First you need to get acquainted with the concept of air mass.
|If the air over a territory with a diameter of 1600 km and more has about the same temperature and humidity, we call it an air mass.|
Tropical areas heat the air above them - warm air masses appear there, while the polar regions cool the air.
A front is the boundary between cold and warm air masses. If cold air moves forward, then the front is called cold, and if warm air moves forward, the front is warm. Why do we need to watch the fronts? They carry a change in the weather, clouds and precipitation are usually formed on the fronts.
It brings colder air and good visibility.
Now we should go into the concept of air stability.
|Stable air is the one that cools less than 1°C for every 100 meters of height. If air for every 100 meters cools more than 1°C, then the air is called unstable.|
So, if a cold front goes into stable air, then it usually carries thunderstorms and squalls. And if a cold front replaces unstable air, then layered clouds are usually formed, and then the sky becomes clear (this is why pilots prefer this front).
Usually the cold front passes in a few hours.
With a warm front, the sky is usually completely overcast – at a distance of more than 2,400 km. Warm fronts pass with rains, sometimes with thunderstorms.
Besides, warm fronts pass in a few days.