Lightning fast facts

    Why measure lightning

    Lightning is fascinating but dangerous. Humankind has wondered about it though history but now we can measure it to rein in its impacts. Lightning can kill and injure, damage infrastructure, delay recreation, and burn forests. With better understanding of lightning through precise detection, we can tell where, when, and how often it occurs, and take action based on this information.

    Types of lightning

    Billions of in-cloud and cloud-to-ground lightning events occur around the world every year. As the names suggest, in-cloud lightning are those events that occur entirely within a cloud, between multiple clouds, or between the cloud and the air. In-cloud lightning makes up the majority of lightning in thunderstorms. Cloud-to-ground lightning are the electrical discharges that connect from the cloud to the ground, or objects on the ground, like buildings, trees, and towers. Cloud-to-ground lightning is hazardous to life and property.

    Lightning detection

    It is now possible to use radio waves to detect every thunderstorm on earth, to locate nearly every cloud-to-ground flash, and detect many of the in-cloud lightning events that occur, without interruption. Some detection networks have been in continuous operation for over 30 years. It is important to measure how well this is done to make precise decisions on warnings, damages, and how often lightning occurs.

    What is a lightning network?

    Lightning detection networks are made up of a minimum of four lightning detection sensors that listen for the radio waves generated by lightning. These sensors are placed in specific locations to detect the most lightning with the highest accuracy. Lightning detection networks can cover a small region, like a portion of a state; an entire country; or even the whole planet. Lightning networks can use the time the radio wave reached the sensor, the direction the radio wave came from, or the time and direction to locate where lightning occurred.

    Network performance

    Since important decisions are made with lightning detection network data, how well they operate must be known. One basic way is the location accuracy, measured in meters. Also important is detection efficiency, the percentage of how much of the actual lightning is detected for a given area. Other critical measures are signal strength, polarity, and separating cloud-to-ground from in-cloud lightning.

    Global Lightning Density Map

    Global Lightning Density Map

    You can find out more about lightning around the globe by visiting the fascinating new global total lightning density map from Vaisala. Never before has it been possible to reliably compare lightning on a national basis everywhere.