Lightning is a giant electric spark that jumps inside a storm cloud, between two clouds, or from a cloud to the ground. The spark heats the air to about 50,000 °F (28,000 °C), which is about five times hotter than the surface of the Sun. Around the world, lightning flashes about 44 times every second.
Why lightning is so wild
Lightning starts inside a tall, puffy storm cloud called a cumulonimbus. Inside the cloud, tiny ice crystals and bigger soft hail balls called graupel bump into each other. The bumping rubs electric charges off, kind of like when you scuff your socks on a carpet and then touch a doorknob. Positive charges pile up near the top of the cloud, and negative charges sink to the bottom. When the difference gets big enough, the air can’t hold the charges apart anymore, and a giant spark jumps. That spark is lightning.
The flash you see is so bright because the air inside it gets hotter than the Sun. The crackle and boom you hear is thunder. Thunder is the sound of air exploding outward as the lightning channel heats up so fast.
Key facts about lightning
A lightning bolt heats the air to about 50,000 °F (28,000 °C). That is roughly five times the temperature of the Sun’s surface.
A typical bolt carries about 30,000 amps of electric current. A normal house outlet carries about 15 amps.
One bolt can have 100 million to 1 billion volts. A flashlight battery has 1.5 volts.
Earth gets about 44 lightning flashes every second. That works out to about 3.8 million flashes a day, or roughly 1.4 billion a year.
A cloud-to-ground lightning bolt is usually 2 to 3 miles long (3 to 5 km), but the longest ever measured stretched 515 miles (829 km) across the southern United States in October 2017.
The fast bright streak going up the channel, called the return stroke, moves at about 200 million miles per hour. That is about one-third the speed of light.
Light travels much faster than sound, so you see the flash first and hear the boom later. Every 5 seconds between the flash and the thunder means the lightning was about 1 mile (1.6 km) away.
Thunder is the sound of the air exploding outward when lightning heats it up.
About 20 people in the United States are killed by lightning each year, and a few hundred more are hurt. Almost all of those people were outside when it happened.
A park ranger named Roy Sullivan was hit by lightning seven times and survived every strike. Guinness World Records lists him as the person hit by lightning the most times.
Common myths about lightning
Myth: Lightning never strikes the same place twice. It does, all the time. The Empire State Building in New York City gets hit about 25 times every year on average.
Myth: If it is not raining where you are, you are safe. Lightning can travel sideways through the air and hit the ground more than 10 miles (16 km) from the storm cloud. People call these strikes “bolts from the blue” because the sky right above can look clear.
Myth: Rubber shoes or rubber tires will save you. They do not give meaningful protection. A car keeps you safer because the metal frame guides the electricity around the outside, not because of the tires.
Myth: You should hide under a tree. A tall tree alone in a field is one of the worst places to stand. Lightning often strikes the tallest object in an area, and the current can jump from the tree into anyone nearby.
Myth: Touching someone who was hit will shock you. A person who has been struck does not hold any electric charge afterward. It is safe to help them, and fast help can save a life.
Frequently asked questions
How hot is lightning? A lightning bolt heats the air around it to about 50,000 °F (28,000 °C). That is about five times hotter than the surface of the Sun, which is about 10,000 °F (5,500 °C).
How long is a lightning bolt? A regular cloud-to-ground bolt is 2 to 3 miles long (3 to 5 km). The longest one ever measured by satellites was 515 miles (829 km) across the southern United States in October 2017.
Why do I see lightning before I hear thunder? Light travels almost instantly, so the flash reaches your eyes right away. Sound is much slower, so the boom takes time to reach your ears. Every 5 seconds of delay equals about 1 mile (1.6 km) of distance.
What should I do in a thunderstorm? Go inside a real building or a car with a hard roof. Stay there until 30 minutes after the last clap of thunder. The National Weather Service rule is short and easy: when thunder roars, go indoors.
Can you survive being struck by lightning? Yes. About 9 out of 10 people who are struck survive, though many have lasting injuries. Quick help, including CPR if needed, makes survival much more likely.
Where on Earth does lightning happen the most? Over Lake Maracaibo in Venezuela. The skies there flash with about 250 lightning bolts per square kilometer (per about 0.4 sq mi) every year, more than any other place on the planet.
