Which cities in China enter winter earlier? For example, after entering August, which areas were the first to catch a cold after September?
In ancient times, the division of the four seasons in China began with Lichun, Changxia, beginning of autumn and beginning of winter. Astronomically speaking, the four seasons start from the vernal equinox, summer solstice, autumn equinox and winter solstice. Now March to May is generally spring, June to August is summer, September to 165438+ 10 is autumn, and June to February is winter. In China, climate is often divided into four seasons based on climate temperature: the average climate temperature is 22℃ in summer, lower than 10℃ in winter and between 10℃ and -20℃ in spring and autumn. The climate varies from place to place, so the length of the four seasons is also different.
Winter is the coldest season in the whole year, and June is 5438+ 10. The average temperature in more than two thirds of the country is below 0℃. The 0℃ isotherm in the L-month isotherm extends westward to the southeast edge of the Qinghai-Tibet Plateau through the Huaihe River and Qinling Mountains, and then to Linzhi and Delangzong in Tibet through the Hengduan Mountains. In the area north of this line, rivers are generally frozen. The average temperature in the northeast, northwest and most parts of the Qinghai-Tibet Plateau 1 month is below-10℃, among which Daxing 'anling, Xiaoxing 'anling, Altai Mountain and northern Tibet Plateau are still below -20℃, and the northern part of Daxing 'anling is below -30℃. The extreme minimum temperature in Mohe Town, the "Arctic Village" in China, reaches 52.3℃. In the area south of 0℃ isotherm, the river has no freezing period, only snow drift. The area south of Nanling is above 10℃. Taiwan Province Province, the southern tip of Hainan Island and the South China Sea Islands are all above 20℃. In a word, the distribution law of winter temperature in China is from south to north, and gradually decreases with the increase of latitude, and the temperature difference between north and south is very large, reaching more than 50℃. On average, the temperature drops by 65438 0.5℃ for every latitude added to the north.
In winter, Mongolian high pressure forms, and at the same time, low pressure appears on the ocean, resulting in the situation that cold air flows eastward to the ocean. Therefore, at the turn of autumn and winter, at the turn of winter, the spring is chilly, and China is often hit by cold waves. The cold wave enters China in three ways: West Road, from Xinjiang to the east, through Hexi Corridor, and south along the east side of the Qinghai-Tibet Plateau, causing obvious cooling and large-scale rainy weather in the southwest and Jiangnan. The middle road enters China through Mongols, reaches the middle and lower reaches of the Yangtze River through Hetao and North China, and sometimes crosses Nanling to reach the Pearl River Basin. It is windy in the north of the Yangtze River and rainy and snowy in the south. East Road, starting from the northeast of Siberia or the Sea of Okhotsk, sometimes goes south through the northeast, crosses the Bohai Sea, the North China Plain to the two lakes basin, and sometimes goes south through the Sea of Japan, the Korean Peninsula and the Yellow Sea, affecting the southeast coast of China and causing long-term rain and snow. There is not much precipitation in winter, and China is generally dry and rainy. Only the middle and lower reaches of the Yangtze River and the south of the Yangtze River form a relatively stable precipitation zone.