Why is the cold front updraft stronger?

The cold front moves quickly and has a large slope, which is often called the second type cold front behind the 700hpa trough or near the high altitude trough line. The cold advection above this cold front is strong and the airflow sinks. Only the warm air near the ground front is lifted, but the front has a large slope and a strong airflow moves upward. The weather conditions in winter and summer are obviously different. In summer, the warm air mass is moist and unstable, and the strong cold advection on it becomes more unstable. Therefore, strong cumulonimbus clouds often form near the front line and are arranged near the front line like a cloud embankment. When the cold front comes, there will be thunderstorms and formation precipitation, but the rainfall area is only a few tens of kilometers. In winter, warm air before the front is located in front of the trough, and the airflow rises to form cirrus, cirrostratus, high-level clouds and nimbostratus. Near the ground front, there is a vast continuous precipitation area. After the precipitation stops, there is often a strong wind, also called a dry cold front.

Because the cold front moves fast and slowly, when the cold front moves slowly, the warm air will rise slowly and steadily, so it is easy to appear layered clouds and the rainfall is moderate. When the cold front moves fast, warm air will be lifted rapidly by cold air, which is easy to cause heavy cumulonimbus clouds, accompanied by lightning and heavy rain.