The voltage must build up sufficiently to overcome the air's resistance, an electrical breakdown voltage.

电压必须足够高以克服空气的阻力，即电击穿电压。

Chapter 4: The Climactic Discharge Once the electrical tension surpasses the air's breakdown voltage, a path of ionized air, called a " step leader, " descends from the cloud.

第四章：高潮放电 一旦电压超过空气的击穿电压，一条被称为“先导”的电离空气路径就会从云中下降。