A trough can refer to different things depending on the context. Here are some definitions:

• Meteorology: A trough is an elongated region of relatively low atmospheric pressure without a closed isobaric contour that would define it as a low-pressure area. Near-surface troughs sometimes mark a weather front associated with clouds, showers, and a wind direction shift. Upper-level troughs in the jet stream reflect cyclonic filaments of vorticity. Their motion induces upper-level wind divergence, lifting and cooling the air ahead (downstream) of the trough and helping to produce cloudy and rainy conditions there).

• Domestic or industrial container: A trough is a long, shallow, often V-shaped receptacle for the drinking water or feed of domestic animals. It can also refer to any of various domestic or industrial containers.

• Low point: A trough can also refer to a low point between two high points, as on a graph or record of activity.

In meteorology, troughs and ridges are important features in predicting the weather. Troughs are found near low-pressure areas while ridges are found near high pressure. Troughs are associated with colder air, low pressure aloft, and a less stable atmosphere, which tends to result in cooler and more unsettled weather conditions. On the other hand, ridges are associated with fair weather, and air under a ridge sinks, which is not conducive for the development of clouds and precipitation.