Fronts

Fronts can be defined as the transition regions or the transition zones between two different air masses. This region or zone of transition can range from 20-100 miles and the transitioning of the atmosphere from warm to cold or vice-versa can be felt distinctively.

The phenomenon when a cold air mass invades the territory of a hotter air mass. It is known as cold front and similarly when a hotter air mass invades into the region of cooler air it is known as warm front.

The zone of transition between the warmer and the cooler air masses is known as the frontal zone. The frontal zone, though being a region of transition, can sometimes be very sharp.

Types of fronts

The types of fronts are dependent on two main factors – the direction of the flow of the air masses and the characteristic of the air mass i.e, whether the air mass is cold or warm.

The types of fronts can be categorized into four categories:

1. Warm front
2. Cold front
3. Stationary front
4. Occluded front

1.Warm front

Warm front can be defined as the area of transition between a warm air mass and a cooler retreating air mass. Since the warmer air mass is always less dense than the cold air mass it tends to ride over the cooler air mass rather than displacing it.

Due to this phenomenon the warmer air mass travels at a much slower pace than the cold front. Also, the slope of the warm front is less steep than the cold front. Precipitation in the region of warm front is always much more even as compared to precipitation in the region of a cold front.

During the season of winter when a warm air mass passes over the region of almost sub-freezing temperatures it causes violent ice storms to develop almost 100 kms ahead of the region of the warm front.

2.Cold front

The cold front can be described as the region where the cold air mass moves rapidly towards the region of a warm air mass. Along the mid and higher latitudes the cold front shifts towards the equator in an eastward direction.

Rapid showers and thunderstorms are generally associated with the cold front. The cold front moves at a speed of almost 65 kms per hour and since it is heavier and denser than the warm front it cuts through the warm air mass and replaces it with cooler air.

In critical or extreme cases the presence of a cold front can cause the formation of tornadoes and extreme thunderstorms approximately 80 kms ahead of the cold front. The rainfall usually pauses after the front passes through.

3.Stationary front

The stationary front is also referred to as the quasi-stationary front which is formed when the two different air masses are moving towards one another at a speed less than 9 kms per hour.

When tracked on a map the quasi-stationary front can be depicted as stationary lines dividing the warm and cold air masses. A stationary front is formed when the warm and cold air masses slow down in a particular region before developing speed again.

At the stationary front the warm and cold air masses flow parallel to each other hence, they are depicted in the form of opposite spikes colliding with each other divided by a stationary line.

4.Occluded front

The condition of an occluded front develops when a cold front follows a warm front. Since the cold front moves faster than the warm front it is likely that the cold front would take over the warm front and lead to the formation of an occluded front.

The occluded fronts generally form in the low pressure regions. This front is associated with light precipitation since, in an occluded front the wind changes its directions. The passing of an occluded front paves way for drier air and clearer skies.

Frontogenesis and Frontolysis

Frontogenesis can be defined as the process of formation of fronts or frontal zones, in the condition of Frontogenesis the two different air masses collide into each other without converging into one another due to temperature differences.

And, the dispersion of a frontal zone can be termed as Frontolysis. In the phenomenon of frontolysis one of the dominant air masses collides against the other taking the space of the earlier air mass.

Coriolis Effect- The Coriolis Effect is a concept in physics which is also relevant in the condition of the formation of frontal zones. Due to the Coriolis Effect, objects such as air mass move in a curved manner rather than flowing in a straight direction.

Now, because of the Coriolis Effect the wind movement and the formation of fronts in the northern hemisphere occurs anti-clockwise and visa-versa in the southern hemisphere the movement of the air mass and the formation of the frontal zone occurs clockwise.

Conclusion

The collision of two different air masses causes the formation of a transition region between the two air masses which is commonly known as fronts. When the cold air mass invades the region of the warm air mass it is known as cold front, similarly when the warm air mass invades the region of cold air mass it is known as warm front.

Weather fronts are categorised into four types i.e warm front, cold front, stationary front and occluded front.