Troughs and Ridges

What Are Troughs and Ridges?

Troughs and ridges are important terms you might hear when listening to a weather forecast. They can indicate what kind of weather a region might expect in the coming days. If you have ever wondered what troughs and ridges are exactly and how they relate to cyclones and anticyclones, then you are in the right place. You can learn all about the meaning and appearance of these essential weather indications. Be sure to share this article with your friends and family so that they can get a clearer idea of what troughs and ridges are too!

Troughs and Ridges Definition

Trough and ridges are commonly used weather terms, but what do they mean? Both features are important to examine when you are looking at a sea-level pressure map and trying to figure out the weather of a region. Troughs are elongated regions where there is low pressure, and they typically occur before a cold front. A trough is often an indicator of coming clouds, showers, or a shift in the direction of the wind.

Ridges, in weather terminology, are elongated regions of relatively high pressure. These result in dry conditions around them. They can also bring onshore winds resulting in coastal showers.

Troughs are known for bringing cool and cloudy weather with them, while ridges usually bring warmer and drier weather. This phenomenon is witnessed because the air in a high-pressure region or ridge compresses and gets warmer as it descends. When this happens, cloud formation is inhibited, so you are more likely to see sunny skies in high-pressure regions. The opposite is true when it comes to low-pressure areas.

Understanding ridges and troughs are important for weather forecasting. These high or low-pressure atmospheric regions develop further to form cyclones and anticyclones. The latter are spinning storms that occur around high-pressure systems. Cyclones, on the other hand, are closed cells with a low-pressure center.

A ridge is associated with the high pressure found in the middle of two low-pressure regions, and it forms the center of an anti-cyclone. You can expect the opposite to be true in the case of a trough. Cyclones are powerful storms, so the better these can be forecasted, the better.

What Is the Jet Stream and How Is It Related to Troughs and Ridges?

Jet streams are fast-flowing, narrow currents of air in the upper layers of the atmosphere. When significant temperature differences occur in the atmosphere, jet streams form. They are an east-ward moving current of air, which usually occurs at altitudes of about 5- 9 miles. This weather phenomenon affects the weather in various ways. A jet stream can change the wind and the pressure in that area.

Troughs and ridges are related to jet streams. A trough is a southward or downward dip in the wind current, while a ridge is a northward or upward hump in the jet stream. In the Northern hemisphere, the wind around a trough blows counterclockwise but clockwise around a ridge.

What Do Troughs and Ridges Look Like?

On a weather map or forecast, you can tell whether you have troughs or ridges. As the name suggests, a trough is U-shaped. Ridges, on the other hand, are similar to an upside-down U-shape. These features appear on a weather map as dashed lines. When there is a low-pressure region, symbolized by the letter L, there is a trough. For a high-pressure region around the dashed lines, symbolized by the letter H, there is a ridge.

The better you can identify troughs and ridges on a weather map, the easier it is to forecast the weather. If you listen to a weather forecast, these are terms you are likely to hear often. When you want to know what the likelihood of rain and snow might be in your area, then a pressure map is a great way to start.

What Are Upper-level Troughs and Upper-level Ridges?

An upper-level ridge is an elongated region of relatively high pressure. It is characterized by constant high altitude in the atmosphere. An upper-level ridge is often accompanied by dry and warm weather conditions.

Upper-level troughs are also known as upper troughs or high-level troughs. These troughs are more pronounced in the higher regions of the atmosphere compared with regular ones.

What Is Meant by Monsoon Trough?

A monsoon trough is where the wind patterns of the northern and southern hemispheres meet. On a weather map, it is depicted by a line where there is minimum sea-level pressure. The monsoon trough is located in the Western Pacific and forms a part of the Intertropical Convergence Zone.

The seasonal change in the direction of the prevailing winds in a region is known as a monsoon. Monsoons blow from the cold to the warmer regions and are responsible for weather changes in the wet and dry seasons in the tropical regions around the Indian Ocean. Monsoon troughs are important to understand because they affect the activities of monsoons.

What Is a Trough in Waves?

A trough can mean different things depending on the context. So, far you have learned about troughs in terms of weather and air pressure. In geological terms, a trough represents a narrow basin or structural depression, which is less steep than a trench. There can also be troughs when reference is being made to waves.

In water, troughs are the lowest point of the wave. The opposite of a wave trough is the peak or crest. The difference in height between the crest and the trough is known as wave height.

As you may know, there are different types of waves, including water waves, sound waves, and electromagnetic waves. Another way to describe a wave trough is the point where the maximum negative displacement of that the medium sinks to, be it water or air, for example.


There’s a lot to learn about how wind moves and what troughs and ridges are. Understanding pressure differences in the atmosphere can help you determine the upcoming weather conditions in a region. Feel free to share this guide on troughs and ridges to help your friends and family understand their origins!

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