Streamer discharge theory does not consider the influence of airflow on discharge. However, it is found experimentally that the airflow causes a great change in the breakdown process, especially in a nonuniform field. In this paper, a physical model of spark discharge in airflow is established considering the combined effect of the decrease in airflow density and the blowing away of positive ions and electrons on the breakdown process. Furthermore, the classic streamer breakdown criteria both in uniform field and nonuniform field are modified. This model extends the classic streamer breakdown criterion for static gases to the airflow environment.
