather average temperature method, there are two main criteria to judge autumn. First, the average daily temperature for five consecutive days 10℃-22℃ can be regarded as autumn and become a "short mark"; Second, the moving average temperature of five consecutive groups is lower than 22℃. A set of moving average temperatures refers to the average temperature of the day plus the average temperature of the previous four days divided by 5 to get the moving average temperature of five days, which is a "sliding scale". Autumn divided by temperature means cool weather.

As the temperature gradually drops, the leaves of many deciduous perennial plants will gradually change color, wither and fall off, leaving only branches for winter. Panicum miliaceum will come to the end of his life, wither and die. Seasonal variation covers many aspects of climate characteristics, and it is not accurate to judge autumn only by temperature. The most obvious change in autumn is that the leaves of vegetation change from lush green to yellow, and the leaves begin to fall and the crops begin to mature.