When a lightning strike occurs a burst of energy is transmitted though the atmosphere much like a radio wave from a transmitter. Unlike a radio wave, however, lightning energy is not well ordered and spreads out across many different EM wavelengths.
Lightning detectors work much like a AM radio receiving signals from a tower. The detector contains special equipment that allows it to determine what direction, relative to the detector, the lightning strike occurred. The detector notes the polarity, amplitude, and exact time of the strike (determined by an extremely precise, GPS synchronized clock), then transmits that information back to a central hub. The detectors can detect strikes hundreds or even thousands of miles away. Inevitably a strike within the coverage area will be detected by multiple receivers, all of which transmit the strike data and time back to the hub.
Computers at the hub examine the incoming data and correlate strikes based on time and location. By using triangulation methods from the multiple detections, the hub can determine the precise location (down to 250 meters) where the strike occurred.
Data for all detected strikes are collected and transmitted from the lightning data collection hub to the weatherTAP Data Center. The weatherTAP Data Center continuously accumulates the data and renders a new lightning strike image every 10 minutes.
Standard lightning is displayed on the National Mosaic map. The National map allows you to view regional lightning in the US, Canada, and Mexico. Due to contractual terms, standard lightning can not be displayed in an area less than 5km x 5km and can only show 10 minutes or older strikes. RadarLab HD, also, has a default view of lightning in the standard display.
Real-time lightning data is available as an add-on option to our RadarLab HD product. This option allows the user to turn on a lightning layer with strikes portrayed as crosshair symbols, color-coded based on the age of the strike. The color codes and corresponding age ranges are user-adjustable. Unlike the standard lightning option, the real-time lightning symbols do not get larger with increased zoom levels. Regardless of the zoom area, the strike symbol stays the same size, resulting in a much more precise ground positioning. Users can also move the lightning coverage area around.
Real-time data is generally updated server-side, once-per-minute. Latency is generally on the order of a few seconds. Real-time data is provided for a fixed region, specified by the user when the option is enabled.
As part of the regular weatherTAP subscription, the lightning imagery is updated continuously, at 10-minute intervals. However, all strikes portrayed are a minimum of 12 minutes old at the time of posting. For real-time lightning data, available at an additional cost, please e-mail the webmaster at firstname.lastname@example.org or call 800-337-5263 from 7:00 am to 4:00 pm Central Time for details on pricing, coverage area, etc.
For the regular weatherTAP subscription, each strike is depicted by a solid, square symbol. The age of the strike is depicted by changing the color of the symbol. After 132 minutes, the strike is removed from the map.
The first image depicts the 12-minute age image available with the regular weatherTAP subscription. Each individual strike is represent by a block. The second image shows a sample of real-time lightning imagery, with a cross-hair symbol for each strike. This symbol does not get larger as the user zooms in. As mentioned above, real-time lightning is available at an additional cost to the regular subscription.