What is a trough of low pressure and what is the weather like under its influence?

Influenced by geographical environment and seasonal changes, the distribution of ground pressure is generally uneven. The area where the air pressure is lower than the surrounding area is called the low pressure area. The long and narrow area extending from the low pressure area is called the low pressure trough. Man looks up, but water flows down. The air is in an area with low vitality. Different air streams converge on the low-pressure trough, the air is forced to rise, and the water vapor in the air condenses into clouds and rain. Thunderstorms are easier to form under appropriate conditions.

The trough of low pressure extends for hundreds of kilometers, but the bad weather mainly comes from convective cells with an area of tens of square kilometers, and the life history of these cells is only a few hours. Therefore, the effective time of rainstorm warning is usually not too long, unlike the tropical cyclone warning signal hanging all day. However, if the trough moves slowly, the area it occupies will often be affected by the newly developed convective cells, and the bad weather will continue and the rainstorm will continue.