What does the trough mean? What exactly does the trough mean?

1, and the low-pressure trough refers to a long and narrow area extending from the low-pressure area.

2. The trough of low pressure refers to the connecting line between the points with the highest cyclone curvature and the lowest pressure (or potential height) on the medium pressure (high) line. It is the area with the strongest horizontal convergence of airflow in the low pressure trough. Usually, the weather changes obviously near the trough line. For example, in the westerly belt, the southerly wind often blows in front of the trough line, and there is an upward movement. A large amount of water vapor can form clouds and precipitation.