Cold front cloud system of cold front

A cold front is a front formed by a cold air mass moving toward a warm air mass. Depending on how fast the cold air mass moves, cold fronts are divided into two categories: slow-moving cold fronts are called Type I cold fronts or slow-moving cold fronts, and fast-moving cold fronts are called Type II cold fronts or rapid-moving cold fronts.

The first type of cold front weather model

(1) The first type of cold front: This kind of front is located in front of the high-altitude trough line and is a multi-stable weather. This kind of front moves slowly and has a small front slope (about 1/100). The cold air behind the front forces the warm air to rise smoothly along the front. When the warm air is relatively stable and the water vapor is abundant, a range similar to that of the warm front will be formed. Extensive stratiform cloud system, but the cloud system appears behind the front, and the distribution order of the cloud system is opposite to that of the warm front cloud system. The precipitation properties are similar to those of the warm front. There are often stratocumulus clouds and broken rain in the precipitation area near the front. Cloud formation. The precipitation area appears behind the front and is mostly stable precipitation. If the warm air in front of the front is unstable, cumulonimbus clouds and thundershowers often appear near the ground front. Cold frontal weather that occurs in northwest my country, North China and other places in summer, as well as in southern my country in winter, mostly falls into this type.

Type 2 cold front weather pattern

(2) Type 2 cold front weather pattern: This is a cold front that moves fast and has a large slope (1/40-1/80) . The cold air behind the front moves much faster than the warm air mass. It impacts the warm air mass and forces a strong rise. At high levels, because the warm air mass moves faster than the cold air, the phenomenon of warm air sliding along the front occurs. Since this front is behind the high-altitude trough or near the trough line, the rising motion near the front and the subsidence on the high-altitude front area are strengthened. sports. In summer, near the ground front of this kind of cold front, strongly developing cumulonimbus clouds will generally appear, and convectively unstable weather such as thunderstorms, even hail, and squall lines will appear. On the upper level fronts, there are often no clouds forming. Therefore, the second type of cold frontal cloud system presents a narrow belt of cumulus clouds arranged along the front, like a cloud bank about ten kilometers wide and more than ten kilometers high. Altostratus clouds, altocumulus clouds, and cumulus clouds often appear in front of the ground front. When this kind of cold front passes through, there are often rolling dark clouds, strong winds, lightning and thunder, heavy rain, and drastic changes in meteorological elements. This kind of weather lasted only briefly. After the front passed, the sky suddenly became clear. In winter, due to the low humidity of the warm air mass, the temperature is unlikely to develop into strongly unstable weather. Cloud systems such as cirrus clouds, cirrostratus clouds, altostratus clouds, and nimbostratus clouds only appear in front of the front. When there is sufficient water vapor, there may be very thick and low clouds near the ground front, and continuous precipitation with a small width. After the surface front passes, the clouds quickly disappear, the wind speed increases, and strong winds often occur. In the dry season, the air humidity is low, the ground is dry and exposed, and there are also sandstorms. This kind of cold front weather often occurs in winter and spring in northern my country.

Cold fronts have a wide range of activities in our country, almost all over the country. Especially in the winter half of the year, they are more common in northern areas. They are one of the most important weather systems that affect the weather in our country. In winter, the air in mainland my country is dry, and cold fronts mostly enter the northwest region of my country from Siberia and Mongolia, and then move south. The cold air brought from Siberia meets the local warmer air, and precipitation rarely forms on the front. Therefore, cold waves and cold fronts pass through in winter. At that time, only strong winds and cooling weather were formed. In winter, there are many Type 2 cold fronts, which can affect as far as South China. However, after moving to the Yangtze River Basin and South China, they often transform into Type 1 cold fronts or quasi-stationary fronts. There are many types of cold fronts in summer, which have a small scope of influence, generally only reaching the Yellow River Basin. Summer thundershowers in northern my country are closely related to cold front activities.