How lightning detection networks find a strike

01

How do lightning maps know where lightning struck?[1]

They use time-of-arrival triangulation. A lightning discharge emits a very low frequency radio pulse that travels thousands of kilometers at close to light speed. Ground stations timestamp the pulse with GPS-synchronized clocks, and the differences between those timestamps identify the strike location.

Because radio waves travel at roughly 300,000 km per second, a timing difference of one microsecond corresponds to about 300 meters of distance. Station clocks therefore need nanosecond-level synchronization, which GPS provides.

A minimum of three stations is needed for a two-dimensional fix, but real solutions typically use far more. Strikes shown on this site are commonly detected by 15 to 40 stations at once, and more contributing stations generally means a tighter position.

02

How accurate is lightning strike location?[1]

Community networks locate strikes to within a few kilometers on average. One published study of Blitzortung.org data found a mean error around 5.6 km. Commercial networks with denser station coverage achieve a few hundred meters. Accuracy depends heavily on how many stations detected the strike and their geometry around it.

Station geometry matters as much as station count. If every detecting station happens to sit on one side of a strike, the position is far less constrained than if they surround it. This is measured as the maximum circular gap: a gap above roughly 180 degrees means the strike fell outside the station ring, and the fix is weaker.

That location uncertainty is the dominant error in any thunder-timing calculation. At 343 m/s, an error of 5.6 km corresponds to about 16 seconds of arrival-time uncertainty, far larger than the fraction of a second gained by using a precise speed-of-sound formula. This site draws that uncertainty as a visible band around each wavefront rather than a single sharp ring.

03

Why is there a delay before strikes appear?

Strikes typically appear on a live map 3 to 8 seconds after they happen. The network needs to collect timestamps from multiple stations, transmit them to a central server, solve the triangulation and publish the result. That processing time is the delay you see.

This matters if you are using a map for safety. A strike shown as happening now actually struck several seconds ago, and a fast-moving storm covers real ground in that time. No live lightning map is truly instantaneous.

04

What do positive and negative strikes mean?

The polarity describes the charge transferred to the ground. About 90% of cloud-to-ground lightning is negative, carrying around 30,000 amperes. Positive strikes are rarer but far more powerful, reaching peak currents up to 400,000 amperes, and often strike well away from the storm core.

Positive strikes are the reason so-called bolts from the blue exist. They can originate from the upper anvil of a thunderstorm and hit ground more than 10 km from any rain, under apparently clear sky. They are disproportionately dangerous for exactly that reason.