Source notes
The numbers in this article come from the National Oceanic and Atmospheric Administration (NOAA), the National Weather Service, NOAA’s National Severe Storms Laboratory, and the World Meteorological Organization, which keeps the official world records for lightning. The Guinness World Records entry for Roy Sullivan is based on records kept by Shenandoah National Park during his time as a ranger there. Full source links sit in this article’s frontmatter for anyone who wants to read further.
Lightning is a sudden electric discharge that releases the charge built up inside a thunderstorm. Each flash heats the surrounding air to roughly 50,000 °F (28,000 °C), which is about five times the temperature of the surface of the Sun. NASA satellites count about 44 lightning flashes per second worldwide, or roughly 1.4 billion every year.
Why lightning is more interesting than it looks
A single bolt of lightning looks instantaneous, but it has several pieces that happen in order. First, charge builds up inside a tall thunderstorm cloud, a cumulonimbus. Inside that cloud, soft hail particles called graupel collide with smaller ice crystals. The collisions strip electrons from one and stick them onto the other, similar to the way socks and a carpet trade electrons when you walk across the room. The lighter ice crystals get carried up to the top of the cloud as positive charge, and the heavier graupel drifts toward the middle and bottom carrying negative charge. The cloud ends up acting like a battery with a positive top and a negative bottom.
When the charge difference becomes large enough to overpower the air’s resistance, a faint, branching trail of charge called a stepped leader works its way down toward the ground in 50-meter (about 150 ft) jumps. As it nears the ground, positive streamers reach up from tall objects to meet it. The moment they connect, current rips back up the channel as a return stroke at about one-third the speed of light. That return stroke is the bright flash you see. The whole sequence takes a small fraction of a second.
Key facts about lightning
The lightning channel reaches about 50,000 °F (28,000 °C). That is roughly five times the temperature of the visible surface of the Sun, which sits near 10,000 °F (5,500 °C).
A typical lightning flash involves about 300 million volts and a peak current near 30,000 amps. Some flashes carry 100 million to 1 billion volts.
Stepped leaders descend at about 200,000 mph (320,000 km/h). The return stroke that follows races back up at about 200 million mph (320 million km/h), close to one-third the speed of light.
About 44 lightning flashes hit Earth every second. That averages out to roughly 3.8 million flashes a day, or 1.4 billion a year.
Most lightning never reaches the ground. NOAA estimates intracloud and cloud-to-cloud flashes outnumber cloud-to-ground flashes by 5 to 10 times.
About 5 percent of cloud-to-ground bolts carry positive charge instead of negative. Positive bolts often start in the upper anvil of the storm and tend to be stronger and longer than negative ones.
The longest single lightning flash on record stretched 515 miles (829 km) across the southern United States on October 22, 2017. The longest one in duration lasted 17.1 seconds over Argentina and Uruguay on June 18, 2020. Both records were certified by the World Meteorological Organization, with the distance record certified in 2025 after detailed satellite reanalysis.
Lake Maracaibo in Venezuela hosts more lightning per area than anywhere else on Earth, about 250 flashes per square kilometer (per about 0.4 sq mi) each year.
Thunder is the shock wave from air that expands explosively when the lightning channel heats it. Sound takes about 5 seconds to travel 1 mile (1.6 km), so the gap between flash and thunder gives you a quick distance estimate.
About 20 people in the United States die from lightning each year, and roughly 270 are injured. Around 9 in 10 victims survive, though many face long-term health problems.
Common myths about lightning
Myth: Lightning never strikes the same place twice. Tall structures get hit many times each year. The Empire State Building averages about 25 strikes every year, and tall radio masts get hit on a regular schedule during storms.
Myth: If you are not standing in the rain, you are safe. Lightning can leap from the cloud’s anvil and strike ground more than 10 miles (16 km) from the storm core, sometimes under skies that look clear directly overhead. Forecasters call these “bolts from the blue.”
Myth: Rubber-soled shoes or car tires protect you. A few millimeters of rubber is no match for a billion-volt discharge. A car protects you because the metal frame guides current around its outer skin and into the ground, not because of the tires.
Myth: A tree is good shelter. Lightning often strikes the tallest object in an area, and once it reaches the trunk, the current can jump sideways to people standing under the branches. NWS calls this side-flash.
