Why Lightning Can Strike Upward From the Ground
A thunderstorm may appear to send every lightning bolt downward, but the electrical activity near the ground is far more dynamic than it looks. Under the right conditions, a tall tower, skyscraper, wind turbine, mountaintop structure, or communications mast can launch an electrically charged channel toward the cloud. This phenomenon is known as upward lightning, and it reveals that a lightning flash is not simply an object falling from the sky. It is a rapidly developing electrical connection shaped by charge, air, terrain, weather, and the structures rising from Earth’s surface.
Yes, lightning can begin at the ground and travel upward. True upward lightning usually starts from a tall or elevated object whose tip intensifies the surrounding electric field. A leader then develops from the structure and propagates toward an electrically charged region of the storm.
Towers, wind turbines, skyscrapers, antennas, and elevated structures are the most likely starting points.
An upward flash may be triggered by nearby lightning or, less commonly, begin without an immediately preceding flash.
An upward-moving return stroke in ordinary lightning is not the same as a flash whose first leader originates from a structure.
How a Thunderstorm Becomes Electrified
Lightning begins with charge separation inside a cloud. In a developing thunderstorm, powerful updrafts carry water droplets and small ice crystals upward into regions where temperatures are below freezing. The cloud may contain supercooled liquid droplets, lightweight ice crystals, and larger pellets of rimed ice known as graupel.
When these particles collide, electrical charge can be transferred between them. The exact microscopic details are still an active area of research, but scientists know that the different particles tend to acquire different charges. Their unequal sizes and fall speeds then help separate those charges into distinct regions within the storm.
A simplified thunderstorm often has a major region of negative charge in its middle-to-lower portion and a positive region higher in the cloud, although actual storms may contain several layers and pockets of charge. The storm’s electric field also rearranges charge on the ground and on objects beneath it.
Air normally acts as an electrical insulator. As the electric field strengthens, however, portions of the air become ionized. Electrons and charged particles create narrow, increasingly conductive pathways through which a much larger electrical discharge can develop.
Does Ordinary Lightning Already Move Upward?
This question has two scientifically different answers. In a typical negative cloud-to-ground flash, the initial channel develops downward from the cloud. A faint, branching channel called a stepped leader advances toward Earth in a series of short movements.
As that leader approaches, the electric field near trees, buildings, poles, and other elevated objects becomes intense. One or more upward connecting leaders may rise from the surface. When a downward leader and an upward leader connect, they establish a conductive path between the cloud and the ground.
A powerful current then surges through the completed channel. The brilliant return stroke generally travels upward from the connection point toward the cloud. This is the part of the flash that is easiest for people to see.
The upward return stroke in an ordinary cloud-to-ground flash does not mean the entire event began on the ground. In true upward lightning, the initiating leader itself emerges from a tall grounded object and extends toward the storm.
Ordinary downward flash
The flash is initiated within the cloud. A leader develops downward, an upward leader rises to meet it, and the bright return stroke travels through the connected path.
True upward flash
The initial leader begins at the top of a tall or elevated structure and propagates upward before a conventional downward leader reaches that object.
How True Upward Lightning Develops
A tall structure changes the local electrical environment. Charge becomes concentrated near narrow, pointed, or sharply curved parts of the structure. This concentration strengthens the electric field immediately around the tip.
If the field becomes sufficiently strong, the surrounding air can begin to ionize. Small streamer discharges may appear, and one of them may develop into a leader capable of sustaining more current and advancing farther into the atmosphere.
The charged cloud creates a substantial electrical potential between different parts of the atmosphere and the ground.
The top of a tower, turbine, mast, or elevated building concentrates the field more strongly than the surrounding flat surface.
The air near the structure becomes partially ionized, creating faint channels of charged particles.
A more conductive channel develops from the structure and propagates upward, sometimes branching as it grows.
The developing channel can connect with charged regions or other channels, allowing current to flow through the structure.
The process happens extremely quickly and is difficult to study with ordinary cameras. Researchers use high-speed imaging, electric-field instruments, current sensors, and lightning-location networks to reconstruct how the leaders form and connect.
