## 3 Results
### Event 1 on 17 April 2023 at 04:13 UTC
Discharges with higher group energy occurred between 04:13:04.000 UTC and 04:13:04.500 UTC, as indicated by the presence of orange and yellow dots in the GLM plot in Figure 4. The group energy higher than \(1.00\times 10^{-13}\) J was detected as \(1.22\times 10^{-13}\) J, \(1.65\times 10^{-13}\) J, and \(1.60\times 10^{-13}\) J at 4.035 s, 4.037 s, and 4.043 s, respectively, corresponding to the time window of the orange dots. Additionally, a group energy of \(1.23\times 10^{-13}\) J is detected at 4.271 s, with the highest group energy in the timeframe detected as \(2.25\times 10^{-13}\) J at 4.436 s, corresponding to the yellow dots. The time of the high group energy of \(1.23\times 10^{-13}\) J corresponds to the time between the frames of 4.256 s and 4.296 s shown in Figure 2, occurring immediately after the visible discharge and the brighter luminosity in the frames. Figure 6 represents weather maps, which is reported by weather.us [47], corresponding to the area and timeframe of the GLM map shown in Figure 4. The selected times for the weather maps are the closest to and immediately following the timeframe of the GLM map. Figure 6a-c display a storm map at 04:13:48 UTC, which updates every 5 min, a precipitation map at 05:00 UTC, which updates hourly, and a cloud-top map at 04:15 UTC, which updates approximately every 5 min, respectively. The white circle in Figure 6a-c indicates the area of the cluster of red, orange, and yellow dots during the timeframe from 04:13:03.5 UTC to 04:13:04.5 UTC. By comparing the timeframe and area where the red, orange, and yellow dots occurred in Figure 4 to the area marked with the white circle in Figure 6a-c, it is evident that the intense storm was passing through the area when the dots occurred. During this period, there was an observed increase in precipitation, while the cloud-top height decreased immediately after the occurrence of those dots. Figure 3: A recorded horizontal discharge at 04:13:04.215 UTC. Figure 2: Video-recorded images from 04:13:04.135 UTC to 04:13:04.899 UTC on 17 April. The images are captured by the camera, iPhone 13 ProMax, operated at a frame rate of 24.88 fps, resulting in a frame-to-frame interval of 40.19 ms. The camera’s location is the coordinates of 26.3468\({}^{\circ}\) N and 81.7996\({}^{\circ}\) W.  
Figure 4: Lightning locations reported by the GLM data on 17 April from 04:13:03.500 UTC to 04:13:05.500 UTC. The map displays a view of the coordinates of 25.95\({}^{\circ}\) N–26.35\({}^{\circ}\) N and 81.5\({}^{\circ}\) W–82.0\({}^{\circ}\) W. The colored dots represent the lightning flash locations, with a color dot scale ranging from red to violet within a 0.25 s time window. The total number of lightning detections in each range window is displayed in the box at the upper right corner of the figure. Yellow and blue lines represent transmission lines and river/canal lines, respectively. Clean-IR brightness temperature with longwave 10.3 μm, with units of Kelvin as in absolute temperature. Figure 5: Group energy of lightning discharges reported by GLM from 04:13:03.750 UTC to 04:13:05.500 UTC. The time shown along the horizontal axis indicates the seconds within 04:13 UTC. Given the absence of any detected event from 3.50 s to 3.75 s, the initial time of this plot is set to 3.75 s. Discharges with higher group energy occurred between 04:13:04.0 UTC and 04:13:04.5 UTC, as indicated by the presence of orange and yellow dots in the GLM plot in Figure 4. The highest energy was detected at 04:13:04.4366 s.