What Is an Anticyclone?

Anticyclone refers to the horizontal air vortex whose central pressure is higher than the surrounding air pressure. It is also the high pressure in the air pressure system. In the northern hemisphere anticyclones, the horizontal air currents in the lower layers diverge outward in a clockwise direction, while the southern hemisphere anticyclones diverge outward in a counterclockwise direction. The horizontal scale of anticyclones is larger than that of cyclones. For example, the Mongolia-Siberian high in winter occupies 1/4 of the Eurasian continent. The central air pressure of each anticyclone is generally about 1020 to 1060 hPa, and the highest air pressure record reaches 1101.6 hPa. The wind speed in the anticyclone is small, the maximum wind speed on the ground is only 20-30 m / s, and the wind force in the central area is weak. Under the control of anticyclone, the weather was mostly sunny.

Anticyclones are horizontal air vortices that occupy three degrees of space and whose central pressure is higher than the surrounding air pressure. They are also called high pressures. The names of cyclones and anti-cyclones are from the field of high airflow, while the names of high pressure and low pressure are from the field of air pressure. The size of cyclones and anti-cyclones is measured by the range of the outermost closed isobaric line on the ground map. The horizontal scale of a cyclone is generally 1000km, the larger one can reach 2000-3000km, and the smaller one can only be 200-300km. The horizontal scale of anticyclones is generally much larger than that of cyclones. The intensity of cyclones and anticyclones can reach thousands of kilometers when they are strong. The strength of the cyclones is represented by the central pressure value. The higher the central pressure value, the greater the intensity. Generally, the air pressure at the center of the surface cyclone is 1010-970 hPa, and the strong development can be lower than 935 hPa. It has been as low as 920 hPa on the ocean. The surface anti-cyclone center air pressure value is generally 1020-1030hPa, and the strong development can reach 1079.1hPa. In the northern hemisphere, air rotates counterclockwise around the center in a cyclone, and air rotates clockwise around the center in an anticyclone. In the southern hemisphere, air flows in opposite directions. Cyclones are divided into temperate cyclones and tropical cyclones according to where they occur, and anticyclones are divided into polar anticyclones, temperate anticyclones, and subtropical anticyclones. Cyclones and anticyclones are two important types of weather systems that cause weather changes. Temperate cyclones and anti-cyclones occur in the middle and high latitudes and accompany high-altitude fronts. Their occurrence, development and movement are closely related to high-altitude weather systems. [1]
The path of anticyclone is less clear than that of cyclone. Due to the south and north latitudes of 25 ° -30 °, the air sinks and diffuses near the ground to form anti-gas.

Anticyclone cold wave

The cold wave is a kind of catastrophic weather in winter, and the masses are accustomed to calling the cold wave a cold current. The so-called cold wave is a weather process in which the cold air from the north invaded our country to the south on a large scale, causing a large-scale sharp cooling and northerly winds. The cold wave usually occurs in the late autumn, winter and early spring. China's meteorological department stipulates that the cooling temperature caused by the invasion of cold air reaches above 10 ° C in one day and the minimum temperature is below 5 ° C. This cold air burst process is called a cold wave process. It can be seen that not every time the cold air goes south is called a cold wave.
In the Arctic, due to the weak sunlight, the ground and the atmosphere receive less heat, and it is snowy all year round. In winter, the position of direct sunlight crosses the equator and reaches the southern hemisphere. The coldness in the Arctic region has increased, and the range has expanded. The temperature is generally below -40 ° C-50 ° C. Large-scale cold air masses gather to a certain extent, and under the action of appropriate high-altitude atmospheric circulation, they will invade southward on a large scale and form cold wave weather.
China is located in the southeast of Eurasia. Heading north from our country is Mongolia and Russia's Siberia. Siberia is a place with a very cold climate. Going further north, you will reach the northernmost part of the earth, the Arctic. It is colder than Siberia and has a longer cold period. The cold wave that affected our country came from those places.
Located in the high latitudes of the Arctic region and the Siberian and Mongolian plateaus, it receives oblique rays of sunlight all year round, and the ground receives very little heat from sunlight. Especially in winter, the sun's rays move south, and the angle of sunlight in the northern hemisphere is getting smaller and smaller. Therefore, the amount of sunlight absorbed by the ground is getting less and less, and the temperature of the ground surface becomes very low. In the Arctic Ocean in winter, the temperature is often below -20 ° C, and the lowest can be -60 ° C--70 ° C. The average temperature in January is usually below -40 ° C.
Because the temperature in the Arctic and Siberia is very low, the density of the atmosphere will increase greatly, and the air will shrink and sink, increasing the pressure. In this way, a powerful, deep and wide cold high-pressure air mass will be formed. When this cold high-pressure force intensifies to a certain extent, it will flow like a tide that breaks the embankment, and it will surge into our country violently. This is the cold wave.
After each cold wave erupts, the cold air in Siberia decreases by a part and the air pressure decreases. But after a period of time, cold air gathered and accumulated again, giving birth to a new cold wave.

