How much one-time rainfall reaches is called rainstorm.

Rainstorm refers to the rainfall (100 ~ 200mm) whose 24-hour precipitation is greater than or equal to that stipulated by China's meteorological work.

Stable meridian type:

The first category is the stable meridional pattern. In this flow pattern, the westerly belt is dominated by meridional circulation, and the long-wave system moves slowly or stagnates. The subtropical high is also relatively stable, but it is located in the north. In this case, the mid-low latitude system can easily interact with each other. Stable meridional rainstorms are often the most serious, and some famous rainstorms in China's history have occurred under this circulation.

Stable band type:

The second category is the stable zonality type. At this time, zonal circulation prevails in the westerly belt of 35 ~ 55 N, with more short-wave trough activities, and the subtropical high is relatively stable, often zonal.

Reasons for the formation of extended data:

1, ITCZ (intertropical convergence zone) goes north.

2. A strong easterly jet formed between the offshore typhoon and the north subtropical high.

3. The combination of landing typhoon and mid-latitude westerly trough.

4. The upper trough overlaps with the easterly wave (or typhoon inverted trough).

5. The South Branch Trough interacts with the storm or typhoon in the Bay of Bengal in the South China Sea.

6. The southerly airflow in the northeast of the Bay of Bengal storm transported a lot of water vapor to the north.

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