Myth: Lightning comes only from the bottom of the cloud. Plenty of lightning travels between clouds, inside a single cloud, or out of the high cirrus anvil. About 5 percent of cloud-to-ground bolts originate in the upper, positively charged anvil.
Myth: A person struck by lightning is dangerous to touch. People do not stay charged after a strike. CPR and immediate medical help save lives, so do not hesitate to act.
Frequently asked questions
What is lightning, exactly? Lightning is an electric discharge that suddenly equalizes the charge difference between two regions of a thunderstorm, between two clouds, or between a cloud and the ground. The flash is the heated channel of air glowing as it carries the current.
Why is lightning hotter than the Sun? The lightning channel briefly reaches about 50,000 °F (28,000 °C) because a huge amount of electrical energy is dumped into a thin column of air in a few millionths of a second. The Sun’s surface is much larger but stays around 10,000 °F (5,500 °C). The difference is concentrated power, not total energy.
What causes thunder? The lightning channel heats the air so fast that the air expands faster than the speed of sound, producing a shock wave. That shock wave decays into the rolling sound called thunder. The rumble you hear stretches out because parts of the channel are at different distances from your ears.
Where does lightning happen most often? Over land in the tropics. Africa’s Congo Basin, parts of South America, and the Caribbean coast of Venezuela hold the highest flash densities. Lake Maracaibo’s “Catatumbo lightning” averages about 250 flashes per square kilometer per year, the highest density anywhere on Earth.
How is the longest lightning flash measured? Satellites called Geostationary Lightning Mappers, on the GOES-16 and GOES-17 spacecraft, photograph lightning from above the clouds. They can track a single flash that branches across hundreds of miles. The current distance record certified by the World Meteorological Organization is 515 miles (829 km).
What should I do if a thunderstorm catches me outside? Get inside a closed building or a hard-topped vehicle as fast as possible, and stay inside until 30 minutes after the last thunderclap. Avoid open fields, water, tall isolated trees, and anything metal. The National Weather Service slogan sums it up: when thunder roars, go indoors.
Source notes
The lightning physics in this article follows the National Weather Service’s Understanding Lightning series and the National Severe Storms Laboratory’s Severe Weather 101 chapter. The world records for flash distance and duration come from World Meteorological Organization certifications, including the current distance record (829 km / 515 mi) certified in 2025 from a 2017 megaflash, both based on data from NOAA’s Geostationary Lightning Mapper. The flash density figure for Lake Maracaibo comes from NASA Earthdata’s writeup of the Lightning Imaging Sensor results. Direct links to all of these are listed in this article’s frontmatter.
Lightning is a transient, high-current electrical discharge that occurs when accumulated charge in the atmosphere overcomes the dielectric strength of air. Most lightning happens within a single cumulonimbus cloud or between two clouds; only about one in every five to ten flashes connects to the ground. NASA’s Optical Transient Detector and Lightning Imaging Sensor data put the global flash rate near 44 flashes per second, totaling roughly 1.4 billion flashes per year.
Why lightning rewards a closer look
A typical thundercloud organizes itself into a tripole charge structure: a strong negative layer in the middle, a positive layer above it, and a smaller positive pocket near the cloud base. This separation is driven by the noninductive charging mechanism. Inside the mixed-phase region of a cumulonimbus, where temperatures sit between roughly 5 °F and minus 13 °F (about minus 15 °C and minus 25 °C), riming graupel collides with smaller ice crystals. Above a critical temperature, charge transfer leaves the ice crystals positively charged and the heavier graupel negatively charged. Updrafts then sort the particles by mass: ice crystals rise, graupel sinks, and the cloud builds a vertical electric field that can exceed several hundred kilovolts per meter.
Once the field is strong enough to ionize a path through the air, a stepped leader propagates downward in roughly 50-meter (about 150 ft) increments at an average speed near 200,000 mph (320,000 km/h). Branches reach toward upward-traveling positive streamers from elevated objects on the ground. Connection establishes a conductive channel; the return stroke then travels back up that channel at approximately one-third the speed of light, about 200 million mph (320 million km/h). The channel briefly heats to about 50,000 °F (28,000 °C), explosively expanding the surrounding air and producing thunder. Subsequent dart leaders can reuse the same channel within tens of milliseconds, producing the flicker effect that the eye perceives.
