Great Heat is the twelfth solar term in the Chinese lunar calendar. On July 23 or 24 every year, the sun reaches 120° of ecliptic longitude. This is around the time of the midsummer period, which is the hottest period of the year in most parts of China.

The climate characteristics are: "Bou Zhi C is the Great Heat, and the weather at this time is much more severe than the Little Heat, so it is called the Great Heat." The Great Heat is around the mid-summer period, which is the hottest solar term of the year. In many areas of our country, high temperatures of 40 degrees Celsius often occur. In this unbearably hot season, heatstroke prevention and cooling cannot be ignored.

The Great Summer Festival coincides with the "Three Volts", which is the period with the most sunshine and the highest temperature in our country. Most areas of the country are drought and have little rain, and the temperature in many areas reaches above 35 degrees. It is commonly known as the "Three Furnaces" "It's also the most prosperous.

In areas such as the middle and lower reaches of the Yangtze River north of South my country, such as Jiangsu, Zhejiang, and Jiangxi, it is a hot and rainy season, and the raindrops are like gold. In the western region of South my country, although high temperatures occur most frequently, rainfall is the most abundant and thunderstorms are the most common. This is the season with the most thunderstorms.

Extended information:

High temperatures during the Great Summer are normal climate phenomena. At this time, if there is insufficient light, the growth of temperature-loving crops such as rice and cotton will be affected. However, long periods of continuous high temperature weather are very detrimental to the growth of crops such as rice.

There is a farmer's proverb in the middle and lower reaches of the Yangtze River: "Five days without rain will cause a small drought, ten days without rain will cause a major drought, and a month without rain will cause smoke." It can be seen that high temperature and low rainfall are the conditions that promote the formation of drought. The harm of sustained large-scale high temperature and drought in drought-prone areas is sometimes greater than local floods. In addition to the need for drought prevention in the middle and lower reaches of the Yangtze River, drought prevention is also needed in Shaanxi-Gansu-Ningxia, eastern Southwest China, especially eastern Sichuan, and Chongqing.

Actually, drought does not occur every year. If the subtropical high pressure is weak in midsummer and there are one or two typhoons raining in the south or in the middle and lower reaches of the Yangtze River, or there are some thundershowers from time to time, there will be no widespread drought. .

Farming

(1) Harvesting of early rice and transplanting of late rice

“The crops will turn yellow day and night during the Great Heat”, which is a timely event for areas where double-cropping rice is grown in China. Harvesting early rice can not only reduce the damage caused by wind and rain in the later period and ensure a bumper harvest, but also allow the rice to be planted at the right time to ensure a sufficient growing period. Arrangements should be made flexibly according to weather changes. Cut more on sunny days and plant more on cloudy days. Planting should be completed in two nights before the end of July, and no later than the beginning of autumn at the latest.

(2) Irrigation

The leaf area of ??cotton reaches its maximum value during the flowering and boll stage, which is the peak period of water demand. The field soil moisture is required to account for 70-80% of the field water capacity. It is best if it is less than 60%, it will be affected by drought and cause flowers and bells to fall, so it must be irrigated immediately.

It should be noted that irrigation should not be carried out at noon when the temperature is high, so as to avoid excessive changes in soil temperature and aggravating the shedding of buds. The flowering and pod setting of soybeans is also the critical period of water demand, and they are very sensitive to water shortage. A farmer's proverb says: "Soybeans bloom, and shrimps are caught in the ditch." If there is a drought, you should water it in time.

(3) Drought resistance

In the hot summer, water evaporates very quickly, especially in the middle and lower reaches of the Yangtze River, which is in the drought period. The vigorously growing crops have more urgent requirements for water. It is really "The rain in a small summer is like silver, and the rain in a big summer is like gold." Summer corn in the Huanghuai Plain has generally been jointed and booted and is about to tassel, which is the most critical period for yield formation. The danger of "stuck neck drought" must be strictly guarded against.

Reference: Baidu Encyclopedia - Great Heat