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Lightning is one of the most common atmospheric hazards, and is one of the top three causes of storm-related fatalities (Jensenius Jr., 2014a). It is also a poorly understood hazard by the public with a greater percentage of outdoor fatalities in the 1990s compared to the 1890s (Holle et al. 2005). Lightning occurs in multiple forms, ranges of intensity and polarity, and can occur in all convective storm types throughout the year. Despite the danger to life and property, lightning remains an often-ignored severe weather hazard.
There are two main types of lightning, intra-cloud lightning (IC) and cloud-to-ground lightning (CG) (Jensenius Jr., 2014b). CG lightning is more familiar yet less common, comprising only about 25% of lightning strikes (NASA Science, 2001). CG lightning can be either positively or negatively charged with negatively charged CG lightning most common. Although most lightning occurs during the summer, thunderstorms which produce CG lightning can occur any time of the year in the United States (NOAA, 2015). Lightning is most likely to occur in locations with warm, moist lower atmospheric conditions and higher surface temperatures resulting in higher frequencies during the summer months (NSSL, 2014). The increase in lightning activity during the summer months (Curran et al. 2000) also coincides with an increase in outdoor and recreational activity, leading to an increased threat. From 2006 to 2013, almost two thirds of the deaths in the United States attributed to lightning occurred due to these summertime activities (Jensenius, 2014a). Lightning can also cause damage to structures, outdoor industrial and electrical equipment, livestock and outdoor animals, and can cause fires (Curran et al., 2000; Stocks et al., 2002; Krausmann et al., 2011; Gomes, 2012).
Despite the danger to life and property, lightning-related casualties and economic damages continue to occur every year. It is believed that this is due in part to the common yet temporally dispersed nature of lightning strikes (Ashley and Gilson, 2009). Lightning-related casualties and damages are underreported and receive less attention than other severe weather hazards (Curran et al., 2000). Curran et al. (2000) also note that there may be unquantified losses as a result of underreporting, which may mask the true reality of lightning-related hazards. Research which assesses lightning casualty and damage reports often utilizes only one source, such as the National Climate Data Center’s (NCDC’s) Storm Data. Storm Data reports a monthly list of damaging or notable weather phenomena but often includes missing data elements due to its reliance on newspaper clippings (Curran et al., 2000; Ashley and Gilson, 2009).