Boltek Lightning/2000 - Manual (Page 221)

R E A L - T I M E L I G H T N I N G D E T E C T I O N
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Nearby Flashes
With the advent of version 4.6, we are for the first time able
to say with confidence that a particular lightning flash is
relatively nearby. This is a substantial advance over the
previous method that required the examination of groups of
flashes to come up with a range.
When a nearby flash is registered (as shown by the Nearby
Flashes counter), it is a sure sign that a storm is relatively
nearby (usually within 25 miles or 40 km). However, a nearby
flash gives no indication as to whether the storm is
approaching or receding.
With the release of version 5.4, we have added a refinement
of the nearby flash technique that allows far more nearby
flashes to be registered, with no false alarms. This new
technique however does not work with the LD-250, since it
depends on a special stroke type (called a Compact Intercloud
Discharge, or CID) that can only be discerned when using the
StormTracker hardware. The previously proven nearby flash
technique still works quite well with the LD-250 though.
Also in version 5.4, there is an option (in the Settings Dialog)
to require all nearby flashes (which consist of multiple
strokes) to contain CID strokes. This option produces good
results with storms that are fairly active; in particular it has
been observed to produce good results with strong to severe
storms in the United States. Storms that do not contain CID
strokes will fail to register any nearby flashes if this option is
enabled.