气流辐合

沙尘天气发生必须具备三个条件：沙源、大风、气流辐合（垂直对流）。

The three reasons or conditions are respectively sand source , strong wind and violent vertical air current in the different periods of seasons in a year .

对流层臭氧浓度的分布与气流的辐合辐散存在较好的对应关系，辐合区臭氧浓度较高，辐散区臭氧浓度较低。

In addition , higher ozone concentrations are coincided with the air convergence , and the lower are related to the air divergence .

地形切变线一般在30°-210°出现，随着强对流天气的发展，零速度线位置、形状、两侧气流的辐合、辐散均发展变化。

Topography shear line appears along the direction line of 30-120 ° . With development of convection weather , zero velocity line has a change in position , shape , convergence or divergence of the airflow in two sides .

在所有的观测结果中，迎风坡坡度为15°的沙丘具有最大的沙粒起动风速和最远的气流重新辐合距离，其原因尚需进一步研究。

According to these results , the flow reattachment distance in the lee side of transverse dunes can be determined . Finally , we think that there is a further research need on the 15 ° stoss slop because it had the maximum threshold wind velocity and re-attachment distance .

低空偏南气流的风速辐合场，在925hPa层上最明显。

The wind speed convergence of south-west wind at low level was the most obvious at 925 hPa .

降水、下沉气流、气流辐合区、冷锋锋面会导致草地螟集中降落。

Precipitation , atmospheric subsidence , air convergence , and cold front will lead convergent landing of meadow moth .

尾部的向前移动方式是传播性的，且与近地层气流的辐散辐合紧密联系。

The forward movement of the tail is in a way of propagation and closely linked with divergence and convergence of near surface flow .