On Aug 15, 8:16 pm, "Danny Deger" wrote:
The engineer in me is dying to know how the sensors knows the difference
between cloud to ground and cloud to cloud. Anybody know.

Cloud to ground lightning creates a unique RF signature. By
recording these radio waves and by using time from GPS satellites to
corrdinate those receptions, then the NLDN could pinpoint those ground
strikes. When too many ground strikes occur, the network tends to
become overloaded; does not detect all strikes.

Then the NY Times made some inquires in response to a lightning
strike in the area of the former WTC that killed one person. Direct
lightning strikes known to have hit both the WTC and Empire State
Building (on average 25 and 40 times annually) were not detected;
apparently did not create that RF signature. No followup information
is available as best I can tell.