Key facts about lightning
Channel temperature reaches about 50,000 °F (28,000 °C) in the return stroke, roughly five times the temperature of the visible solar surface (about 10,000 °F or 5,500 °C).
A typical cloud-to-ground flash carries about 30,000 amps of peak current and a potential difference of roughly 300 million volts. The full range across all flashes spans 100 million to over 1 billion volts.
The stepped leader descends at average speeds near 1 × 10⁵ m/s. The return stroke travels at about 1 × 10⁸ m/s, close to one-third the speed of light.
About 95 percent of cloud-to-ground strikes are negative. The remaining 5 percent are positive cloud-to-ground bolts. Positive bolts often originate in the cirrus anvil, can reach peak currents above 100,000 amps, and travel many miles from the storm core.
A lightning flash typically extends 2 to 3 miles (3 to 5 km). The longest single flash certified by the World Meteorological Organization stretched 515 miles (829 km) across the southern United States on October 22, 2017 (certified in 2025 after detailed satellite reanalysis).
The longest-duration flash on record persisted for 17.1 seconds over northern Argentina and Uruguay on June 18, 2020.
Earth experiences about 44 flashes per second on average, with a seasonal range from roughly 35 in Northern Hemisphere winter to 55 in Northern Hemisphere summer.
Lake Maracaibo in Venezuela holds the highest flash density on Earth, about 250 flashes per square kilometer (per about 0.4 sq mi) per year, sustained by mountain-induced convergence and warm lake-surface evaporation.
Sprites, blue jets, and ELVES are transient luminous events triggered above thunderstorms by powerful lightning. Sprites flash red between altitudes of 31 and 56 miles (50 and 90 km). Blue jets reach about 31 miles (50 km). ELVES form expanding rings up to 250 miles (400 km) across at the base of the ionosphere.
Lightning excites global electromagnetic resonances in the cavity between Earth’s surface and the ionosphere. The fundamental Schumann resonance sits near 7.83 Hz, with overtones near 14.3, 20.8, 27.3, and 33.8 Hz.
Fulgurites are tubes of glassy, fused silica formed when a lightning current vaporizes air and partially melts sandy soil along the strike path. Specimens commonly run a few inches in diameter and can extend several feet underground along the strike path.
Volcanic plumes can generate their own lightning. Frictional charging between ash particles, plus ice formation high in the plume, produces what observers call “dirty thunderstorms.”
The National Weather Service records about 20 lightning fatalities per year in the United States, with hundreds of injuries. Roughly 9 of 10 strike victims survive, though long-term neurological and cardiac complications are common.
Roy Sullivan, a U.S. National Park Service ranger at Shenandoah National Park, was struck by lightning seven times between 1942 and 1977. Guinness World Records still lists him as the person struck the most times.
Common myths about lightning
Myth: Lightning never strikes the same place twice. Tall, conductive, well-grounded structures attract repeated strikes. The Empire State Building averages about 25 strikes per year, and lightning research towers at sites like the University of Florida’s International Center for Lightning Research and Testing log dozens of triggered and natural strikes each season.
Myth: You are only in danger if it is raining where you stand. Positive cloud-to-ground bolts can travel more than 10 miles (16 km) from the parent storm and strike under apparently clear sky. The National Weather Service refers to these as “bolts from the blue.” If you can hear thunder, you are within striking range.
Myth: Rubber soles or rubber tires insulate you. A discharge that has just punched through several miles of air will not be stopped by a few millimeters of rubber. A car offers protection because the metallic frame and body act as a Faraday-cage-like enclosure that diverts current around the occupant compartment.
Myth: Lightning rods attract lightning. A properly installed lightning protection system does not invite extra strikes. It provides a low-resistance path to ground for any strike that does occur, sparing the structure from being the conductor itself.
Myth: Crouching low protects you in an open field. The “lightning crouch” was retired from official NWS guidance years ago because field studies showed it offers little or no protection from a nearby strike. The current guidance is unambiguous: get to a substantial building or hard-topped vehicle.
