Lightning is one of the most spectacular natural phenomena, having captivated humans for centuries, sparking both awe and fear. It has inspired myths and legends in the past and is even credited with providing some of the energy for the creation of life itself. Today, scientists know exactly why lightning strikes, but predicting where it will strike is much more difficult due to all the factors at play. In fact, the word has become synonymous with unpredictability. But scientists all over the world are trying to uncover these mysteries.
In a new study, researchers from the Indian Institute of Tropical Meteorology (IITM), Ministry of Earth Sciences, Hemvati Nandan Bahuguna Garhwal University, and Banaras Hindu University (BHU) have studied how the landscape affects lightning strikes. They have delved into understanding the frequency of lightning in North India (NI) and North-East India (NEI), discovering how land use and topography might predict when and where these electrical bursts will occur.
For their study, the researchers poured thorough data from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite, recording the location and frequency of lightning strikes between 2001 and 2014. They then combined this lightning data with information about the different types of land in the area - forests, farms, cities, and so on - obtained from another satellite, Moderate Resolution Imaging Spectroradiometer (MODIS). For topographical details, they consulted the Shuttle Radar Topography Mission or SRTM—a source of detailed 3D maps of Earth's surface.
They also looked at weather-related factors like temperature, humidity, and something called Convective Available Potential Energy (CAPE). CAPE measures how unstable the atmosphere is and how likely it is to produce thunderstorms. They also analysed total cloud cover liquid water (TCCLW) and total cloud cover ice water (TCCIW) along with lightning flash rate density (LFRD) to determine the local temperatures and amount of moisture in the air. They then used computer programs to classify each strike, overlaying their locations on MODIS images to see which land types were struck by lightning. By examining topographical elevations, they categorised these lightning locations by height, revealing patterns at different altitudes.
The study found that the type of land plays a significant role in the density of lightning strikes. Firstly, North India (NI) generally experienced more lightning than Northeast India (NEI). However, the timing differs: NI sees a peak in lightning during the monsoon season (June to September), while NEI is more prone to lightning strikes during the pre-monsoon months (March to May).
Areas with lots of human activity, like farmland and cities, were also shown to have more lightning strikes. Without vegetation covering it around the year, the ground over farmlands heats up quickly, creating the perfect conditions for thunderstorms. Natural landscapes, like forests and grasslands, were shown to have moderate lightning activity, showing us that vegetation, which helps maintain high soil moisture, plays a role in lightning occurrences. Some natural areas, like savannas (grasslands with scattered trees) and wetlands, can also be lightning hotspots.
The mountains also matter. The research revealed that lightning is more common in the foothills of the Himalayas. It is likely caused by surface heating, where moisture-filled air gets pushed upwards, and orographic lifting (mountain formations) in Meghalaya. The height above sea level is also important. Most lightning happens at lower altitudes (below 1600 feet), and the frequency decreases as you go higher up the mountains, especially in North India. Finally, the study found that as farmland and cities expand, lightning activity tends to increase in those areas.
The study shows us that lightning isn't just a random event, instead, it's shaped by the landscape, the vegetation, and even human activities. Understanding these connections can guide safety measures and help farmers and city planners make informed decisions. In a broader environmental sense, recognising how land changes—like urban expansion and agriculture—affect lightning patterns can aid in managing landscapes sustainably, ensuring that economic progress doesn’t come at the cost of increased natural hazards.
This research article was written with the help of generative AI and edited by an editor at Research Matters