In meteorology, a cyclone is a type of tropical cyclone that rotates around a strong center of low atmospheric pressure. The cyclone is characterized by an inwardly rotating airflow that rotates around a low pressure zone. The largest low pressure system is the polar vortex and the largest scale extratropical cyclone . There are two types of cyclones, one is the small whirlwind common on the ground. This kind of whirlwind is changed rapidly when the air flows around the ground like trees, hills, buildings, etc., or when the air and the ground rub. The direction of its advancement will produce a vortex that moves with the airflow, causing no major harm to humans. The other is a large cyclone that occurs on the ocean and is called differently in different places.
When the air flows around an uneven place on the ground like trees, hills, buildings, etc., or when the air and the ground rub, it must change its direction of advancement rapidly, and then a vortex that moves with the airflow will occur. A whirlwind was blown up. However, this whirlwind is rare and small.
Cause of formation
The most important reason for the formation of a cyclone is that when a place is sun-heated, the air here will swell up, and some of the air will be squeezed up. After the sky, the temperature will gradually decrease and begin to flow around. Sink near the ground. At this time, the air in the heated area is reduced, the air pressure is also lowered, and the surrounding temperature is lower, the air density is larger, and the heated part of the air falls from the air, so the air increases and the air pressure increases significantly. In this way, the air will flow from the place where the air pressure is high to the place where the center pressure is low, just like the water flowing down. However, since the air is flowing on the earth, and the earth is constantly rotating from west to east, the air will be affected by the rotation of the earth during the flow, and will gradually shift to the right (the original north wind deflects into the northeast. The wind, the south wind deflects into a southwesterly wind, the west wind deflects into a northwest wind, and the east wind deflects into a southeast wind. The colder air that is blown from all around is then rotated around the heated low-pressure zone to become an air vortex that opposes the clockwise direction of the clock, which creates a cyclone.
The center of this whirlwind, because the warm air is rising, and the surrounding air is constantly rotating, it is easy to roll the dust, leaves, paper scraps, etc. on the ground into the air, and rotate with the flow of air. If the whirlwind is strong, sometimes some small animals on the ground, such as small snakes and small insects, will be rolled into the air and traveled with the wind in the dust.
Generally, the height of a small cyclone is not too large. When it is blocked by the friction of the ground or by houses, trees, etc., it gradually dissipates into an ordinary wind.
Some people may ask: Since the ground is heated, it is easy to start a whirlwind. That summer is hotter than spring. Why is there a little whirlwind and a spring whirlwind in summer? This is the reason why the summer weather is very hot, but the ground is green and the land is humid. There is not much difference, so there is very little whirlwind in summer. However, in the spring, the leaves have not yet fully extended, the grass has just sprouted, the cropland is a piece of light, and there is no obstruction everywhere, which is easy to heat, so that the temperature of the air on the ground changes greatly, it is easy to wind the wind. . 1
The cyclone can make the vertical mixing of heat, water vapor, etc. in the air, and make the vertical distribution of heat and water vapor in the air uniform