Traditional Culture Encyclopedia - Weather forecast - What is the difference between cold front rain and warm front rain except that it rains in different areas?

What is the difference between cold front rain and warm front rain except that it rains in different areas?

The first cold front weather model

(1)I-type cold front: This front is in front of the upper trough line, and the weather is more stable. This front moves slowly, and its slope is not big (about1100). The cold air behind the front forces the warm air to rise steadily along the front. When the warm air is relatively stable and the water vapor is abundant, it will form a wider layered cloud system similar to the warm front, but the cloud system appears behind the front, the distribution order of the cloud system is opposite to that of the warm front, and the precipitation property is similar to that of the warm front. The precipitation area appears behind the front, mostly stable precipitation. If the warm air in front of the front is unstable, cumulonimbus clouds and thunderstorms often appear near the ground front. Most of the cold front weather in northwest and north China in summer and in south China in winter belong to this type.

The second kind of cold front weather model

(2) The second cold front weather model: this is a cold front with fast moving speed and large slope (1/40- 1/80). The cold air behind the front moves much faster than the warm air mass, affecting the warm air mass and forcing it to rise strongly. On the other hand, at the top floor, because the warm air mass moves faster than the cold air, the warm air slides down the front. Because this front is located behind the trough or near the trough line, the rising motion near the front and the sinking motion in the upper front area are further strengthened. In summer, strong cumulonimbus clouds usually appear near the ground front of this cold front, and convective unstable weather such as thunderstorm, hail and squall line appears. At the top, there are often no clouds. Therefore, the second kind of cold front cloud system presents a long and narrow accumulation cloud belt arranged along the front line, like a cloud dike with a width of about 10 km and a height of 10 km. Stratospheric clouds, cumulus clouds and cumulus clouds often appear in front of the ground front. When this cold front crosses the border, dark clouds often roll, strong winds blow, lightning flashes and thunder rumbles, heavy rains pour down, and meteorological elements change dramatically. This kind of weather lasted for a short time. After crossing the front line, the sky suddenly cleared up. In winter, due to the low humidity of the warm air mass, it is impossible for the temperature to develop into strong unstable weather. Only cirrus, cirrostratus, stratus, nimbostratus and other cloud systems appear in front of the front line. When the water vapor is sufficient, there may be thick and low clouds and small continuous precipitation near the ground front. After the ground front crosses the border, the clouds quickly disappear, the wind speed increases, and strong winds often appear. In dry season, the air humidity is low, the ground is dry and bare, and there will be sandstorm weather. This cold front weather mostly occurs in winter and spring in northern China.

The cold front has a wide range of activities in China, almost all over the country, especially in the winter half year, and it is more common in the northern region. It is one of the most important weather systems that affect the weather in China. In winter, the air in Chinese mainland is dry, and the cold front mostly enters the northwest of China from the Soviet Union and Mongolia, and then goes south. The cold air brought from Siberia meets the local warmer air, and there is almost no precipitation on the front. Therefore, when the cold front crosses the border in winter, only strong winds are formed to cool down. There are more than two types of cold fronts in winter, which can reach South China, but after moving to the Yangtze River basin and South China, they often turn into one type of cold front or quasi-static front. There is more than one cold front in summer, which has a small influence range and generally only reaches the Yellow River Basin. Thunderstorm weather in summer in northern China is closely related to cold front activity.

Warm front and warm front cloud system

When the warm air mass moves forward and the cold air mass retreats, the front formed at this time is the "warm front". 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 systems is Cirrus (Ci), cirrostratus (Cs), Stratosphere (As) and nimbostratus (Ns). The thickness of clouds varies with the rising height of warm air. Generally, it can reach several kilometers, and the thick one can reach the tropopause. The closer to the ground front, the thicker the clouds are. 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 km. The warm front cloud system is sometimes discontinuous because of the uneven distribution of air humidity and vertical velocity, and there may be dozens or even hundreds of kilometers of cloudless gaps.

Warm front weather patterns

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.

Quasi-static front and continuous rain

A front that rarely moves or moves slowly is called a quasi-static front. The cold and warm air masses on both sides of it often form a "confrontation" state. The warm air mass was blocked by the cold air mass and forced to slide along the front. The situation is similar to the warm front, and the cloud system looks roughly the same as the warm front. Because the slope of the quasi-stationary front is smaller than that of the warm front, the warm air sliding along the front can extend away from the front, so the cloud area and precipitation area are wider than that of the warm front. However, the intensity of precipitation is small and the duration is long, which may cause continuous rainy weather.

Quasi-static frontal cloud system

Quasi-static frontal weather is generally divided into two types: one is the development of cloud system on the front with obvious precipitation. For example, the quasi-static front in South China is mostly formed by the weakening of the cold front. The weather is similar to the first kind of cold front, but the front slope is smaller and the cloud area and precipitation area are wider. The precipitation area is not limited to Feng Yu area, but can extend to a large area behind the front, and the precipitation intensity is relatively small, which is continuous precipitation. Because the quasi-static front moves slowly and often swings back and forth, the rainy weather lasts for 10 days to half a month, or even more than a month. "It rains in succession during the Qingming Festival" is a portrayal of this kind of weather in the south of the Yangtze River. This rainy weather will not clear up until the quasi-stationary front becomes a cold front or the warm front moves out of the area or the front disappears. In early summer, if the humidity of the warm air mass increases and the lower layer heats up, the gas layer may be unstable, and cumulonimbus clouds and thunderstorms may also form on the front; The other is the quasi-static front where the main cloud system develops under the front, and there is no obvious precipitation, such as the quasi-static front in Kunming. Because the cold air in the south is blocked by mountains, it is in a static state, and the warm air on the front is dry and slowly rising, which cannot produce a large range of cloud systems and precipitation. However, the cold air under the front slides upward along the hillside and is mixed with turbulence, which can form a less thick nimbostratus under the front, often accompanied by continuous precipitation.

The quasi-static fronts in China mainly appear in South China, Southwest China and the north side of Tianshan Mountain, mostly in winter, lasting for half a year, which has a great influence on the weather in these areas and their vicinity.

Blocking front and weather

Blocking front is a new front formed by cold front catching up with warm front or two cold fronts meeting, lifting warm air to high altitude and merging the original front. Its weather retains the characteristics of the original frontal weather. For example, the blocking front is formed by cold and warm fronts combined with layered cloud system, and the cloud system of the blocking front is also layered cloud, which is distributed on both sides of the blocking point. If the original cold front is cumulus, then the cumulus is connected with the stratiform cloud of the warm front after shielding. The blocking frontal precipitation not only retains the characteristics of the original frontal precipitation, but also develops further because of blocking. Warm air rises above the blocking point, which makes the cloud body thicker, the precipitation increases and the precipitation area expands. According to the cold and warm of the front, the corresponding cloud system appears on the front below the occlusion point. When the blocked front crosses the boundary, there is more complicated weather associated with the original front.

The blocking fronts in China mainly appear in Northeast China and North China, where frontal activities are frequent, most in spring. The blocking fronts in Northeast China are mostly from Mongolia and the Soviet Union, and they are mostly cold blocking fronts. The blocking front in North China mostly occurs locally and belongs to warm blocking front.