Hot lightning

Key findings of the study-

• The the study titled, ‘Variation of lightning-ignited wildfire patterns under climate change’, has been done by researchers from Spain and Germany.
• According to the researchers, lightning is a major cause of triggering wildfires and is responsible for producing the largest wildfires in some regions, including the Western United States. 
• Lightning-caused wildfires are dangerous as they spread rapidly before a strong response can be implemented and release substantial amounts of carbon, nitrogen oxides and other trace gases into the atmosphere.
• Although previous studies have demonstrated that climate change might lead to an increase in lightning strike incidents, the latest research is the first time that scientists have focused on the relationship between “hot lightning” strikes and rising global temperatures. 
• Moreover, they have also examined how this form of lightning might affect the incidents of wildfires across the world.
• The researchers analysed 5,858 selected lightning-ignited fires based on satellite images of US wildfires between 1992 and 2018 and found that approximately 90 per cent of them might have started by “hot lightning” strikes. 
• Also known as long continuing current (LCC), this type of lightning strike can last from around 40 milliseconds to nearly a third of a second.
• Explaining why “hot lighting” has more potential of triggering a wildfire than typical lightning, the new study, told that lightning with continuing currents can transport more energy from cloud to ground than typical lightning. 
• When lightning with continuing currents attach to ground or vegetation, they produce more Joule heating and higher temperature than typical lightning, increasing the probability of ignition.
• With the help of computer simulations, the researchers also looked at the frequency of “hot lightning” strikes and observed that as the atmosphere warms, there might be an increase of 41 per cent in the incidents of LCC strikes by 2090. This means that the rate of such lightning flashes could jump from three strikes per second globally to four strikes per second. 
• Meanwhile, the frequency of all cloud-to-ground strikes might increase to nearly eight flashes per second, a 28 per cent jump.
• According to the study, the areas that might witness a significant increase in wildfires triggered by the LCC strikes are Southeast Asia, South America, Africa, Australia, North America and Europe. 
• The researchers predicted this after accounting for changes in precipitation, humidity and temperature. 
• However, many northern polar regions might see a decrease in wildfires as rainfall is projected to increase while “hot lighting” rates remain constant.