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Intriguing Characteristics of a Warm Front Explained With Diagram

Characteristics of a Warm Front with Diagram
A hot air mass replacing a cold air mass results in the formation of a warm front. To understand this phenomenon better, let's take a look at some important facts about a warm front.
Anup Patwardhan
Last Updated: Dec 09, 2017
Did You Know?
A 'cold front' and 'stationary front' are two other types of air fronts besides a warm front.
An air mass is essentially made up of water vapor, and it is defined by its temperature. Air masses are of two types - warm and cold. These coming in contact with each other leads to the formation of a weather front. Winds are caused due to rotation of the Earth. These result in different air masses flowing around one another, instead of directly going through one another. Thus, the air masses come in contact with one another.
How Does a Warm Front Form
Warm front
Labeled diagram of a warm front
When two air masses come in contact with one another, and the warm air mass replaces the cold air mass, it results in the formation of a warm front. Make no mistake, the warm air mass does not displace, but simply replaces the cold air mass. This is because, the warm air mass is light and warm. Instead, it moves over to the upper boundary of the opposing air mass. Here, the air mass cools as well as expands, so does the vapor content that it holds, and it leads to the formation of clouds.
Warm Front Symbol
Warm front symbol
Representation of a warm front on the weather map
The symbol of a warm front is as shown below. The actual front is denoted by a solid line, which has semicircles or scallops on it at regular intervals. The face of these scallops is towards the cold air, and in direction of motion of a warm front, which is from warm air mass to cold air mass. In colored diagrams, a warm front is denoted by a solid red line.
Characteristics of a Warm Front
The direction of wind changes from southeast, before a warm front passes, to southwest, after the passing of the front. This is accompanied by warmer temperatures, a slight rise that is followed by a fall in the pressure. There is also some improvement in the visibility. The dew point also rises, after which, it becomes steady. Usually, there is no change in the precipitation along a warm front, while at times, there is a drizzle.
The change in cold and dry air to warm and moist air is one of the signs of an approaching air front. When traveling from one place to another, there can be a sudden rise in the temperature, which can be attributed to the presence of a warm front nearby.

In a cold front, a cold air mass replaces a warm air mass, while a stationary front is formed when both the air masses, warm and cold, are too weak to replace one another.