The calculation was run on a 350 km 110 km grid with 1 km 1 km resolution. The region below 50 km was assumed to be free space. The color scale indicates magnitude of the electric field, while red contours show intensity of optical emissions. The contour values are at photons cm s .
Time is measured from the onset of the return stroke current.
The inset box shows the injected model lightning current and its integral over time. The format is similar to Figure 2.5 but the input current is much slower. Figure 2.5 shows snapshots at various times over the course of 1 ms following the onset of a short-duration vertical lightning return stroke current flowing between 10 km altitude and the ground. The color scale shows only the magnitude of the vector electric field, while the red contour lines indicate the intensity of optical emissions in the band. There are two regions of strong electric field evident in the simulation results.