There is strong rainfall in South China, so it is necessary to take precautions against strong convective weather.

From 08: 00 on the 22nd to 08: 00 on the 23rd, there were small to medium snow or sleet in southern Qinghai, northeastern Inner Mongolia, northern Heilongjiang and central and eastern Tibet. Among them, there is heavy snow in parts of southern Qinghai and northeastern Inner Mongolia, and there is heavy snow in the local area; There are small to moderate rains or showers in the eastern and northern parts of Southwest China, the eastern part of Northwest China, the central and eastern parts of Inner Mongolia, the central and western parts of Northeast China, and the northern and southern parts of South China. Among them, there are heavy rains and local heavy rains along the Yangtze River. There are 4 ~ 6 winds in eastern Xinjiang, Inner Mongolia, western Gansu and south-central Northeast China. Some areas in western Gansu, western Inner Mongolia and northern Ningxia have sand blowing or floating dust weather. There are 5 ~ 7 winds in the eastern sea area.

Meteorological science popularization

bitter cold

Frost refers to the sudden drop of temperature, and the surface temperature drops below 0℃, causing damage to crops and even death. The first frost in autumn is called the first frost, and the last frost in spring is called the last frost, which has a great influence on crops. Frost is a common agricultural meteorological disaster, which occurs in winter and spring, and is mostly caused by a cold wave going south and the temperature dropping below 0℃ in a short time. Still affected by the cold wave, the weather changed from cloudy to sunny that night, which was caused by strong radiation cooling on the ground. This is what people often say "adding insult to injury".

Frost defense:

1, irrigation method

Irrigation can increase the humidity of air near the ground, protect geothermal energy and raise the temperature (which can be increased by about 2℃). Because of the large heat capacity of water and slow cooling, the site temperature will not drop rapidly. For small area garden plants, water spraying can also be used. The method is to spray water on plants continuously with sprinkler irrigation equipment 1 hour before frost comes. Because the water temperature is higher than the air temperature, when the plants are cold, the water will release heat, and the water temperature is higher than the freezing point to prevent frost, and the effect is better.

2. Covering method

Cover plants with straw, wheat straw, plant ash, weeds, nylon, etc. It can not only prevent the attack of cold air from the outside, but also reduce the loss of geothermal energy, and generally increase the temperature 1-2℃. Some dwarf plants can also be buried in the soil to prevent freezing injury. This method can only prevent a small area of frost, and its advantage is that it takes a long time to prevent freezing.

Step 3 Fumigation

Use firewood, cow dung, sawn wood, waste engine oil, red phosphorus or other dust and smoke substances that can produce a lot of smoke, and ignite it half an hour before the frost comes or 1 hour. These smog can block the loss of heat on the ground, and the smog itself will also generate some heat, which can generally raise the air temperature near the ground by 1-2℃. However, this method has certain weather conditions, high cost and air pollution, and is not suitable for universal promotion. It is only suitable for preventing short-term frost and the use of rare trees and their nurseries.

4. Fertilization method

Applying organic fertilizer early before cold wave, especially using semi-decomposed organic fertilizer as base fertilizer, can improve soil structure and enhance its heat absorption and insulation performance. You can also use the semi-decomposed organic fertilizer to emit heat in the process of continuing to decompose, thus increasing the soil temperature. After winter, warm fertilizer can be used to cultivate forest plants, and the antifreeze effect is obvious. Warm fertilizers are commonly used, such as manure, compost and plant ash. This method is simple and feasible, but it should be applied 3-4 days before the frost comes to master the local climate law. After winter, lime water can be used to whitewash the trunks of trees and fruit trees to reduce heat dissipation.