When lightning strikes a person, tree, or building, an enormous electrical discharge releases energy in a fraction of a second. The effects depend on how the current travels, how much energy reaches the target, and how that energy interacts with living tissue, wood, metal, concrete, and surrounding air. A person may suffer cardiac arrest or severe burns, a tree may split apart as its internal moisture rapidly heats, and a building may experience structural damage, electrical fires, or destroyed electronics.
Although lightning can be destructive, its effects are not always visible. A person can sustain life-threatening internal injuries without extensive burns, a tree can survive a direct strike, and a building can remain standing while its wiring and connected equipment suffer serious damage. Understanding what happens requires looking at how lightning moves through different materials and how its energy is transferred.
How lightning delivers its energy
Lightning begins when electrical charges separate within a thunderstorm. Interactions among ice crystals, supercooled water droplets, and other particles help create regions of positive and negative charge. As the electrical field strengthens, the difference in charge between regions of the cloud, or between a cloud and the ground, can become great enough to trigger an electrical breakdown of the air.
Air normally acts as an electrical insulator, meaning it resists the movement of electric charge. During a lightning discharge, however, the intense electric field causes air molecules to become ionized. This creates a conductive path through which electric current can flow.
In a typical cloud-to-ground flash, a developing channel of ionized air descends from the cloud in a series of steps. As it approaches the ground, an upward electrical connection may form from a person, tree, building, or another object. Once a conductive path connects the cloud and the ground, a powerful current can surge through it in a bright return stroke.
Lightning is extremely brief, but the current and energy involved can be substantial. A flash may contain multiple strokes, sometimes following the same channel. The channel itself becomes intensely hot, causing the surrounding air to expand explosively and produce the sound we hear as thunder.
Not all lightning strikes follow the same path. A direct strike occurs when the lightning channel connects with the target itself. Other dangerous forms include side flashes, in which current jumps from a nearby object to a person or another object, and ground current, in which electricity spreads through the ground after a strike. These different pathways help explain why lightning can injure someone who is not struck directly.
What happens when lightning strikes a person
A lightning strike can disrupt the heart, interfere with breathing, damage the nervous system, and cause burns. The outcome depends on the current pathway, the duration and characteristics of the discharge, the person’s condition, and how quickly emergency treatment begins.
One of the most dangerous effects is electrical disruption of the heart. The heart relies on coordinated electrical signals to control its contractions. A sufficiently powerful electrical discharge can interrupt this system, potentially causing cardiac arrest, in which the heart stops pumping blood effectively. Lightning can also stop normal breathing by disrupting the nervous system’s control of the respiratory muscles.
Cardiac arrest may sometimes resolve spontaneously after a lightning strike, but breathing problems can persist. If breathing does not resume, the lack of oxygen can cause the heart to stop again. This is one reason immediate resuscitation is so important for lightning victims.
The nervous system can sustain both immediate and lasting damage. The brain and spinal cord may be affected, leading to confusion, memory problems, weakness, numbness, chronic pain, or difficulties with concentration. Some survivors experience persistent neurological symptoms even when they have little visible evidence of an injury. The precise causes of long-term symptoms vary, and not every symptom can be attributed to a single, clearly established mechanism.
Burns are another possible consequence. Lightning may produce superficial burns, deeper tissue injuries, or distinctive skin patterns sometimes called Lichtenberg figures. These branching, fern-like marks can appear after a strike and are associated with effects on small blood vessels and skin tissues. They are not ordinary thermal burns and usually fade over time.
The absence of obvious burns does not mean a person is unharmed. Electrical effects on the heart and nervous system can be severe even when the skin appears relatively normal. Lightning may also cause muscle damage, eye injuries, hearing problems, and trauma from the force of the event or from being thrown to the ground.
How lightning current travels through the body
When lightning contacts a person, the current does not necessarily travel uniformly through the body. Some may pass over the skin, while some can travel through internal tissues or follow paths influenced by moisture, clothing, and contact with the ground.
A phenomenon known as a flashover can occur when part of the electrical discharge travels over the body’s surface rather than passing entirely through internal tissues. This can reduce the amount of current that penetrates the body, although it does not make the event safe. Internal injuries, burns, and cardiac or neurological effects can still occur.
Clothing and skin moisture may influence how the current travels, but neither offers dependable protection from lightning. The discharge can also ignite clothing or cause moisture on the skin to heat rapidly.
A person’s position relative to the strike matters as well. Someone directly connected to the lightning channel may experience different injuries from someone affected by a side flash or ground current. In a ground-current event, electricity can enter through one part of the body and leave through another, potentially crossing the heart or nervous system.
Can a person survive a lightning strike?
Yes. A lightning strike is not automatically fatal, and some survivors recover without lasting physical problems. Others experience serious or permanent complications.