Myth: Lightning is electricity from the storm cloud “draining” into the ground. A typical bolt releases intense electrical energy in a fraction of a second, but it does not equalize the cloud’s charge. The cloud regenerates the charge difference within seconds because the updraft and the noninductive charging process are still running.
Myth: A person struck by lightning carries a residual charge. Strike victims do not retain charge. Bystanders can and should provide first aid immediately. Cardiac arrest from lightning often responds well to prompt CPR.
Frequently asked questions
Why is the lightning channel hotter than the Sun’s surface? A huge electrical current dissipates inside a narrow air column over a few millionths of a second. That power density drives the channel briefly past the photospheric temperature of the Sun. Energy per unit time per unit volume, not total energy, is what produces the temperature.
What determines whether a flash is intracloud or cloud-to-ground? Geometry of the charge regions, the height of the cloud base above ground, and the conductivity of the path. Most flashes resolve internally because the negative middle layer and positive upper layer are closer to each other than the negative middle layer is to ground. Tall storms with bases far above the surface produce a higher fraction of intracloud flashes.
What is a positive cloud-to-ground flash, and why does it matter? A positive flash transfers positive charge from the upper, positively charged region of the cloud (often the cirrus anvil) to the ground. These flashes typically have larger peak currents, longer continuing currents, and a much higher chance of igniting wildfires. Positive flashes also account for many of the longer megaflashes captured by satellite mappers.
How is lightning measured from space? NOAA’s GOES-16 and GOES-17 satellites carry the Geostationary Lightning Mapper, an optical instrument that captures continuous video of lightning over the Western Hemisphere at 2-millisecond intervals. NASA earlier flew the Lightning Imaging Sensor on the Tropical Rainfall Measuring Mission satellite and on the International Space Station, building the global flash-rate climatology cited above.
What are sprites, blue jets, and ELVES? They are transient luminous events generated above large thunderstorms by intense cloud-to-ground discharges. Sprites are red flashes that span the mesosphere between 31 and 56 miles (50 and 90 km) of altitude. Blue jets shoot upward in a narrow cone from the cloud top to about 31 miles (50 km). ELVES are expanding rings of red emission up to 250 miles (400 km) wide that flash at the base of the ionosphere when an electromagnetic pulse from a strong return stroke reaches that height.
How dangerous is lightning, statistically? The National Weather Service estimates the annual probability of being struck in the United States at about 1 in 1.2 million, and the lifetime probability over 80 years at about 1 in 15,300. About 90 percent of victims survive, although recovery is often slow and incomplete. Following NWS guidance to seek substantial shelter when thunder is audible eliminates almost all of the residual risk.
What is the safest place during a thunderstorm? A fully enclosed building with electrical wiring and plumbing or a hard-topped vehicle. Avoid corded electronics, plumbing fixtures, and exterior windows during the storm. Wait until 30 minutes after the last audible thunder before returning outdoors.
Source notes
The physics in this article follows NOAA’s National Severe Storms Laboratory and the National Weather Service’s Understanding Lightning series. The flash distance and duration records come from World Meteorological Organization certifications, including the current 829 km (515 mi) distance record certified in 2025 from a 2017 megaflash, all based on Geostationary Lightning Mapper data from GOES-16 and GOES-17. The global flash rate of 44 ± 5 per second comes from analyses of NASA’s Optical Transient Detector and Lightning Imaging Sensor instruments. Catatumbo lightning data is drawn from NASA Earthdata’s coverage of the Lightning Imaging Sensor mission. The Roy Sullivan record is maintained by Guinness World Records using primary documentation from Shenandoah National Park. All source links sit in this article’s frontmatter.
Lightning is a high-current transient discharge that relieves the electric field built up in a thundercloud, between clouds, or between a cloud and the surface. The dominant generator is the noninductive charging of mixed-phase hydrometeors inside a deep cumulonimbus, which produces a quasi-tripole charge structure with a strong negative layer near the minus 15 °C isotherm and a positive shield above it. NASA’s Optical Transient Detector and Lightning Imaging Sensor missions place the global flash rate at 44 ± 5 per second, or about 1.4 billion flashes per year, with the great majority of flashes confined within or between clouds.
