Hold the shutter open for one or more hits of lightning. Close the shutter and advance film, repeat steps 1-5. An individual bolt can pack several hundred million volts at 10,000 amps, one trillion watts, briefly burning up more electrical power than is being used in the entire United States. To estimate how far away lightning is, count the seconds between seeing the flash and hearing the thunder. Each five seconds equals one mile.
Lightning can be erratic.
If you're closer to it than five miles, you can be struck. Take proper precautions when you photograph lightning. To photograph lightning during daylight is next to impossible. There's too much light to slow down the shutter speed enough to capture lightning even under the dark clouds of a heavy storm. Lightning takes its own picture when and where it wants, and no matter how fast your reflexes are, it's gone before the shutter opens.