Answer:
This occurs due to the convergence of different air masses with different temperatures, density, and humidity. The turbulent conditions are produced, and cyclonic rain occurs along the fronts of the cyclone. The layer separating them is known as a front. The front has two parts – the warm front and the cold front.
At the warm front, the lighter warm air that is less dense usually forced to rise over denser cold air and thereby leading to cyclonic rain. A variety of clouds get formed, and they generally lead to moderate to heavy rainfall.
Causes for Occurrence of Frontal Rainfall
A tropical warm air mass comes in contact with a cold air mass of polar region. The less-dense, lighter warm air is then forced to rise over the denser, cold air.
It causes warm air to become cold. As the warm air is forced to rise further, it condenses to form the stratus cloud.
After becoming saturated, the stratus cloud begins to precipitate.
Frontal or cyclonic rain falls gradually for a few hours which can also extend up to a few days.
It is prevalent in Britain and Ireland, which is associated with the movement of depressions over the country. In north-west Europe, warm oceanic air and cold continental air converge to produce heavy rainfall in adjacent areas.
