An Investigation on Spatiotemporal Sizes of Specific Types of Lightning Flashes

Abstract

AbstractThe duration and horizontal extension distance (HED) of intracloud (IC), negative cloud‐to‐ground (NCG), positive cloud‐to‐ground (PCG), and bipolar cloud‐to‐ground (BCG) lightning are analyzed using data from the Oklahoma Lightning Mapping Array and the National Lightning Detection Network. All of these conform to lognormal distributions. BCG lightning has the greatest average spatiotemporal size, owing to its longest‐duration and largest‐spatial‐extension discharge process after the first return stroke (RS). Compared with NCG lightning, PCG lightning tends to include longer‐duration and greater‐spatial‐extension discharge processes before the first RS, making the latter have a larger average spatiotemporal size. IC lightning exhibits the smallest average spatiotemporal size, with a higher concentration of samples in smaller size intervals. Overall, as lightning initiation heights increase, IC and NCG lightning duration tends to increase, while NCG lightning variation is mainly due to discharge processes before the first RS. HED of both types initially increases and then decreases, peaking at ∼7 km. The horizontal extension speed (HES) of IC lightning tends to decrease with increasing initiation height, while for NCG lightning, the HES associated with discharge processes before the first RS shows a clearer decreasing trend at higher levels. The NCG lightning initiated below ∼6 km tends to exhibit similar HED before the first RS and increased HED after the first RS. However, for NCG lightning initiated above ∼6 km, the HED before the first RS is notably greater than the increased HED after the first RS.