INTRODUCTION:

Lightning is a giant spark of electricity in the atmosphere. It is the process in which natural electrical discharge occurs in very short duration and high potential difference between a cloud and ground or within a cloud generates along a bright flash and sound. Intracloud lightning commonly known as cloud discharge is visible but harmless. The cloud -to-ground lightning discharge is harmful, as they move downward from cloud. About 90% of such discharge is initiated by negatively charged leader and they bring tens of coulombs of negative cloud charge to the earth. Cloud-to-ground discharge is result of the difference in electrical charge between the top and the bottom regions of a cloud. Positive charges accumulate at the top and negative charges at the bottom of the cloud. The rising and descending of air within the clouds, separates positive and negative charges. Due to this separation of charges within the cloud an electric field is generated which allow the electric spark to jump across the air gap. The discharge within the cloud prior to stepped leader is called” Preliminary Breakdown”. After Preliminary breakdown, the first main cloud-to-ground discharge begins and the negative charge moves towards the ground in the steps. This first stroke is called Stepped Leader. The electric field produced by the charge on the leader enhance when some conducting object comes in its path. This field enhancement may cause upward electric discharge. When one of the upward moving discharge from the ground contact the downward moving leader, at some tens of meters above the ground, the leader tip is connected to the ground potential. The leader channel is then discharged, the return stroke propagates up the previously ionized leader path. After the first set of stepped leaders and return stroke, leader process again starts from the cloud. As the air column below is already partially ionized, the leader reaches the ground almost in a single or two steps. This is called dart leader. Thus, the return strokes subsequent to the first in a flash to ground are usually initiated by dart leader. The total all lightning strokes from a region in the cloud is called lightning flash. Lightning flash thus consist of the initial return stroke and all subsequent return strokes. The stepped leader and dart leader light travel from cloud to ground while the return stroke light travels from ground to cloud.

REVIEW LITERATURE:

Lightning has a greater probability of striking raised objects on the ground such as tall trees, multistorey buildings or transmission towers. It has been observed that about 70% of lightning strikes occur on land in the tropics. The North and South poles and the Oceans have the fewest lightning activities. It has been observed by several researchers that some regions are notably prone to thunderstorms and electrical discharge, while other have practically none. The regions located between the equator and the northern and southern 38^th parallel are prone to the most lightning activities. Brook (1925), estimated first global lightning flash rates were 100 flashes per second based on an average number of lightning flashes per storm and thunderstorm counts were recorded by several surface weather stations. Boccipio et al. (2000); Willams et al. (2000); Christan et al. (2003); Albrect et al. (2014) and many other researchers studied that in subsequent years, human observers, individual flash counters and finally Earth- orbiting instruments were used to estimate global flash rates. Court and Griffiths (1982) found that Uganda followed by the Democratic Republic of the Congo and Rwanda are the place with more thunderstorm per day and unfortunately, they did not have data from Venezuela. Rachel et al. (2016) in their study observed that the region with most lightning strikes is lake Maracaibo in Venezuela, not the eastern Congo Basin in Africa. They studied that the earth’s top ranked lightning activity occurs over lake Maracaibo in Venezuela where lightning occurs 297 days per year with a peak in September month. Cadozzi (1841) studied that the thunderstorms over lake Maracaibo are so frequent that these thunderstorms are known as the” Light house of Catatumbo”, Catatumbo is a river that ends southwest of Maracaibo Lake. The lake is connected to the Gulf of Venezuela at its northern end, near Maracaibo city. Munoz et al. (2008) explained that the warm water of temperature about 28 to 31 degrees Celsius over the lake and at the gulf, throughout the year serve as a source of heat and moisture for convection. All geographical conditions combined with wind flow over this warm, humid lake make a favorable circumstance for thunderstorm development.

The five regions with most electrical discharge on each continent and other regions as studied by several researchers and Rachel et al. (2016), despite of global warming is not changed significantly. They are discussed below;

As studied by researchers in South America, there are five hotspots with higher rate of lightning strikes. These are distributed over Colombia and Venezuela. Rachel et al. (2016) found that Lake Maracaibo is the region with most lightning in the world, with 233 lightning strikes per km square per year. Lake Maracaibo in Venezuela, is the largest inland water body in South America. Lightning illuminates the lake at the spot where the Catatumbo river flows into the lake up to 260 nights per year with up to 60 flashes per minute. Other hotspots of lightning strikes in South America are in Colombia. The frequency of lightning strikes in the regions of foothills of northern Andes massif is very high as compared to other parts of the world. The city of Teresina in northern Brazil has 3^rd highest rate of occurrence of lightning strikes in the world.