Triggered and Self-Initiated Upward Lightning
Scientists commonly separate upward lightning into two broad categories based on how the upward leader begins.
Lightning-triggered upward flashes
Many upward flashes occur shortly after another lightning discharge in the surrounding storm. That earlier flash rapidly changes the local electric field. The change can make conditions favorable for one or several tall structures to launch upward leaders.
In some observations, multiple towers have produced upward leaders almost simultaneously after a nearby flash. This demonstrates that the triggering event can alter the electrical environment across a broad area rather than affecting only one structure.
Self-initiated upward flashes
An upward leader can also begin without an immediately preceding lightning flash that clearly triggered it. These events are often called self-initiated upward lightning.
They have been observed under particular meteorological conditions, including some winter thunderstorms and strongly electrified storms with low cloud charge regions, vigorous winds, or precipitation near elevated structures. Scientists continue to investigate the exact combination of electric-field, cloud, terrain, and weather conditions that allows these events to begin.
Lightning is not a solid object moving in only one direction. It is an electrical discharge that develops through branching ionized channels. Different portions of the same event can propagate upward, downward, or sideways.
Why Tall Structures Are Especially Important
Height reduces the distance between a structure and the charged portions of a storm, but height alone does not explain everything. The structure’s shape, location, elevation, electrical connection to the ground, and surrounding terrain can all influence the strength of the electric field near its top.
A tower on a mountain may behave as though it were much taller than the same tower placed on level ground. Sharp antennas, turbine blades, lightning rods, and other narrow components can also produce intense local fields.
Tall objects do not simply “pull” every bolt toward them from unlimited distances. Instead, they alter the local conditions in which streamers, leaders, and attachment processes develop. A shorter object may still be struck, while a taller object nearby may not be. Lightning behavior is probabilistic, not perfectly predictable.
| Structure or location | Why it is relevant | Potential concern |
|---|---|---|
| Communications towers | They are tall, conductive, and often placed on elevated terrain. | Damage to antennas, transmitters, power systems, and connected electronics. |
| Wind turbines | Modern turbines have very high towers and rotating blade tips that reach even greater elevations. | Blade damage, electrical faults, downtime, and maintenance costs. |
| Skyscrapers | Upper sections extend into stronger electric fields and may be struck repeatedly. | Surges, fires, exterior damage, and disruptions to building systems. |
| Mountain installations | Topography increases effective elevation and reduces the distance to charged cloud regions. | Frequent exposure and difficult inspection or repair conditions. |
| Aircraft | An aircraft passing through a strong electric field may help initiate a discharge. | Temporary system effects, surface damage, and required post-flight inspection. |
Why Upward Lightning Matters to Engineers
Upward lightning is more than a visually unusual event. It can expose tall structures to electrical currents that differ in duration, repetition, and development from conventional downward strikes.
Engineers use lightning-protection systems to intercept current and guide it through controlled conductive paths toward the ground. Protection may include air terminals, bonding, grounding networks, surge-protection devices, shielding, and specially designed conductive components.
Wind turbines present a distinctive challenge. The blades are long, frequently made from composite materials, and repeatedly pass through the highest part of the structure’s electrical field. A turbine may therefore experience both conventional downward strikes and upward discharges originating near a blade tip.
Understanding these events helps designers improve blade receptors, internal conductors, grounding systems, inspection schedules, and lightning-detection methods. Similar research supports the protection of broadcasting towers, observation platforms, high-rise buildings, launch facilities, and mountain weather stations.
St. Elmo’s Fire: Related, but Not Lightning
A blue, violet, or whitish glow may sometimes appear around the tip of a ship’s mast, aircraft wing, antenna, steeple, or another pointed object during strongly electrified weather. This phenomenon is known as St. Elmo’s fire.
St. Elmo’s fire is a relatively continuous corona discharge produced when a strong electric field ionizes the air near an elevated or sharply pointed object. It is not a complete lightning channel, although it arises from related electrical conditions.
Corona discharges and streamers can be early signs that the local electric field is intense. They should never be treated as harmless entertainment or as an invitation to remain outside and record the storm.