Anticyclone cold wave invasion path

According to statistics, about 95% of the cold air passes through central Siberia (70 ° ~ 90 ° E, 43 ° ~ 65 ° N) and accumulates there. This area is called the key area of cold wave. There are four main ways to invade our country from key areas:
(1) Cold air from Northwest Road (Middle Road) passes from key areas through Mongolia to south of China's Hetao, and directly to the middle and lower reaches of the Yangtze River and Jiangnan. The cold air that follows this path is mainly caused by northerly winds and cooling in the north of the Yangtze River. After reaching the south of the Yangtze River, it may develop rain and snow weather due to the active fluctuations in the southern front.
(2) The cold air from Donglu Road passes from Mongolia to northern China through key areas. While the main force of cold air continues to move eastward, the cold air at low altitude folds to the southwest, invades North China via the Bohai Sea, and then reaches the two lake basins from the lower Yellow River to the south . The cold air that follows this path often causes strong northeast winds in the Bohai Sea, the Yellow Sea, the lower Yellow River, and the lower Yangtze River, recirculation in North China and East China, lower temperatures, and continuous rain and snow.
(3) The cold air on the west road passes from Xinjiang, Qinghai, and the southeastern side of the Tibet Plateau from the key area to the south. It has a great impact on the northwest, southwest, and south of China, but the temperature drop is not large. When the wave fronts are superimposed on the same phase, they can also cause significant cooling.
(4) The cold air on the east road and the west road on the east road goes south from the lower reaches of Hetao, and the cold air on the west road goes from the southeast of Qinghai. Snowy weather, and then the two cold air merged southward, with strong winds and significant cooling. [2]

Impact of Anticyclone Cold Wave

The high winds and cooling weather usually brought by the cold wave and strong cold air are the major catastrophic weather in winter in China. The cold tide is a great threat to coastal areas. For example, the cold tide from April 21 to 25, 1969, strong winds hit the Bohai Sea, the Yellow Sea, and other provinces such as Hebei, Shandong, and Henan. level. At this time is the astronomical tide. The cold tide caused the storm surge that is rare in Bohai Bay and Laizhou Bay for decades. In the area along the northeast coast of the mountain, the seawater rose by more than 3 meters, the seawall was destroyed by more than 50 kilometers, and the seawater was flooded by 30-40 kilometers.
Rain and snow and freezing weather brought by the cold wave are not harmful to transportation. For example, a cold wave in late November 1987 caused many station turnouts under the jurisdiction of railway bureaus such as Harbin, Shenyang, Beijing, and Urumqi to freeze, the tracks were buried in snow, communication signals failed, and train operation was blocked. After rain and snow, roads became icy and slippery, and traffic accidents increased significantly. The cold wave is very harmful to human health. Cold and windy weather can easily cause colds, bronchitis, coronary heart disease, pulmonary heart disease, stroke, asthma, myocardial infarction, angina pectoris, migraine and other diseases, and sometimes worsen the patient's condition.
The cold and windy weather brought by the cold wave has a great impact on the transportation of ships. In order to protect the safety of ships, crews and passengers, some precautionary measures should be taken; heavy winds and snow can reduce visibility, and at the same time make it difficult for the ship to handle and cause serious deflection. And shifts pose a threat to the safety of passing ships. To this end, ships should choose a safe place to moor the wind in time according to their wind resistance, display signals, sound the numbers, and adopt various safety measures in accordance with regulations. They should clean snow and ice, decks, aisles, and springboards in time. Non-slip mats to avoid accidents at work; bandages should be wrapped with warming materials and drained of excess water. Prevent icing in the tube to swell the tube wall. In northern rivers, ships should be prepared for docking in winter to prevent the ship from freezing in the channel. [3]
It is rarely mentioned that the cold wave also has beneficial effects. Geographical research and analysis show that cold waves help heat exchange on the surface of the earth. With increasing latitude, the earth's receiving solar radiation energy gradually weakens, so the earth forms tropical, temperate and cold zones. The cold wave brings a lot of cold air to the tropics, which enables large-scale heat exchange on the ground, which is very helpful to maintain the balance of nature's ecology and keep the species flourishing.
Meteorologists believe that the cold wave is the guarantee of good weather. Affected by the monsoon, China has a dry climate in winter and a dry season. However, whenever the cold wave invades the south, it often brings a large range of rain and snow weather, which alleviates the winter drought and benefits the crops. Why can the agricultural saying "Ruixue Zhaofengnian" be passed down through the ages? This is because the nitrogen content in snow water is high, which is more than five times that of ordinary water, which can greatly increase the nitrogen in the soil. Snow water can also accelerate the decomposition of soil organic matter, thereby increasing the organic fertilizer in the soil. Heavy snow covers winter crops and acts like a quilt for cold and heat preservation.
There is a saying, "It's not cold in winter and not rich in the coming year." This also has its scientific reason. Experts of crop disease and pest control believe that the low temperature brought by the cold wave is currently the most effective natural "insecticide", which can kill a large number of pests and germs that lurk in the soil for winter, or inhibit their breeding and reduce diseases and insect pests in the coming year. According to survey data from agricultural technology stations in various places, pesticides can save more than 60% in the winter when heavy snow falls.
The cold wave can also bring wind resources. Scientists believe that wind is a valuable source of power without pollution. Japan s Miyakojima wind power station, which attracts worldwide attention, has 1.5 times the power generation efficiency in the cold wave.

