. Process of formation of the fronts is known as frontogenesis. There are four types of fronts:
When the cold air moves towards the warm air mass, its contact zone is called the cold front. As the cold front nears your region, the barometer falls. The cold air behind the front wedges under the warm air and lifts it sharply off the ground. Large cumulonimbus clouds appear. These clouds often bring thunderstorms and rain showers. As the cold front passes, the wind changes direction. The weather becomes clear and colder and the barometer rises again.
Whereas if the warm air mass moves towards the cold air mass, the contact zone is a warm front. The warm air behind the front glides up and over the cold air. The barometer falls and a long, steady rain begins. Gradually, the front passes and the sky clears.
When an air mass is fully lifted above the land surface, it is called the occluded front. it results when a cold air front overtakes a warm front and lifts the warm air mass completely off the ground. An occluded front forms when a cold front overtakes a slower-moving warm front. The occluded front is more complicated than the others because two fronts interact. In the left diagram of the occluded front, colder air wedges under warm air at the cold front. Warm air is glides up and over another cold air mass at the warm front. As shown in the right diagram of Occluded front, the warm air is squeezed out and lifted above the ground. Steady rains falls at an occluded front.