What is a high-pressure system and a low-pressure system in geography?

Anti-cyclone refers to the horizontal air vortex with the central air pressure higher than the surrounding air pressure, and it is also the high pressure in the air pressure system.

Impact:? When the air in the anticyclone spreads around, it forms a downward airflow. Therefore, when the anticyclone controls the city, the weather is generally better. It is sunny and cold in winter, sunny and hot in summer, windy in spring and autumn and crisp in autumn.

2, low pressure system

Cyclone refers to the northern (southern) hemisphere, and the horizontal airflow in the atmosphere is a large vortex rotating counterclockwise (clockwise). At the same height, the air pressure in the center of the cyclone is lower than that around it, which is also called low pressure.

Impact: As air flows into the cyclone center from all directions, the central airflow is forced to rise and condense into rain. Therefore, when cyclones cross the border, the cloud cover increases, and rainy weather often occurs, that is, cyclone rain. In the frontal weather system, whether it is a cold front or a warm front, the warm air mass above the frontal surface rises along the frontal surface, which will form cloudy and precipitation weather, that is, frontal rain.

When the two systems combine to form a frontal cyclone, it will converge into a stronger updraft, and the weather will change more violently, often causing clouds, rain and even heavy rain, thunderstorms and windy weather.

Extended data

study history

As early as 65438+60s, people discovered and began to study the structure and activity law of extratropical cyclones. In 1863, fitzroy, the first director of the British Met Office, put forward the surface airflow structure in temperate cyclone and anticyclone areas for the first time according to the opinions of H.W. Dovo and the data accumulated during the voyage.

In 1878, R. Aybak Longby gave a cyclone weather chart model combining pressure field, which combined pressure situation with weather. At the beginning of the 20th century, N Shaw, a British meteorologist, put forward a cyclone model which reflected the characteristics of airflow shear and storm in cyclones, and linked the precipitation distribution with airflow.

In 19 18 and 192 1, Norwegian scholars J. Pierre Knies and H. solberg put forward a new cyclone model and a cyclone life history model, which organically combined air mass, front, pressure field and weather distribution for the first time. These achievements of Norwegian school have been widely adopted by meteorological circles.

In 1930s, J. Pierre Knies and Finnish scholar E.H. Palmang did a lot of research on the three-dimensional structure of extratropical cyclones and fronts based on high-altitude sounding data. From the late 1940 s to the early 1950 s, Palmang further linked the cyclone family with long waves, and determined the relationship between temperate cyclones and long waves in the upper atmosphere.

These conclusions have been confirmed by satellite images in the 1960s. There are many methods to classify cyclones, usually according to the main areas or thermal structures where cyclones form and move. According to different regions, it can be divided into temperate cyclone, tropical cyclone and polar cyclone vortex (see polar meteorology); According to the different thermal structures, it can be divided into cold air swirl and hot low pressure.

Most temperate cyclones belong to frontal cyclones. Tropical cyclone and endemic thermal depression belong to warm depression. A strong cyclone vortex that occurs on the surface of tropical ocean is called a typhoon or hurricane when its central wind reaches a certain level. When it moves into the temperate zone, it will gradually have the characteristics of temperate cyclone.

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