saw this approaching lightning storm and noticed that the lightning seemed to be occurring in multiple strikes. Every time it would strike, I would hit the shutter release, knowing that I would not get the first strike, but might capture a second or third. In 30 frames shot, I caught 10 with lightning strikes. This was just before sunset, but the clouds behind me were blocking out the setting sun. Just before the sun set, it dipped under the cloud layer for only a minute, lighting up the clouds on the right and creating the diffuse rainbow in the center of the image.