NOTE:
No method of lightning warning completely eliminates the risks associated with lightning.
Lightning detectors give no warning until a detectable discharge has occurred. Atmospheric
electric field meters give warning prior to the first strike for storms developing overhead,
along with some indication of the end of a thunderstorm. However, there are occurrences of
cloud-to-ground lightning discharges striking the ground several miles from the electrified
cloud where the discharge originated [NOAA]. Electric field monitors may give no practical
warning in these instances because the electric field in the vicinity of the strike point may not
indicate hazardous levels until milliseconds before the strike. Consequently, while lightning
warning systems can greatly reduce the probability of death or injury from lightning
discharges, they cannot reduce this probability to zero.
7.3.1 All Clear
The All Clear state indicates all of the following:
l
The one- and ten-minute running averages of the electric field are both less than |±500
V/m|.
l
There have been no lightning strikes in the last 30 minutes.
l
If used, the SG000 shows no close (0 to 5 mi) or near (0 to 10 mi) strikes in the last 30
minutes.
At the All Clear state, RTMC display software shows No Lightning Strikes (SG000 option only) and
Low E_Field.
The blue light flashes on RA100 remote alarms.
7.3.2 Caution or Lightning Watch
The Caution or Lightning Watch state indicates any of the following:
l
The one-minute running average of the electric field is greater than |±1000 V/m|.
l
There are two or more lightning flashes within a 25-mile radius in a 5-minute period.
l
The SG000 shows distant (0 to 20 mi) strikes.
To return to a Caution state from an Alarm state, the following must occur:
l
The one- and ten-minute running averages of the electric field must both be less than
|±1000 V/m|.
l
The SG000 must show no close (0 to 5 mi) or near (0 to 10 mi) strikes in the last 30 minutes.
At the Caution state, display software shows E_FIELD CAUTION or LIGHTNING STRIKE CAUTION.
CS110 Electric Field Meter 17
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