Recent mention of thunderstorms reminded me of the 30/30 rule. This is designed to reduce the risk of being struck - a very real risk for hilltop radio operators. The rule is this:
If the time between the lightning flash and the arrival of the thunder is less than 30 seconds, you should get into a safe location. You should then remain there for 30 minutes after the last thunder is heard (or flash is seen).
- UK only.