The most lightning strikes about eight of the ten regions in Africa are in the Democratic Republic of Congo, with up to 205 lightning strikes per km square per year, the second ranked lightning hotspot on the earth is at Kahuzi-Biega National Park, near the city of Kabare in Democratic Republic of the Congo on the west side of the Mtumba Mountains. Ngutic in Cameroon in Africa is the 4^th most thunderstorm prone region. In West and Central Africa most thunderstorms are most active between September and May.

In North America, the 1^st and 2^nd hotspot Patalul and Catarina are in Guatemala. These two regions where the most lightning activity occurs are located at the foot of a mountain range, the Sierra Madre. These regions show lighting activity during the afternoon during spring and summer seasons. The lightning strikes were recorded up to 117 and 103 per km square per year in both regions. In the United States, the lightning hotspot is in the Everglades, near orange tree, Florida. Florida has the largest number of lightning strikes during summer. Much of Florida is a Peninsula, bordered by the Ocean on three sides with a subtropical climate. The result of which is daily development of clouds that produce thunderstorms and promote electrical discharge.

The most thunderstorm occurring in the three regions in Asia are in Pakistan, are Northern Punjab, Khyber Pakhtunkhwa and Azad Kashmir. These regions are located at the foot of the Himalayas have the greatest amount of lightning activity during the monsoon months and activity during the monsoon months and especially in August and September. A violent thunderstorm with intense lightning activity develops in the Daggar in Hindu Kush foot hills in July and Kashmir, violent thunderstorms with tornadoes, heavy hail storms and flooding are observed during monsoon season. Kuala Lumpur the capital of Malaysia also has interesting lightning climatology. Its ranks 10^th in Asia, with 93 lightning strikes per km square per year, but it is the world’s most lightning prone capital city. Malaysia and Singapore have highest rates of lightning activity in the world, after Indonesia and Colombia.

Oceania hotspots are found at the northern coast of Australia. The four most lightning prone regions with intense lightning activity are in the northern Australian coast. Oceania’s top lightning activity occurs in Derby, Australia within a flat coast region mostly in afternoon during summer season. The fifth most lightning prone region of continent Oceania is in Papua New Guinea where lightning generally occurs during summer monsoon.

Key Factors Contributing to the Rising Incidence of Lightning Strike:

The increasing frequency and severity of thunderstorms and lightning activity is attributed to climate change, urbanization, global warming, deforestation and changes in weather pattern. The factors influencing the lightning incidents as studied by serval researchers are discussed below:

Climate change:

Global warming and climate change potentially influence atmospheric conditions, which increases electrical activity. IITM (Indian Institute of Tropical Management) studies concluded that the increase in lightning strikes is directly related to the climate crisis. As the temperature of planet rises, it may mark considerable change in the availability of moisture and convective processes, which favor more frequent lightning incidents. California University published a study in 2015, which warn that an increase of one-degree Celsius temperature would increase frequency of lightning strikes by 12%. A study published in Geophysical Research Letter in March 2021, has also found links between climate change and rising incidences of lightning in the Artic region.

Urbanization:

It has been studied that city have higher temperature than surrounding rural areas due to increased human activities, less trees and less cooling effect of transpiration. The expansion of urban areas creates Urban heat island effect, which leads to the formation of more thunderstorms and consequently an increase in lightning strikes.

Deforestation:

It is very well known that deforestation and alterations of natural landscapes disturb the atmospheric conditions. These significant changes highly contribute to the development of thunderstorms and consequently results more lightning incidents. Trees help to add moisture to the atmosphere so deforestation reduce the moisture and increase the temperature which consequently increase the frequency of lightning activities.

Pollution:

Air pollution, including aerosols can affect cloud formation and lightning activities. It has been studied that pollution affect the distribution of cloud particles, which increases cloud-to-ground lightning. Also, it has been concluded by the study of several researchers that urban pollution can increase thunderstorms and lighting in many parts of the world.

CONCLUSION:

Earth’s lightning flash activity areas and frequency have been a subject of interest and study for decades. It has been observed that lightning activity varies globally, with some regions experiencing much higher frequencies than other. The distribution of lightning exhibits a factors like climatic, geographic and weather conditions. The highest frequencies of lightning are found in areas with high levels of atmospheric moisture and instability. The lightning activities in mountain regions are influenced by topography, enhancement of thunderstorms which leads to increased frequencies of lightning. The distribution of lightning has significant implications for weather forecasting, climate modeling and risk assessment. Future research should focus on development of more advanced lightning forecasting models to provide timely warning for lightning to avoid lightning related hazards.

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Received on 11.01.2025 Revised on 28.01.2025

Accepted on 12.02.2025 Published on 10.03.2025

Available online from March 21, 2025

Research J. Science and Tech. 2025; 17(1):73-76.

DOI: 10.52711/2349-2988.2025.00010

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