The weather system with the best visibility

The weather system with the best visibility is anticyclone.

Visibility refers to the clarity of the image displayed by the telescope. It depends on the degree of atmospheric turbulence. The twinkling of stars seen by naked eyes is generally considered to be caused by turbulence in the upper atmosphere. The poor definition of telescopes is often caused by turbulence in the lower atmosphere. Turbulence in each layer makes unstable areas with different densities appear in the atmosphere, which makes it impossible for light to pass through directly and the intensity remains unchanged. Measurement of celestial image quality affected by the disturbance of the earth's atmosphere.

Mainly used to describe the quality and angle size of point source images. Due to the influence of visibility, the limit resolution of ground telescope is only 1 s, which is far less than the diffraction limit of large telescope. In order to overcome its influence, adaptive optics technology has appeared in recent years. Visibility is a physical quantity, which is used to describe the degree to which astronomical observation objects appear blurred and flickering due to atmospheric turbulence.

Strictly speaking, visibility belongs to the category of atmospheric science research, and scientists who can engage in astronomical observation are very concerned, because its quality has a great influence on the quality of astronomical optical observation.

Meteorological characteristics of anticyclone;

Anti-cyclone is a horizontal air vortex with three-dimensional space, and the central air pressure is higher than that around it, which is also called high pressure. The names of cyclone and anticyclone come from the large airflow field, and the names of high pressure and low pressure come from the pressure field. The size of cyclone and anticyclone is measured by the range of the outermost closed isobar on the ground map. The horizontal scale of a cyclone is generally 1000km, the largest can reach 2000-3000km, and the smallest is only 200-300 km.

The horizontal scale of anticyclone is generally much larger than that of cyclone. When it is strong, it can reach several Qian Qian meters. The intensity of cyclone and anticyclone is expressed by the central pressure value. The lower the air pressure in the cyclone center, the greater the intensity. The higher the air pressure in the anticyclone center, the greater the intensity. Generally, the air pressure at the center of surface cyclone is10/0-970 hectopascals, which is lower than 935 hectopascals in strong development and as low as 920 hectopascals in the ocean.

Generally, the air pressure at the center of the surface anticyclone is 1020- 1030 hectopascals, and the strong anticyclone can reach 1079. 1 hectopascals. In the northern hemisphere, the air in cyclone rotates counterclockwise around the center, and the air in anticyclone rotates clockwise around the center. In the southern hemisphere, the airflow is the opposite. Cyclones are divided into temperate cyclones and tropical cyclones according to the occurrence area, and anticyclones are divided into polar anticyclones, temperate anticyclones and subtropical anticyclones.

Cyclone and anticyclone are two important weather systems that cause weather changes. Temperate cyclones and anticyclones occur in middle and high latitudes, accompanied by high-altitude front areas. Their occurrence, development and movement are closely related to the upper-air weather system.