Lightning

Lightning can be defined as a transient, high-current (typically tens of kiloamperes) electric discharge in air whose length is measured in kilometers. As for any discharge in air, lightning channel is composed of ionized gas, that is, of plasma, whose peak temperature is typically 30,000 K, about five times higher than the temperature of the surface of the Sun. Lightning was present on Earth long before human life evolved and it may even have played a crucial role in the evolution of life on our planet. The global lightning flash rate is some tens to a hundred per second or so. Each year, some 25 million cloud-to-ground lightning discharges occur in the United States, and this number is expected to increase by about 50% due to global warming over the twenty-first century. Lightning initiates many forest fires, and over 30% of all electric power line failures are lightning related. Each commercial aircraft is struck by lightning on average once a year. A lightning strike to an unprotected object or system can be catastrophic. In this chapter, an overview of thunderclouds and their charge structure is given, basic lightning terminology is introduced, and different types of lightning (including the so-called rocket-triggered lightning) are described. For the most common negative cloud-to-ground lightning, main lightning processes are identified and the existing hypotheses of lightning initiation in thunderclouds are reviewed. Additionally, current and electromagnetic field signatures of lightning are characterized and the techniques to measure lightning electric and magnetic fields are discussed.

This chapter is concerned with the remote detection and analysis of thunderstorms and lightning flashes by electrostatic, electromagnetic and photographic means, and the use of these methods for public warning of hazardous conditions. Section 1 addresses the measurement of electrostatic fields in fair weather and in response to the stronger fields of electrified shower clouds and thunderstorms. Section 2 reviews various methods in place worldwide for the detection of the electromagnetic radiation from lightning. The observation of the evolution of lightning flashes with video-camera observations is the subject of Sect. 3. The final Sect. 4 addresses the dissemination of the multitude of available observations for purposes of improving lightning safety.

It is frequently needed to analyze the possible damages caused by lightning to a structure and its connected lines and evaluate their frequency of occurrence as well as the extent of the associated damages. The method to perform this is named Lightning Risk Assessment and is based on an IEC Standard 62305-2 that is based on a methodology with 25 years of experience. This analysis will aim to determine what is the most efficient protection strategy, where to install the selected lightning protection components and with which rating. Lightning may cause many types of damages to a structure. They are usually named “losses” and there are four types of losses: loss due to injury to human beings, loss due to physical damage of the structure and its contents, loss due to failure of internal systems and loss of economic value including cost to repair and production loss. To each of this loss is associated a risk and there are then a maximum of four risks that can be calculated. Four sources of damage are considered in the calculation of the risk: lightning flash to the structure, lightning flash near the structure, lightning flash to the connected lines and lightning flash near the connected lines. Risk component are related to the sources of damage as well as to the type of losses. There is a maximum of eight risk components to calculate, the risk being the sum of the considered components. Each risk component is calculated in the same way as a multiplication of the number of events by the probability this event creates a damage and by the amount of damage generated. The number of events depends on the structure or lines dimensions and parameters and also on the severity of the area in terms of lightning flashes per year and per km². The probability this event creates a damage is related to the resilience of the structure and its contents and connected lines, to a lightning event as well as lightning protection measures such as lightning rods or Surge Protective Devices. Then the amount of damage generated, can be calculated based on the existing mitigating measures (for example fire detection) and to the time of presence of people in a dangerous zone inside the structure. When the appropriate risk components are calculated, the risk can be evaluated as a sum of these components and compared to a tolerable risk level. If the calculated risk is lower than this tolerable level, no additional lightning protection measures are needed and the level of risk can be accepted. If this is not the case, lightning protection measures should be added until the risk decreases below the tolerable level. The efficiency of the protection measures is related to a level of protection ranging from IV to I, I being the best that defines the percentage of cases for which the structure will be protected. Of course, a Lightning Protection System at level I will cost more than at level IV and a specific economic risk method is proposed for evaluating the cost/benefit of these measures. To collect the input parameters that are required for a proper evaluation of the risk level, needs time and shouldn’t be under estimated, especially for old structures for which documents may not exist anymore or complex cases such as a factory where many lines are connected to a structure. For a few cases, simplified methods have been developed to avoid the burden of collecting all these parameters.

So often standards and norms do not spell out exactly what it recommends, leaving the reader unsure about where to start, what the next steps are in order to design and install a lightning protection system. The spirit of this chapter is one of cookbooks, containing cost-effective recipes together with clear step-by-step guides to practically cook up a lightning protection system for a building and or structure, which is both safe and effective.

This chapter describes the main aspects related to the protection of electrical equipment and low-voltage systems. It initially addresses the way lightning surges can occur in such systems—they can be induced by lightning strikes inside the clouds, or between different clouds; those conducted by low-voltage network conductors due to direct lightning strikes; surges from lightning strikes on medium-voltage networks; discharges that reach points near networks and are, therefore, induced in low-voltage systems; discharges that reach the LPS (Lightning Protection Systems) and return to the systems by the MEB (Main Earthing Busbar), and those induced in low-voltage systems by lightning strikes through the LPS conductors are also analyzed. The chapter details the main surge protection measures, such as earthing and bonding, shielding, routing, surge protection devices coordination, and isolating interfaces. The chapter defines the concept of Lightning Protection Zone (LPZ) for the positioning of Surge Protection Devices (SPD) and specified and detailed, types and characteristics of these devices. The chapter also covers grounding concepts, resistance and resistivity measurements, and describes the main elements and use of the earth-termination system.

