Definition of cyclone
A cyclone is a north (south) hemisphere with a large vortex in which the horizontal airflow in the atmosphere is reversed (cis) clockwise. At the same height, the air pressure at the center of the cyclone is lower than the surrounding temperature, also known as low pressure. It appears on the contour map as the low pressure zone surrounded by the closed isobar, and on the isobaric map is the low value zone enclosed by the closed contour. The cyclone is similar to a circle or an ellipse with a large size. The horizontal scale of small cyclones is several hundred kilometers, and the large ones can reach three or four thousand kilometers. It is a weather scale weather system. In the cyclone, the weather often changes drastically, which is the weather system that people care most about and the earliest research.