De legenda staat onder het 'i' tje in de linker bovenhoek.
En de bewegende cirkels is het geluid.
Citaat:
Strokes of the last 60 minutes are shown. The real-time data comes directly from the computing servers of Blitzortung.org, which are fed by hundreds of stations on several continents. The delay is calculated from the time stamps of each strokes compared to the current time.
Legend:
New lightning strikes have a red circle which gets smaller and disappears when it gets older than 30 seconds.
The color of filled circles represent the age of strikes up to 60 minutes. New strikes are yellow. The older they get, the darker the color. Dark brown is equal to almost 60 minutes. Those strikes will vanish soon.
On higher zoom levels the thunder front of current strikes is shown as white transparent growing circle (speed of sound). It gets more transparent while travelling and disappears after a while.