Petrochemical plants are outdoor facilities that hold and produce vast quantities of chemicals. Critical stages of production deal with toxic, flammable and explosive substances. The petrochemicals industry sources raw materials from refining and gas-processing and converts these raw materials into valuable products using a variety of chemical process technologies. Historically the industry evolved out of technological innovation in the developed industrialised economies. Until the last quarter of the twentieth century production of petrochemicals was concentrated in Western Europe, the United States and Japan. Over the last few decades, however, production in areas with competitively priced feedstocks has increased dramatically. New production capacity has been built in the Middle East and Asia, and lightning strikes can be a major hazard.

The lightning protection and the surge protection of large ground-mounted photovoltaic power plants as well as of small roof-mounted photovoltaic systems is considered. Basics for external and internal lightning protection as well as special requirements, especially for surge protection, are presented. The measures result from experiences in the last years, are today recognized widely and are realized to a large extent. Lightning and surge protection of wind turbines has received increasing attention in recent decades due to considerable damage caused by direct lightning strikes. Today, onshore and offshore wind turbines are equipped with lightning protection systems according to the highest level of lightning protection and the declining damage shows the effectiveness of the measures. Special attention is paid to the protection of the rotor blades. But also surge protection for electrical energy and information technology systems including EMC measures is of great importance and is described. Many specialities have to be taken into account in the lightning and surge protection of wind turbines. For railway facilities and systems, national and international comprehensive concepts for lightning and surge protection have hardly been described. The considerations and measures presented here also do not claim to be complete, but are intended to address important aspects. These include above all measures for the protection of control and command technology systems as well as information on personal protection. In addition, lightning and surge protection of the power supply, measurement systems and EMC measures are addressed.

Lightning deaths and injuries have greatly been reduced in both number and population-weighted rate in more developed countries in the last few decades. However, this reduction has not taken place in many developing nations. The most important factor affecting lightning casualties is not an excessive occurrence of lightning, although this is often a contributor, but the vulnerability of people in developing nations. In these locations, people continue to rely on subsistence agriculture and have no lightning-safe buildings or vehicles nearby, a poor understanding of lightning, weak medical systems, and no access to lightning data in real time. Although direct strike is often considered the most common mechanism of injury, it is quite rare. Instead, ground current, side flash, upward leader, and direct contact are more common. Injuries are commonly related to cardiac issues and neurologic impacts rather than burns which are usually less consequential. Medical treatment at the time of a mass casualty event should concentrate on those who appear to be dead, and CPR can be lifesaving. Long-term sequelae are often permanent and difficult to manage without substantial intervention which is usually not available in developing areas.

Being a spectacular atmospheric phenomenon, lightning could induce significant interest in the human mind since the beginning of history. Most often the public perceptions of many communities about lightning were marked by divinity, power, fear and punishment. The belief systems extend up to the present time, despite the development of modern science and technology. In the last two centuries, the scientific understanding of the thunderstorm and lightning phenomena gradually improved and at present we have a significant awareness of the nature of lightning, injury mechanisms and lightning-related medicine. The modern safety guidelines and safety modules for communities in lightning-dense geographical areas are based on proven scientific facts. In several developed countries, a marked decrease in the number of lightning casualties could be observed during the past century, due to the continuous safety awareness programs. However, lightning safety modules which are highly successful in one part of the world may not be that successful in another part of the world.

Despite the significantly large number of deaths and injuries, the property loses and service downtime, lightning is not treated as a serious natural hazard in many countries of which lightning ground flash density is notably high. In this chapter, we highlight this lack of attention from both government and non-governmental sectors as a substantial barrier to curb lightning related losses. The ignorance of experts and statutory bodies that control the implementation of standards and guidelines have paved the way to the flooding of fraudulent products and technologies into the respective countries. The attitudinal issues and negligence of responsibilities of engineering and managerial capacities of both private and government sectors contributes to the mishaps and losses due to lightning-related incidents. The chapter finally discusses possible mechanisms of promoting lightning protection as business ventures in less-privileged communities by developing entrepreneurship among people having low to medium levels of technical know-how.

Lightning research has been playing an important role for decades in the scientific community. Lightning researchers have been putting a huge effort into solving issues in electromagnetic modeling, instrumentation, and the analysis of large datasets. Scientists from developing countries are in constant  improvement of their techniques for lightning research because they need to do more with fewer resources. In this chapter, we discuss a brief history of lightning research to understand at which point we are now. After that, it is shown the main topics of lighting research that, the most relevant journals published at the beginning of the XXI century. Later, it is discussed some studies that were carried in developing countries including Brazil, Colombia, India, Malaysia, South Africa, and Sri-Lanka, that are the more prominent developing countries in lightning research. In the end, it is discussed the frontiers in lightning research for developing countries, which it is addressed the use of artificial intelligence in lightning research.