Abstract:

Microphysical structures and precipitation process of a stratiform cloud on May 1, 2009 in middle-east of China were analyzed by a one-dimensional stratiform cloud model. The results indicate that this precipitation process is caused by stratiform cloud, and the vertical structure of stratiform cloud is consistent with Koo Chen-Chao’s three-layer cloud conceptual model and “seeder-feeder” cloud mechanism. In the first layer (upper layer from 4.7 km to 7.0 km), there are ice crystal particles and snowflake, and the latter is formed in the way of sublimation and automatical conversion from ice crystal. In the second layer (middle layer from 2.6 km to 4.6 km), there are ice crystal particles,, snowflake, graupel, supercooled water droplets and rain droplets, and they are influenced significantly by the Bergeron process. In the third layer (lower layer from 1.3 km to 2.5 km), there are mainly cloud droplets, rain droplets, the melting snow droplets and graupel droplets from upper layers. The graupel droplets contribute greatly to the formation of rain droplets. When the cloud system develops maturely, there is a certain “seeder-feeder” relationship among the different layers. For example, the first layer supplies snow and ice crystal particles to the top of the second layer and the second layer sends graupel and snow particles to the top of the third layer.

Key words: Stratiform cloud, One-dimensional stratiform model, Three-layer cloud conceptual model, Microphysical mechanism