Survival depends partly on whether the heart and breathing recover promptly, whether oxygen deprivation damages the brain, and whether additional injuries occur. Rapid emergency care can make a critical difference.
Anyone who has been struck by lightning or is suspected of having been struck needs immediate medical assessment. Call 911 in the United States. If the person is unresponsive and is not breathing normally, begin CPR and use an automated external defibrillator (AED) if available, following the device’s instructions and the emergency dispatcher’s guidance.
A person struck by lightning does not retain an electrical charge, so it is safe to touch them and provide first aid. If several people are injured, responders may prioritize those who are unresponsive or not breathing because prompt resuscitation may save their lives.
What happens when lightning strikes a tree
Trees are particularly vulnerable to lightning because they are tall, often contain substantial moisture, and may provide a relatively direct path between the electrical discharge and the ground. Yet the outcome varies widely. Some trees suffer little lasting damage, while others lose branches, develop deep cracks, or split apart.
One of the main mechanisms of damage is the rapid heating of water inside the tree. Wood contains moisture, especially in the living tissues beneath the bark and within the sapwood. When lightning current passes through these tissues, electrical energy can heat the water extremely quickly.
If enough water turns into steam, the resulting pressure can exceed what the surrounding wood can withstand. The bark may peel away, long strips of wood may be torn loose, or the trunk may split. This explosive mechanical damage is not caused by the lightning simply pushing the tree apart; it results largely from rapid heating and the expansion of moisture.
The current may follow different paths through the trunk. In some strikes, much of it travels along the tree’s wet outer tissues beneath the bark. In others, the discharge penetrates more deeply, damaging the trunk’s interior. The exact route depends on the tree’s structure, moisture distribution, and the electrical conditions of the strike.
Visible damage can range from a narrow scar to a shattered trunk. Bark may be stripped away along a vertical line, branches may break, and internal tissues may be damaged even when the outside looks relatively intact. Roots can also be affected as current spreads into the soil.
Why some trees survive and others split apart
A tree’s response depends on its species, size, moisture content, internal condition, and the path taken by the current. A strike that travels mainly along the outer layers may leave the trunk largely intact. A strike that rapidly heats moisture inside the wood can produce much more destructive pressure.
Trees with existing decay or structural weaknesses may be more susceptible to severe damage, although no tree can be considered immune. A tree can also survive the initial strike but decline later because damage to the living tissues beneath the bark interferes with the movement of water and nutrients.
Leaves may wilt, branches may die, and sections of the crown may gradually deteriorate. Damage to the roots can make the decline difficult to recognize at first. A tree that appears healthy immediately after a strike may therefore develop problems over weeks or months.
Lightning can also injure or kill wildlife sheltering in a tree. Current may travel through branches and the trunk, then spread through the surrounding ground. Animals or people near the base can be affected even if the main channel never touches them directly.
A damaged tree may pose a separate danger after the storm. Cracked trunks, weakened branches, and injured roots can make it unstable. People should avoid climbing or cutting a lightning-damaged tree until its condition has been assessed by someone qualified to evaluate tree hazards.
What happens when lightning strikes a building
Buildings can be struck directly by lightning, but they may also experience damage from nearby strikes. The effects depend on the building’s height, construction, electrical systems, grounding arrangements, and lightning-protection features.
A direct strike can damage a roof, chimney, antenna, or other exposed structure. The intense heat may ignite combustible materials, while the electrical current can travel through conductive components toward the ground. If the current encounters a path that cannot safely carry it, electrical arcing may occur, potentially damaging materials or starting a fire.
A building does not need to catch fire or suffer visible structural damage to experience a serious strike. Lightning can induce large voltage surges in electrical wiring, communication cables, antennas, and other connected systems. These surges can destroy electronic equipment, damage appliances, and disrupt computer networks or control systems.
Even when lightning strikes outside a building, a nearby discharge can generate rapidly changing electromagnetic fields. These fields can induce voltages in conductors, sending unwanted electrical energy into equipment. A strike to a utility line or another connected system can also carry a surge into a building from a distance.
Why metal does not automatically attract lightning
Metal objects do not create thunderstorms or attract lightning from unlimited distances. Lightning is more likely to connect with objects that help establish a conductive path between the developing lightning channel and the ground. Height, location, and the local electric field influence which objects become part of that path.
Metal is highly conductive, so it can carry electrical current efficiently. That property makes metal useful in a properly designed lightning-protection system, but it does not make an unprotected metal object inherently safe.
A lightning rod, also called an air terminal, is part of a system intended to intercept a strike and conduct the current along a controlled route. Conductors connect the air terminals to grounding components that disperse the current into the earth. The system must be properly designed and installed to reduce the risk of fire and dangerous electrical side effects.
The purpose of a lightning-protection system is not to guarantee that a building will never be struck. It is to provide a safer path for the current and reduce the likelihood of damage. Electrical surge protection can offer additional protection for equipment, but it serves a different function from the external lightning-protection system.
