What does the map show?
The lightning map shows near real-time lightning observations in Norway, Sweden, Denmark and Finland. You can view lightning observations seconds after they are recorded and up to 24 hours back in time. The most recent lightning observations are animated and orange, older observations are shown on the map with two shades of purple (1-60 minutes) and two shades of gray (1-24 hours).
The map shows both lightning from cloud to cloud and from cloud to ground.
What is a lightning observation?
A lightning observation is a positioned discharge that is registered and calculated from two or more sensors.
How are observations measured?
The observations are measured with the help of a network of sensors. The sensors are basically a bearing antenna with a very accurate clock and a computer. A lightning discharge has a "signature" that allows the sensor's software to distinguish lightning discharges from all the other electrical noise in the world.
Time, direction and some other information about the lightning discharges are collected as a package of information which is sent to the Meteorological Institute's systems. Here, packets from all the sensors are sorted, and those that belong together from the same discharge, are then grouped together. The more sensordata, the more reliable is the calculated position for the lightning discharge.
The accuracy of the observations is around 200 metres.
The Meteorological Institute is responsible for the sensor network for lightning observations in Norway.