Today is the Great Cold | Let’s talk about the “N” sins of cold waves. How to deal with cold wave weather?

The Great Cold solar term is between the 39th and 49th days of the lunar calendar. At this time, cold waves frequently move southward. It is the coldest season of the year and also the period with the least rainfall. The atmospheric circulation is relatively stable, and the circulation adjustment cycle is about 20 days. During the circulation adjustment, there is often widespread rain and snow, strong winds and cooling, and cold waves may occur.

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01Whether it is a cold wave or not, the standards vary from place to place

Cold wave weather is one of the main weather phenomena in winter. When high pressure is generated in the north, the cold high pressure will invade southward along the northwest airflow behind the westerly trough and finally go out to sea. Cold wave weather can cause a sharp drop in temperature, and the temperature drop is large, sometimes reaching more than 10°C in one day. The passage of cold waves is often accompanied by strong winds, usually with wind speeds of level 5 to 6. When the cold air is strong or the ground low pressure develops strongly, the wind speed can reach level 7 to 8, and the instantaneous wind speed will be even greater. Cold wave weather can also bring rain and snow, especially in northern regions, where snowfall or sleet may occur.

Staff from the Shiyan Train Operation Section of China Railway Wuhan Bureau Group Company spread salt to clear snow in front of Shiyan East Station. Xinhua News Agency (Photo by Jiang Rongyang)

Due to differences in climate conditions, geographical locations, and socioeconomic conditions, cold wave standards may also vary. The national standard for cold waves: After a cold front passes through a certain area , if the daily minimum temperature drops by 8°C or more within 24 hours , or by 10°C or more within 48 hours , or by 12°C or more within 72 hours , and the daily minimum temperature in the area drops to 4°C or below , a cold wave is considered to have occurred.

Due to the vast territory of my country and the great differences in climate between the south and the north, there are certain differences in the definition standards of cold wave weather in different places.

The cold wave standard used in the north is a temperature drop of more than 10°C in 24 hours, or a temperature drop of more than 12°C in 48 hours, with the lowest temperature below 4°C;

The cold wave standard used in the south is a temperature drop of more than 8°C in 24 hours, or a temperature drop of more than 10°C in 48 hours, while the minimum temperature is below 5°C.

02 Detailed discussion of the “N” sins of cold waves

▶Wrecking agriculture

The drastic drop in temperature brought by the cold wave often exceeds the cold tolerance of crops, causing them to suffer frost damage, wither or die completely. The accompanying strong winds, rain and snow may cause devastating blows to agricultural facilities, such as greenhouses and greenhouses, which may collapse due to snow and strong winds.

▶Interruption of power supply and communication

The freezing rain caused by the cold wave will cause rime to accumulate on power transmission and communication lines. The lines will shrink due to the cold, and the vibrations caused by the wind and the weight of the rime may cause the lines to be broken, resulting in power supply and communication interruptions.

▶Disrupt traffic

The cold wave caused low visibility, ice on the ground and snow on the road, posing a great threat to road and rail traffic safety. Strong winds may cause trains to derail or even overturn, especially in some areas with strong winds such as Xinjiang's "100-mile wind zone" and "30-mile wind zone". Strong winds make it easy for aircraft to have tire ruptures and landing gear breaks during takeoff and landing.

▶Other disasters

Strong winds may also create storm surges at sea, forming huge waves several meters high, which can have a devastating impact on ships at sea. Therefore, shipping is often forced to stop and ships have to enter the port to avoid danger.

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▶Cause disease

Cold wave weather may cause coronary heart disease, cor pulmonale, stroke, myocardial infarction, angina pectoris and other diseases, and sometimes make the patient's condition worse. Strong wind and cold weather can easily cause colds, tracheitis, asthma and other diseases.

03Response to cold wave weather

Cold wave weather is a common weather phenomenon in winter. Due to its different intensities, the scope and degree of impact are also different. We should actively respond to this to minimize the impact and disasters caused by this weather.

◆The meteorological department should pay close attention to weather changes and promptly release cold wave weather forecasts and warning information through various means.

◆Relevant departments should strengthen emergency duty and information reporting, formulate emergency plans, and ensure that personnel and materials are in place.

Agricultural emergencies

◆Carry out tillage, weeding, soil cultivation, and irrigation and drainage in a timely manner to keep the soil moist.

◆Apply more phosphorus and potassium fertilizers, foliar fertilizers or heat-based farm manures such as wood ash to promote plant growth and enhance the ability to resist cold.

◆Before frost comes, use straw, stalks, ground film, etc. to cover the ground to increase the ground temperature.

◆Vegetable or flower greenhouses can be covered with straw mats, double-layer films and other insulation materials to increase the temperature inside the greenhouse.

Farmers are reinforcing greenhouses at a tomato planting base in Dalin Village, Shifan Street, Yueqing City, Zhejiang Province, to prepare for the cold wave (drone photo). Xinhua News Agency (Photo by Cai Kuanyuan)

◆Spray antifreeze before the temperature drops to form a solidified protective film on the surface of the plant leaves to enhance the plant's cold resistance.

◆Strengthen the monitoring of ships in waters affected by cold waves and strong winds, and promptly remind relevant water-related units and construction companies to make preparations for prevention and control.

◆Pay attention to the weather warnings issued by the traffic management department and drive according to the prompts.

Travel safety

◆Try to reduce driving, choose walking or public transportation, and pay attention to traffic safety.

◆If you need to drive, you should reduce your speed, keep a safe distance between vehicles, drive carefully, and avoid sudden acceleration, sudden braking, and emergency turns.

◆Stock up on anti-skid chains, hardwood blocks, used cardboard boxes and other items in advance in case of emergency situations such as tire slippage on icy or snowy roads.

◆Strengthen inspection and maintenance of key roads and bridges, and clear snow and ice in a timely manner.

Power and Network

◆Strengthen the inspection and maintenance of power grid equipment to ensure the safe and stable operation of the power grid.

◆Reasonably arrange the operation mode of the power grid, balance the power and electricity, and ensure the power supply.

◆Strengthen network early warning monitoring to ensure the safe and stable operation of the network in severe weather.

Health

◆Add clothes in time, paying special attention to keeping the head, hands and feet warm.

◆Avoid prolonged exposure to cold environments and change sweaty clothes promptly after exercise.

◆Keep indoor air circulating to prevent carbon monoxide poisoning, especially in homes using coal stoves for heating.

◆Special groups such as the elderly, children, and patients with cardiovascular and cerebrovascular diseases should pay special attention to keeping warm and regularly monitor health indicators such as blood pressure and blood sugar.

◆Keep a good mood, participate in more indoor activities, and increase sunshine time.

Author: Wang Yuanhong, Senior Weather and Climate Engineer

Produced by: Science Popularization China