Can lightning damage concrete, brick, or wood?
Yes. The effect depends on the material and how the electrical current travels through it.
Wood can ignite or split if the discharge heats it sufficiently. Brick and concrete are not perfect electrical insulators, particularly when they contain moisture or connect to conductive materials. Rapid heating can damage them, and current may cause cracking or localized spalling, in which fragments of a surface break away.
Reinforcing steel, metal pipes, electrical wiring, and other conductive elements can provide pathways for current. If electrical energy jumps between components or reaches combustible materials, it can cause damage even when the main building structure remains intact.
A lightning strike may therefore leave a building standing while damaging its wiring, plumbing connections, roof materials, or electronic systems. After a suspected strike, signs such as smoke, burning smells, damaged wiring, or unusual electrical behavior warrant caution and professional inspection.
Why lightning affects people, trees, and buildings differently
The main differences come from how each target conducts electricity, contains moisture, and responds to rapid heating.
In a person, the most urgent danger is disruption of vital biological systems. Electrical currents can interfere with the heart and nervous system, while heating and mechanical effects can injure tissue. The damage may be life-threatening even when it is not visible.
In a tree, moisture inside the wood can rapidly turn to steam, creating pressure that tears apart bark and wood fibers. Damage to living tissues may also interfere with the tree’s ability to transport water and nutrients, causing delayed decline.
In a building, lightning current may travel through conductive structural components, wiring, plumbing, or dedicated protection systems. Rapid heating can ignite materials or damage surfaces, while electrical surges can destroy equipment.
The electrical discharge is the common cause, but the consequences depend on the target’s physical and biological properties. This is why a single lightning flash can cause a person to suffer cardiac arrest, split a tree trunk, and damage a building’s electrical systems through different mechanisms.
How lightning current spreads beyond the point of impact
Lightning is dangerous not only where it makes contact but also along the paths its current follows afterward. The current must move through the surrounding environment, and it can branch into multiple pathways.
Ground current is a major example. When lightning strikes the ground or an object connected to it, electrical potential can vary across the surface. Current may then flow through the soil and through objects or people in contact with different points. A person can be injured even if the lightning channel strikes a nearby tree or the ground rather than their body.
Side flashes are another possibility. If lightning strikes a tall tree or another object near a person, some current can jump through the air to the person when the electrical potential difference becomes large enough. This is one reason standing beneath a tree during a thunderstorm is dangerous.
Lightning can also travel along fences, pipes, cables, and other conductive pathways. The presence of metal does not mean that every nearby object will carry a dangerous current, but conductive connections can allow electrical energy to spread well beyond the original contact point.
These pathways make distance and shelter important considerations. Being indoors in a substantial, fully enclosed building generally offers much better protection than remaining outside, but people should avoid contact with wired electrical equipment, plumbing, and other conductive systems during a thunderstorm.
How to reduce the risk of lightning injury and damage
The safest response to a thunderstorm is to seek shelter before lightning approaches. A substantial enclosed building or a hard-topped, fully enclosed vehicle is generally a safer choice than an open shelter, a tent, or a spot beneath a tree.
Outdoors, avoid isolated trees, exposed hilltops, open fields, bodies of water, and other locations where you may become the most exposed object. If you hear thunder, lightning is close enough to pose a danger. Move toward appropriate shelter rather than waiting for rain or a direct strike to become likely.
Inside a building, stay away from plumbing, wired electrical equipment, windows, and exterior doors during the storm. Avoid showering or washing dishes while lightning is nearby because plumbing can provide a conductive path. Unplugging sensitive equipment before a storm arrives can reduce exposure to some surges, but do not attempt to unplug devices once lightning is already nearby if doing so requires touching electrical connections.
For buildings in exposed locations, properly installed lightning-protection systems and suitable surge protection can reduce specific risks. These measures complement, rather than replace, safe behavior during thunderstorms.
A useful general rule is to remain in a safe shelter until at least 30 minutes after the last thunder is heard. Lightning can occur before a storm’s heaviest rain arrives and can strike outside the area experiencing rainfall.
What lightning reveals about electricity and the natural world
Lightning illustrates how electrical energy can transform its surroundings through several mechanisms at once. It heats materials, creates intense pressure through rapid expansion, generates electromagnetic fields, and drives current through conductive paths. The resulting damage depends on how those effects interact with the target.
For people, the critical consequences are electrical disruption of the heart and nervous system, burns, and other trauma. For trees, rapid heating of internal moisture can tear apart wood and damage living tissues. For buildings, current can ignite materials, damage structures, and send destructive surges through electrical systems.
The same discharge can therefore produce very different outcomes. Some injuries and damage are immediately obvious; others emerge only later. Recognizing these differences helps explain both the power of lightning and the importance of taking thunderstorms seriously.