What is warm front weather?

The gradient of warm front is very small, about1150. Because warm air generally contains a lot of water vapor and plays a leading role, it can reach a very high height by actively rising forward and slowly sliding upward on the cold air mass. Warm air is adiabatically cooled in the rising process, and after reaching the condensation height, a cloud system is formed on the front. If the warm air slides high enough and the water vapor is sufficient, a broad and systematic layered cloud system will often appear on the warm front. The order of cloud system is cirrus, cirrostratus, stratus and nimbostratus. The thickness of the cloud varies according to the rising height of warm air, which can generally reach several kilometers, and the thick cloud can reach the tropopause. The closer it is to the ground, the thicker the frontal cloud is. Warm front precipitation mainly occurs in nimbostratus, which is continuous precipitation. The width of precipitation varies with the slope of the front, generally around 300~400 kilometers. Because of the uneven distribution of air humidity and vertical velocity, the warm front cloud system is sometimes discontinuous, and there may be dozens or even hundreds of kilometers of cloudless gaps.

In the cold air mass under the warm front, stratocumulus and cumulus are often produced under the action of airflow convergence and turbulence because of the humidity of the air. If the raindrops falling from the front warm air evaporate in the cold air mass, the water vapor content in the cold air mass will increase, and when it reaches saturation, cumulus clouds and stratocumulus clouds will be produced. If this saturated condensation occurs in the ground layer near the front line, frontal fog will be formed. The above is the general situation of warm front weather, but when the warm air is unstable in summer, there may be showers such as cumulonimbus clouds and thunderstorms. When the water vapor content in the warm air mass is very low in spring, only some high clouds appear and there is little precipitation.

There are few obvious warm fronts in China, and most of them are accompanied by cyclones. In spring and autumn, it generally appears in the Jianghuai Basin and Northeast China, and it mostly appears in the Yellow River Basin in summer.