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Weather Fronts


When two dissimilar air masses clash, a border zone is known as a front that forms between them.

A front is not a normal two-dimensional border. A typical front is a long, narrow three-dimensional transition zone that stretches for many kilometres, if not tens of kilometres. Within this zone, the air's properties vary fast.

World War I

The Frontal Concept was developed during World War I by Norwegian meteorologists, and the term "front" was adopted because these scientists compared the clash of opposing air masses to a confrontation between opposing troops along a battlefront.

While some mixing occurs within the frontal zone as the more aggressive air mass advances at the expense of the other, the air masses retain their unique identities in the majority of cases where one is displaced by the other.

Types Of Fronts

Cold and Warm Fronts

Typically, the greatest noticeable distinction between air masses is their temperature. A cold front develops when an advancing cold air mass encounters and displaces warmer air, whereas a warm front develops when an advancing warm air mass encounters and displaces colder air.

In both circumstances, warm air surrounds one side of the front and chilly air surrounds the other, creating a rather abrupt temperature differential between the two. Additionally, air masses may have varying densities, humidity levels, wind patterns, and stability, resulting in a steep gradient through the front.

A front may remain stationary for a few hours or even a few days in some situations. However, a front is more frequently in constant motion.

Typically, one air mass displaces the other; as a result, the front advances in the direction specified by the more active air mass's movement. Whichever air mass advances, the warmer air always rises above the cooler.

The warmer, lighter air is eventually propelled aloft, while the cooler, denser air mass acts as a wedge, allowing the lifting to occur. Fronts 'lean' or slope upward from the surface, and it is along this slope that warmer air rises and cools adiabatically, forming clouds and frequently precipitation.

Horizontal & Vertical Fronts

Indeed, fronts are so slanted that they are far more resembling horizontal than vertical features. The slope of a normal front is approximately 1:150, which means that 150 kilometres from the front's surface position, the front is only 1 km above the earth.

Due to the extremely low angle of slope (less than 1°), the steepness depicted in the majority of front diagrams is substantially overstated.

When neither air mass displaces the other, or when a cold or warm front stalls,' they form a stationary front. Although generalisations about the weather along such a front are problematic, slowly ascending warm air frequently provides limited precipitation comparable to that accompanying a warm front.

On a weather map, stationary fronts are shown by a combination of warm and cold front symbols alternating on opposite sides of the line; cold air is represented by triangles, while warm air is represented by half circles.

When a cold front passes over a warm front, an occluded front forms. On a weather map, occluded fronts are indicated by a combination of warm and cold front symbols that alternate on the same side of the line.

Distribution Of Atmospheric Disturbances

The majority of atmospheric disturbances are characterised by unsettled and occasionally violent atmospheric conditions, which are referred to as storms. Certain types, on the other hand, provide calm, clear, tranquil weather that is the polar opposite of stormy. Several of these disruptions are caused by air mass contrasts or fronts, while others are caused by moving pressure cells.

The following are some of the most frequently encountered characteristics of atmospheric disturbances in general.

  • They are much smaller than the components of the general circulation, albeit their size varies considerably.

  • They are migratory.

  • They are transient in nature, lasting only a few minutes, hours, or days.

  • They generate weather conditions that are distinctive and relatively predictable.

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