Anticyclone's sphere of influence

Its east-west length can be hundreds of kilometers to thousands of kilometers, but its thickness is generally only two to three kilometers. The speed of the cold wave is tens of thousands of meters per hour, which is about the speed of a train. There are roughly three routes affecting the cold wave in our country: one is the west road. This is the earliest and most frequent route affecting our country. The strong cold air set off from the North Pole, went west through Siberia, entered Xinjiang, China, and then invaded North China, Central Plains along the Hexi Corridor, and reached south China and even southwest. The second is the middle lane. The strong cold air from Lake Baikal in Siberia and the People's Republic of Mongolia passed through China's Inner Mongolia Autonomous Region and entered North China to the southeast coastal area. The third is East Road. Cold air travels southeast from northeast Siberia, sometimes through northeast China, sometimes through the Sea of Japan, the Korean Peninsula, and invades the eastern coast of China. The main force of the cold wave southward from this route is eastward, and the forces are generally not very strong and the number of times is not high.
Features Cold tide eruptions have different characteristics in different regional environments. In the northwest desert and the Loess Plateau, it is characterized by strong winds and less snow, which can easily cause sandstorms. Inner Mongolia grass principles are windy, snow blowing and low temperature weather. In North China and Huang-Huai regions, the cold wave often hits snowstorms. In the northeast, it is more violent winds and snow, and the snowfall is the highest in the country. It is often accompanied by bitter wind and rain in Jiangnan.
Cold wave prevention
Weather forecasts should be strengthened and accurate cold wave messages or alerts issued in advance
1. When the temperature drops suddenly, pay attention to keep your clothes warm, especially your hands and face.
2. Close the doors and windows and fasten the outdoor structures.
3. Beware of slipping and falling
4. Elderly and weak patients, especially those who are sensitive to temperature changes, such as cardiovascular patients and asthma patients, do not go out as much as possible.
5, pay attention to rest, do not be overly tired.
6. Beware of gas poisoning, especially for households using coal stoves for heating.

Anticyclone cyclone

In the northern (south) hemisphere, the horizontal airflow in the atmosphere is a large vortex rotating counterclockwise. In the northern hemisphere, it is skewed to the right and vice versa. At the same height, the pressure in the center of the cyclone is lower than the surrounding area, which is also called low pressure. Cyclones are approximately circular or elliptical in shape and differ in size. The horizontal scale of small cyclones is several hundred kilometers, and the large ones can reach three or four thousand kilometers. In cyclones, the weather often changes drastically. It is the weather system that people are most concerned about and the earliest to study. They are usually classified by the main area or thermal structure where cyclones are formed and active. It can be divided into temperate cyclones, tropical cyclones and polar cyclones according to regions; according to the thermal structure, it can be divided into cold cyclones and hot low pressures.
In the atmosphere, there are vortex motions similar to those in rivers. There are two types of clockwise and counterclockwise rotational motions: cyclones and anticyclones, which are large horizontal vortex motions in the atmosphere. Cyclone. In the northern hemisphere, air moves counterclockwise, and the center air pressure is the lowest, gradually increasing outward, and the air continuously flows into the center, forming an updraft, also called low pressure. Its diameter: tens of kilometers for small ones and thousands of kilometers for large ones. Rainy weather and strong winds often occur when cyclones are affected. There are a variety of large and small vortices in the atmosphere. Some of them rotate counterclockwise and some rotate clockwise. Among them, large horizontal vortices are called cyclones and anticyclones, which are low pressure and high pressure.

Anticyclone terminology

Cyclone: Cyclone is also called low pressure cyclone. Occupying three degrees of space, at the same height (isobaric surface), there is a closed isobaric (high) line, and the central pressure (height) is lower than the surrounding large vortex. In the northern hemisphere, the air rotates counterclockwise; in the southern hemisphere, its direction of rotation is the opposite anticyclone: anticyclone is also called high pressure. Cyclones and anticyclones are two aspects of a system.
JAC Cyclone: It refers to the cyclone in the JAC region.
Northeast cyclone: also known as the northeast depression. Cyclone in Northeast China. It is one of the important weather systems affecting our country.
Frontal cyclones: also known as extreme frontal cyclones, wave cyclones, and barotropic cyclones. Strong baroclinic cyclones occur on the fluctuations in the development of temperate polar fronts. China has developed frontal cyclones from fronts entering low pressure troughs, shallow low pressures or typhoons.
Cold vortex: Abbreviation for cold low vortex. The center is cooler than the surrounding vortex, and its intensity increases with height.
Northeast cold vortex: A large-scale cold vortex that is active in or near northeast China. It is a deep system capable of sustaining 3-4 days or more.
Southwest Low Vortex: Also referred to as the Southwest Vortex. Under the combined action of the special terrain and certain circulations in the Tibet Plateau and the southwestern region, a shallow and low vortex generated in the low altitudes of southwestern China.


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