Why lightning still surprises specialists
The microphysics of charge separation, the propagation of leaders through nominally insulating air, and the coupling between tropospheric discharges and the mesosphere are all still under active investigation. Laboratory experiments going back to Reynolds, Brook, and Gourley in the 1950s and refined by Takahashi and by Saunders and colleagues in the 1990s established that ice crystals colliding with riming graupel exchange charge, with the sign of transfer dependent on temperature, liquid water content, and impact velocity. Above a critical reversal temperature near minus 15 °C, ice crystals charge positive and graupel charges negative; below that temperature the polarity reverses. This sensitivity explains why storms with deep mixed-phase regions and strong updrafts produce far more lightning per unit precipitation than warm, marine convection.
Leader propagation through air is itself an unsolved problem. Atmospheric breakdown fields measured in laboratory air sit near 3 megavolts per meter at sea level pressure, but balloon and rocket soundings inside thunderclouds rarely record more than about 400 kilovolts per meter, an order of magnitude below the conventional breakdown threshold. The runaway-breakdown hypothesis proposed by Gurevich and colleagues, in which relativistic electrons seeded by cosmic rays multiply through avalanche, has gained support from observations of terrestrial gamma-ray flashes and X-ray emission from leader tips. Whether runaway breakdown initiates leaders, sustains their propagation, or only accompanies them remains contested.
Megaflash detection has likewise reset prior assumptions. Before the Geostationary Lightning Mapper instruments on GOES-16 and GOES-17 began continuous optical mapping in 2017, the longest documented flashes spanned a few hundred kilometers. The current WMO distance record, certified in 2025, is 829 km (515 mi) for a single flash recorded on October 22, 2017 across the southern United States; the duration record, certified in 2022, is 17.1 seconds for a flash on June 18, 2020 over Argentina and Uruguay. Both extremes were extracted from the trailing stratiform regions of mesoscale convective systems where horizontal positive charge layers extend across hundreds of kilometers. The implication is that megaflashes are not curiosities but a regular feature of large MCSs, with implications for aviation, wildfire ignition, and the design of ground-based detection networks.
Key facts about lightning
Channel temperature in the return stroke peaks near 50,000 °F (28,000 °C), or roughly 30,000 K. Plasma physics models put the channel core electron density above 10¹⁷ per cubic centimeter and the channel diameter at about 0.4 to 1 inch (1 to 3 cm) during peak current.
Typical first-return-stroke peak currents lie between 20,000 and 40,000 amps. Median values fall near 30,000 amps for negative cloud-to-ground flashes and run higher for positive flashes, with the strongest documented strokes exceeding 200,000 amps.
Channel resistance during the return stroke drops to roughly 0.05 ohms per meter, allowing the leader-deposited charge to flow back to ground in tens of microseconds.
Stepped-leader average propagation speed sits near 1 × 10⁵ m/s, with step lengths of 30 to 90 m and inter-step intervals near 50 microseconds. Return-stroke front speeds reach 1 × 10⁸ to 2 × 10⁸ m/s, between one-third and two-thirds the speed of light.
A typical cloud-to-ground discharge involves a potential difference of 100 megavolts to 1 gigavolt and transfers about 5 to 25 coulombs of charge.
Negative cloud-to-ground flashes account for roughly 95 percent of strikes that reach the surface in the contiguous United States. Positive cloud-to-ground flashes (about 5 percent) frequently originate in the upper anvil, exhibit larger peak currents, longer continuing currents, and disproportionately ignite wildfires.
The National Lightning Detection Network, with continental coverage since 1989 and progressively upgraded through the 1990s, has reported on the order of 20 to 25 million cloud-to-ground flashes per year over the United States in recent decades. Intracloud flashes outnumber cloud-to-ground flashes by a factor of 5 to 10.
The current WMO megaflash records are 515 mi (829 km) horizontal extent (October 22, 2017, southern United States, certified in 2025) and 17.102 ± 0.002 seconds duration (June 18, 2020, Argentina-Uruguay, certified in 2022).
Catatumbo lightning over Lake Maracaibo records the highest annual flash density measured by satellite, about 250 flashes per square kilometer (per about 0.4 sq mi), driven by orographically forced convergence and persistent low-level moisture from the lake.
