What's the difference between summer and autumn in America? For example, in the seasons of China, beginning of winter and Changchun, I can accurately distinguish summer from autumn.

American summer and autumn are divided into four seasons according to astronomical classification (that is, western classification). More emphasis is placed on the climatic significance of the four seasons, with the vernal equinox of the sun as the starting point of the four seasons, such as spring as the starting point and summer solstice as the end point. These four seasons are one and a half months later than the traditional four seasons in China.

In order to accurately reflect the actual climate situation in various places, climatology is often used to divide the four seasons, that is, the classification method of modern scholar Zhang Baokun and the average climate temperature are used to divide the four seasons. It is also stipulated that the period when the average climate temperature is greater than or equal to 22℃ is summer, the period when it is less than or equal to 10℃ is winter, and the period between 10℃ and 22℃ is spring or autumn.

According to this standard, the seasons in mid-latitude areas are consistent with the climate, while the temperature changes in low-latitude areas and near the polar regions are not obvious. At the same time, in mid-latitude areas, the length of each season is different. This is the four seasons. This method can be combined with the specific climate and agriculture in various places, so it is widely used.

The traditional method of dividing the four seasons in China takes four solar terms as the starting point of the four seasons, and bisection and two to one as the midpoint. For example, in spring, the starting point is beginning of spring, the solar line is 3 15, the spring is divided into the midpoint, the long summer is the end point, the solar line becomes 45, and the sun runs 90 on the ecliptic. This is a traditional and common method.