DMI's network of lightning sensor registers lightning activity over Denmark and the surrounding area. The lightning sensors are located in Sindal, Bovbjerg, Rømø, Hellebæk, Gedser and Rønne. The network of sensors detect lightning between cloud and ground as well as lightning from cloud to cloud. The lightning sensor network detects about 90% of the lightning, which strikes the ground.

When lightning strikes, a strong electromagnetic wave is generated, which spreads in all directions from the trigger point. The individual sensors register the time, the amperage and the direction to the lightning stroke in relation to geographical north. The information is then sent to the DMI in Copenhagen, where the point of impact can be localized by triangulating the data from two or more sensors, which have registered the lightning at the same time.

Lightning strokes are registered with an accuracy of 500-2000 meters.

In order to do as precise a triangulation as possible, DMI includes data from 3rd party lightningsensors in the calculation of the point of impact. Data from these 3rd party sensors are used for calculation purposes only and is not available through the lightning service. 

The lightning data service offers triangulated lightning data (observation) as well as the data each of DMI's lightning sensor has detected (sensordata).