Weather conditions of cold air transit

When the cold front crosses the border, it will be accompanied by the increase of northerly wind, the increase of air pressure and the decrease of temperature, sometimes causing rain and snow, and even causing heavy rain in summer.

Cold front is the most common front in China, which can be moved to all parts of the country. Because of the different configurations and moving speeds of the cold front and the upper trough, the distribution of clouds and precipitation near the cold front is obviously different, and some of them mainly appear behind the front; Others mainly appear in the front.

During the front movement, the cold air mass plays a leading role, pushing the front to move to one side of the warm air mass. This front is called a cold front. After the cold front crossed the border, the cold air mass occupied the original position of the warm air mass. Because cold air is heavy and warm air is light, when the cold air mass moves, it will form a cold air mass that actively wedges under the warm air mass, forming a front at the junction of cold and warm air.

When a cold front crosses the border, cumulonimbus clouds, thunderstorms and heavy precipitation often occur. If the cold front moves fast, cumulonimbus clouds are distributed in the narrow area in front of the front, and then it will turn from local cloudy to sunny quickly after the front; If the cold front moves slowly, it will form a large range of high-level clouds and nimbostratus.

Time and place of appearance

Strong in winter and weak in summer, with similar frequency. Its shape and moving speed are greatly influenced by the terrain. The general characteristics of cold front activity: there is cold front activity in East Asia. The frequency of cold front is more in the north than in the south, and the frequency of cold front in the southwest is the smallest. Half a year in winter is more than half a year in summer, with the most in spring and the least in autumn.

The cold front is the strongest in winter, which can often directly drive South China and South China Sea, resulting in cold wave weather. The cold front in summer is weak, mainly in the north, and it often brings thunderstorms.

North China is the only place for cold front activities in China. In Northeast China, there are cold fronts all year round, especially in spring and autumn. There are three sources of cold front in these two areas: West Road, Northwest Road and Beibei East Road.

The cold front in winter mainly causes cooling and strong winds, and thunderstorms can occur in summer. In spring, cold fronts often cause strong winds and precipitation in Northeast China, but only sandstorms in North China.