Isobar in low pressure storage tank

The trough of low pressure is not an unclosed low pressure center, but an arm extension of low pressure (i.e. cyclone). Generally speaking, the line connecting the maximum bend on the isobar is either a trough of low pressure or a ridge of high pressure.

The long and narrow area extending from the low pressure area is called low pressure trough, and the air pressure in the trough is lower than that on both sides. On the weather map, the trough of low pressure generally extends from north to south. Any groove extending from south to north is called an inverted groove, and the groove extending from east to west is called a horizontal groove. The low pressure trough extending from north to south is generally in the westerly airflow, and the transverse trough is at the intersection of the northeast airflow and the northwest airflow. The inverted trough is in the easterly airflow. The line where the isobar bends the most is called the slot line. In the middle and lower troposphere, the airflow near the trough of low pressure appears in the form of convergent rise, so it is easy to produce cyclone and other weather systems near the trough of low pressure, and it is often accompanied by rain, snow, strong wind, cooling and other weather.