Transient luminous events form a family of mesospheric and stratospheric discharges. Sprites span 31 to 56 mi (50 to 90 km) altitude, are red from N₂ first positive emission, and are triggered preferentially by large positive cloud-to-ground flashes with high charge moment change. Halos appear as broad disks just above sprite onset. Blue jets shoot upward from cloud tops to about 31 mi (50 km), gigantic jets bridge thunderstorm tops to the lower ionosphere at roughly 56 mi (90 km), and ELVES form 200- to 250-mi-wide (320 to 400 km) rings at the base of the ionosphere from the electromagnetic pulse of the return stroke.
Lightning supplies most of the energy that excites the Schumann resonances in the cavity between Earth’s surface and the lower ionosphere. The fundamental mode sits near 7.83 Hz, with overtones at 14.3, 20.8, 27.3, and 33.8 Hz. The fundamental wavelength matches Earth’s circumference.
Fulgurites are tube-shaped structures of fused, vitrified silica, dominantly the amorphous mineraloid lechatelierite, formed when the lightning channel deposits enough energy to melt sandy soil along the strike path. Sand fulgurites typically run 1 to 2 inches (2.5 to 5 cm) in diameter and can extend several feet underground.
Volcanic plumes generate lightning through fractoemission near the vent, triboelectric charging of ash particles in the rising column, and ice-based noninductive charging where the plume penetrates the freezing level. Eyjafjallajökull (Iceland, 2010) and Hunga Tonga (2022) produced spectacular plume lightning displays. Hunga Tonga generated about 400,000 flashes in roughly six hours during its January 2022 eruption.
The National Weather Service records about 20 lightning fatalities and several hundred injuries per year in the United States. Roy Sullivan, a National Park Service ranger at Shenandoah National Park, was struck by lightning seven times between 1942 and 1977 and is recognized by Guinness World Records as the person struck the greatest number of times.
Georg Wilhelm Richmann, replicating Franklin’s lightning experiments in Saint Petersburg on August 6, 1753, was killed when a discharge, possibly ball lightning, struck his apparatus. He is generally regarded as the first person known to have died while conducting an electrical experiment.
Common myths about lightning
Myth: Lightning will not strike the same place twice. Tall, well-grounded structures attract repeated strikes by orders of magnitude relative to flat ground. The Empire State Building averages about 25 strikes per year. Lightning research towers at Camp Blanding, Florida, and at Saint-Privat-d’Allier, France, log dozens of natural and rocket-triggered strikes each season.
Myth: A flash and an immediate thunderclap mean the strike was overhead, but a delayed thunderclap means it was safely far away. Bolts from the blue from the upper anvil routinely travel 10 to 25 mi (16 to 40 km) horizontally before going to ground. Audible thunder, which propagates only about 10 mi (16 km) before atmospheric attenuation makes it inaudible, is itself a sign you are within strike range.
Myth: Lightning rods attract more strikes to a building. A properly designed Lightning Protection Institute or NFPA 780 system provides a low-impedance path to ground that intercepts strikes that would have hit the structure anyway, terminating the leader at the air terminal and routing the return-stroke current safely to a grounding electrode. The system does not measurably increase strike incidence on the structure.
Myth: The “lightning crouch” gives meaningful protection in the open. Field studies and statistical analyses by Holle and others led the National Weather Service to retire the crouch from official guidance more than two decades ago. Substantial buildings or hard-topped vehicles are the only reliably safe locations during a thunderstorm.
Myth: Cars protect occupants because of their rubber tires. The protection is provided by the metallic body and frame, which acts approximately as a Faraday cage, redirecting current along the exterior. Tires play no significant role; convertibles and open-cabin vehicles do not provide equivalent protection.
Myth: Ball lightning is folklore. Witness reports across centuries are consistent enough that the phenomenon is generally accepted as real. The mechanism is contested. Candidate models include silica nanoparticle combustion (Abrahamson and Dinniss, 2000), microwave excitation of plasma cavities, and persistent vortex structures of charged plasma. None has gained universal acceptance, in part because reproducible laboratory analogs remain rare.
Myth: A lightning victim retains charge and is dangerous to touch. Strike victims do not store charge. Cardiac arrest from lightning frequently responds to immediate CPR, so first-responder hesitation costs lives without medical justification.
