How is sunny weather formed? What are the signs?

The pressure of the air is high or low. In the atmosphere, the higher the altitude, the thinner the air and the lower the air pressure. However, even if the height is the same, the air pressure varies from place to place. This is because the intensity of sunlight varies from place to place, and the temperature and density of air are also different. At the same height, the air pressure is different, some places have high air pressure, and some places have low air pressure. The place with low air pressure is called low air pressure area, also called cyclone area. The place with high air pressure is called high air pressure area, also called anticyclone area.

It is precisely because of the different air pressures in different places that the air moves horizontally, that is, the wind is generated.

Water flows from high to low. But the wind does not blow directly from the high pressure area to the low pressure area, but rotates around the low pressure area and the high pressure area. This is because the movement of air on the earth's surface is always influenced by the deviation of the earth's rotation. So in the northern hemisphere, the wind around the low pressure area rotates counterclockwise and scatters outward. We call the low pressure cyclone and the high pressure anticyclone precisely because they are constantly rotating. Cyclones are generally hundreds of kilometers in diameter, and anticyclones are generally thousands of kilometers in diameter. Some smaller and deeper cyclones are usually called eddies and eddies. The long and narrow low pressure belt connecting the large and low pressure areas is generally called low trough. Typhoon is a kind of tropical cyclone with strong development, and the wind around it rotates counterclockwise rapidly, becoming a huge vortex with a radius of several hundred kilometers. When it rotates, it runs forward, bringing storms and forming huge waves at sea.

The size of the wind is also affected by the air pressure. The greater the pressure difference in the horizontal direction, the faster the horizontal movement of air and the greater the wind force. If there is no difference in the air pressure in the horizontal direction within a certain range, the air will not move horizontally, which is called static wind. The wind revolves around the high and low pressure, and the wind direction is almost parallel to the pressure line around the high and low pressure. So, standing on the leeward side, in the northern hemisphere, the high pressure is on the right and the low pressure is on the left; In the southern hemisphere, the high pressure is on the left and the low pressure is on the right.

In the high pressure area, the air scatters outward while rotating, and the air at high altitude sinks to supplement it, which is called radiation. When the air pressure increases, the volume decreases, the temperature increases and the relative humidity decreases, which is called adiabatic warming. It can prevent the formation of clouds and make them dissipate, so it is always sunny in the high pressure area.