Never stand near a tower, isolated tree, wind turbine, fence, rooftop, mast, or other elevated object to watch electrical activity. If thunder is audible, move promptly into a substantial enclosed building or a fully enclosed metal-topped vehicle.
Common Questions About Upward Lightning
Can an ordinary tree produce upward lightning?
A tree can launch an upward connecting leader when a downward lightning leader approaches. However, independently initiated upward flashes are more strongly associated with very tall structures or objects on elevated terrain. A tall tree can still be dangerous and should never be used as shelter.
Does lightning always strike the tallest object?
No. Taller objects are often more likely to produce upward leaders, but lightning does not follow a simple tallest-object rule. Distance, terrain, object shape, charge distribution, and the branching path of the leader all matter.
Can upward lightning occur during snowstorms?
Yes. Upward flashes have been documented during electrified winter storms and thundersnow. Some winter environments can bring strong cloud charge regions close to towers or mountain structures, creating favorable conditions for upward initiation.
Is ground-to-cloud lightning artificial?
Not necessarily. Rockets and other technologies can deliberately trigger lightning for research, but naturally occurring upward flashes also begin from existing towers, turbines, skyscrapers, and elevated structures.
Can upward lightning damage a structure?
Yes. Current may enter conductive components, wiring, control systems, antennas, turbine blades, or grounding networks. Proper protection cannot prevent every strike, but it can greatly reduce the risk of severe damage and fire.
Is St. Elmo’s fire the same as an upward leader?
No. St. Elmo’s fire is a corona discharge that may persist as a glow. An upward leader is a more developed, propagating electrical channel that may become part of a lightning flash.
How to Stay Safe During Any Thunderstorm
The physics of upward lightning reinforces a basic safety lesson: being close to the tallest object in an exposed area is dangerous. A person standing on a rooftop, ridge, field, beach, boat, or open hill may become one of the most elevated objects nearby.
- Enter a substantial enclosed building or a fully enclosed metal-topped vehicle when thunder is heard.
- Do not shelter beneath an isolated tree, tower, open pavilion, rocky overhang, or small shed.
- Move away from hilltops, ridges, beaches, open fields, bodies of water, fences, utility lines, and wind turbines.
- Never lie flat on the ground because this increases exposure to current spreading through the surface.
- Indoors, avoid corded electrical equipment, plumbing, windows, doors, porches, and direct contact with concrete walls or floors.
- Continue following local weather alerts and wait until the danger has clearly passed before returning outdoors.
Lightning Is a Connection, Not a One-Way Bolt
Upward lightning changes the familiar picture of electricity simply dropping out of a cloud. A thunderstorm creates an evolving electric field, while the landscape and built environment influence where conductive channels can form.
In ordinary cloud-to-ground lightning, downward and upward leaders cooperate to complete the path. In a true upward flash, the first sustained leader originates from a tall grounded structure and advances toward the storm. Nearby lightning may trigger that leader, or unusual atmospheric conditions may allow it to begin independently.
Studying these events helps scientists understand atmospheric electricity and gives engineers practical knowledge for protecting turbines, towers, aircraft, communication systems, and high-rise buildings. It also delivers a simple reminder for everyone watching a storm: the ground beneath a thundercloud is not electrically passive, and the safest view is always from secure shelter.
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Take the Bing Homepage QuizSources and Further Reading
- NOAA National Severe Storms Laboratory, Severe Weather 101: Lightning Types .
- NOAA National Severe Storms Laboratory, Frequently Asked Questions About Lightning .
- National Weather Service, Lightning Safety Tips and Risk-Reduction Guidance .
- American Geophysical Union, High-Speed Observations of the Lightning Attachment Process .
- Royal Meteorological Society, What Is Upward Lightning? .
- World Meteorological Organization International Cloud Atlas, Saint Elmo’s Fire .
This educational article distinguishes true upward lightning initiation from the upward return stroke present in many ordinary cloud-to-ground flashes. Lightning processes remain an active field of atmospheric research, and some initiation mechanisms are not yet completely understood.