How is the occlusion front formed?

When a warm air mass, a cooler air mass and a cooler air mass meet, they first form two fronts, and then one of them catches up with the other, that is, an occluded front is formed. It is common in our country that the front is blocked by mountains and the terrain is occluded; Or the cold front catches up with the warm front, or the two cold fronts meet head-on to form an occlusion. They force the warm air in front of the cold front to lift off the ground and trap it in the sky. We call the interface between the cold air mass behind the cold front and the cold air mass in front of the front as the occluded front. When the cold front catches up with the warm front, it forms the occluded front. It is difficult to determine the occluded front before the satellite cloud image appears. The occluded front is clearly shown on the satellite cloud image.

The meteorologists' theoretical research on fronts matured in the early 2th century. They believed that the fiercest weather in the atmosphere did not occur in cold and warm air masses, but at the junction of cold and warm air masses. Meteorologists define front as follows: cold and warm air masses meet in space, and the narrow transition zone between them with discontinuous meteorological elements is called front. The interface is called the front, and the intersection line between the front and the ground is called the front. In practical work, front and front are collectively referred to as front. The front is always inclined in space, and it is inclined to one side of the cold air mass. Warm air is above the front and cold air is below it. The length of the front line is several hundred to several Qian Qian meters, the horizontal width near the ground is about tens of kilometers, and it can reach more than 2 ~ 4 kilometers at high altitude, and the vertical thickness is several hundred meters to one or two kilometers.

there are three main conditions for the formation of occluded front: topographic occlusion formed by the front being blocked by mountains; Two cold fronts meet head-on; The cold front catches up with the warm front in temperate cyclone; In these cases, the warm air in front of the cold front is lifted off the ground and trapped in the sky. Therefore, the interface between the cold air mass behind the cold front and the cold air mass in front of the warm front is called the occluded front.

There are many ways to classify fronts, and the most commonly used ones are cold fronts, warm fronts, quasi-static winds and occluded winds.

occluded fronts can be divided into three types: warm occluded fronts, in which the cold air mass in front of the warm front is colder than that behind the cold front; The cold air mass behind the cold front is colder than that before the warm front. There is little difference in air mass properties before and after neutral occlusion front and occlusion wind.