Lightning

  • Image, Lightning.

    Lightning is the discharge of electricity from thunderstorms and can occur within a cloud, between clouds, or between a cloud and the ground. By international standards, lightning does not occur frequently around New Zealand. However, lightning strikes can injure or kill people and livestock, damage property and infrastructure, and, although rarely in New Zealand, spark forest fires. Localised severe weather events such as strong wind gusts, heavy downpours, strong downdraughts (a danger to aviation), and hail, are often caused by thunderstorms. In New Zealand, thunderstorms are the source of most tornadoes. Thunderstorms may increase in frequency and intensity with climate change.

    We classified Lightning as a national indicator.

    Key findings

     Image, Indeterminate trend.  Indeterminate trend

     

    From 2001 to 2016, the New Zealand region (land and approximately 500 kilometres out to sea) received about 187,000 ground and sea strikes a year.

    • From 2001 to 2016:
      • parts of the West Coast in the South Island had the highest annual average density of ground strikes, up to 40 per 25 km2 a year.
      • parts of the Taranaki, Waikato, and Bay of Plenty regions were prone to lightning, with an annual average of up to 16 ground strikes per 25 km2 a year in some areas.

    • From 2001 to 2016, no trend could be determined at the 95 percent confidence level in the national annual number of lightning strikes.

    Figure 1

    Note: Only data for full years is displayed although data are available from September 2000.

    Figure 2

    Average annual lightning ground and sea strikes, 2001–16 – interactive map

    Map, Average annual lightning ground and sea strikes, 2001–2016.

                                                                                                           Source: MetService courtesy of Transpower New Zealand Limited

    Definition and methodology

    Thunderstorms form as a result of moist air rising rapidly through a considerable depth of the atmosphere – in New Zealand, typically to about 30,000 feet. Deep clouds that have formed by the rapid ascent of air may become electrified.

    Lightning is the discharge of electricity from thunderstorms. It equalises areas of positive and negative charge, for example, between a storm cloud and the ground.

    The New Zealand Lightning Detection Network (NZLDN) owned by Transpower and operated by MetService records cloud-to-cloud and cloud-to-ground lightning strikes. A network of 10 sensors around the country detects lightning over the New Zealand land mass and a short distance out to sea (approximately 500km). These sensors detect the polarity of the electrical discharge, time, and current strength. Lightning strike location is determined by triangulating the data from two or more lightning sensors; in general, location accuracy is approximately 1km.

    Thunderstorms are projected to become more frequent and intense with climate change (Mullan et al, 2011).

    Data quality

    We classified Lightning as a national indicator.

    Relevance

       This national indicator is a direct measure of ‘Climate' topic.

    Accuracy

       The accuracy of the data source is of high quality. 

    See Data quality information for more detail.

    References

    Mullan, B, Carey-Smith, T, Griffiths, G, & Sood, A (2011). Scenarios of storminess and regional wind extremes under climate change (PDF 8MB). Retrieved from www.niwa.co.nz.

    Archived pages

    See Lightning (archived October 2017).

     

    Updated 19 October 2017

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