What is a Cold Front and How Does it Form?

What is cold front
A cold front is the leading edge of the transition zone in which warmer air mass is replaced by a colder one. This Buzzle post explains in detail about this weather phenomena and how does this mass form.
Winds are formed due to rotation of the Earth. Cold fronts being the front face of the air mass are dependent on the rotation of the Earth.
Air mass is a large structure of air which spans large distances. Front is a word used to describe the demarcation between air masses having different temperatures. These are of four types: stationery, occluded, cold, and warm front. In case of cold fronts, cold air moves towards warm air. In contrast, in case of warm fronts, warmer air moves towards the colder air masses. Cold front is a zone of transition. It progresses through the warmer air zones, thus changing their temperature.

Cold front has air masses in front and behind it. The one ahead of it is warmer, while the preceding one is colder and drier. They are known to move from north-west to south-east direction.

When the cold front moves through existing air masses, their temperature seems to decrease considerably. In the first two hours of the cold front passing, their existing temperature drops by more than 20ºC (68ºF).
Cold Front Symbol
Cold front symbol
The symbolic representation of this boundary consists of a straight line containing triangles placed uniformly over it. The triangles point towards the warmer air. They depict the direction in which the cool air is moving. The image given below shows the representation of a cold front.
How Does a Cold Front Form
Formation of cold front
The formation of cold front occurs when cold air lodges underneath the warm air mass. It develops between the low and high pressure zones. Since warm air has lower density, it is pushed upwards by the cold air. This transition witnesses changes (decrease) in the temperature of the warm air. This reduces the pressure of the cold front.
When the warm air is lifted, clouds form in the surrounding region. These clouds then condense and lead to precipitation or rain, which is usually brief but violent. However, note that enough moisture must be present for precipitation to occur. Thunderstorms or cyclones can occur too in addition to precipitation.
What Happens in a Cold Front
Simply put, the low temperature air moves through the warm temperature air. The features of a cold front are:
► Cold fronts replace air mass with a higher temperature.
► They have high density and move fast.
► They are steep in nature.
► The transition is followed by abrupt showers, which are for a short duration.
Weather Associated With Cold Front
The gliding of cooler mass over the warmer air often triggers bad weather conditions, which are characterized by cyclones, heavy rains, or thunderstorms. Though these are quite severe in nature, they seldom last long.

Cold air mass fronts, due to their high density, push the low density warm air mass in the upward direction. Warm air rises and starts getting cooler. As a result of which, clouds are formed and precipitation occurs. Hence, they are known to induce stormy weather.