If you see lightning, clear the field. If you hear thunder, clear the field. Play will be halted for a minimum of 30 minutes. If no lightning is spotted during the 30 minutes and/or no thunder is heard during the 30 minutes, play will resume. If lightning is seen and/or thunder is heard during the 30 minute period, the clock starts over. No play will resume until a minimum of 30 minutes passes with no thunder and/or no lightning.