Frequently asked questions
Why does the lightning channel briefly exceed the temperature of the photosphere? Power density rather than total energy drives the channel temperature. A return stroke sends a huge current through a channel roughly 0.4 to 1 in (1 to 3 cm) wide for tens of microseconds. The resulting volumetric heating rate is many orders of magnitude above stellar surface conditions. The channel cools rapidly, dropping to a few thousand kelvin within milliseconds.
What sets the polarity of cloud-to-ground discharges? The vertical position and magnitude of the dominant charge regions. In the canonical tripole structure, leaders preferentially emerge from the largest concentration of charge that can find a propagation path to ground. Negative cloud-to-ground flashes draw from the central negative layer near minus 15 °C. Positive cloud-to-ground flashes draw from the upper positive shield, often via the cirrus anvil, and are favored when the lower charge regions are weakened (decaying storms, sheared anvils, severe storms with tilted updrafts).
How do megaflashes propagate hundreds of miles without losing connection to the parent storm? Mesoscale convective systems develop extensive trailing stratiform regions with quasi-horizontal positive charge layers tens of kilometers thick and hundreds of kilometers long. Bidirectional leaders inside this layer can extend through the layer at velocities of about 30,000 to 60,000 m/s, sustained by continuing currents. Geostationary Lightning Mapper data on GOES-16 and GOES-17 first revealed the full extent of these flashes; ground-based networks had previously seen them only in fragments.
What is a terrestrial gamma-ray flash, and how does it relate to lightning? TGFs are submillisecond bursts of MeV-scale gamma rays detected from low-Earth orbit and originating in or near thunderstorm tops. They are produced by relativistic runaway electron avalanches accelerated in the strong electric fields ahead of leader tips. TGF observations from RHESSI, Fermi GBM, AGILE, and ASIM provide the strongest evidence that runaway breakdown is operating inside or alongside conventional lightning.
What is the relationship between lightning and the global atmospheric electric circuit? Thunderstorms act as battery cells driving current upward into the ionosphere. The fair-weather return current flows downward globally at about 1 to 2 picoamps per square meter, maintaining the roughly 250-kilovolt potential difference between the surface and the lower ionosphere. About 1,000 to 2,000 thunderstorms run continuously on Earth, producing the 44 flashes per second that sustain this circuit. The Carnegie curve, named for measurements by the research vessel Carnegie in the 1920s, shows the diurnal variation in the fair-weather field tracking global thunderstorm activity in tropical land regions.
What instrumentation defines the modern observational record? Ground networks include the U.S. National Lightning Detection Network, the European Cooperation for Lightning Detection (EUCLID), and the Earth Networks Total Lightning Network, which use time-of-arrival and magnetic-direction-finding methods to locate strikes within hundreds of meters. Optical detection from space comes from the Geostationary Lightning Mappers on GOES-16 and GOES-17, the Lightning Imager on Meteosat Third Generation, NASA’s Lightning Imaging Sensor, and the earlier Optical Transient Detector. Combined ground and space data feed regional and global flash climatologies.
How does climate change affect lightning frequency? Convective available potential energy and the depth of the mixed-phase region both respond to warming. Studies by Romps and others (Science, 2014) suggested a roughly 12 percent increase in U.S. cloud-to-ground flash rate per degree Celsius of surface warming, though later work using different convection metrics has produced lower estimates. Regional changes depend on circulation patterns, aerosol loading (which modulates cloud microphysics and ice-phase production), and land-use change. The signal is unambiguous in some regions and contested in others.
Source notes
The microphysics of noninductive charging is summarized from peer-reviewed work in the Journal of the Atmospheric Sciences and from NOAA’s National Severe Storms Laboratory. Megaflash records and their statistical context come from World Meteorological Organization certifications and the accompanying Bulletin of the American Meteorological Society articles on the 2022 and 2025 certified records. Leader-stroke physics, transient luminous event taxonomy, and global-circuit coupling follow standard references including Rakov and Uman’s Lightning: Physics and Effects (Cambridge University Press) and the National Weather Service’s Understanding Lightning series. Schumann resonance values come from peer-reviewed measurements summarized in the Wikipedia entry whose cited references have been verified. The full source list sits in this article’s frontmatter.
