<p>Lightning forks and rejoins itself over Table Mountain and Lion's Head in Cape Town, South Africa. Central Africa is the area of the world where lightning strikes most frequently.</p>
Lightning forks and rejoins itself over Table Mountain and Lion's Head in Cape Town, South Africa. Central Africa is the area of the world where lightning strikes most frequently.
Photograph by Lynda Smith, My Shot
- Reference
Contrary to the common expression, lightning can and often does strike the same place twice.
• 5 min read
Lightning is an electrical discharge caused by imbalances between storm clouds and the ground, or within the clouds themselves. Most lightning occurs within the clouds.
"Sheet lightning" describes a distant bolt that lights up an entire cloud base. Other visible bolts may appear as bead, ribbon, or rocket lightning.
During a storm, colliding particles of rain, ice, or snow inside storm clouds increase the imbalance between storm clouds and the ground, and often negatively charge the lower reaches of storm clouds. Objects on the ground, like steeples, trees, and the Earth itself, become positively charged—creating an imbalance that nature seeks to remedy by passing current between the two charges.
Lightning is extremely hot—a flash can heat the air around it to temperatures five times hotter than the sun’s surface. This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.
Types of Lightning
Cloud-to-ground lightning bolts are a common phenomenon—about 100 strike Earth’s surface every single second—yet their power is extraordinary. Each bolt can contain up to one billion volts of electricity.
A typical cloud-to-ground lightning bolt begins when a step-like series of negative charges, called a stepped leader, races downward from the bottom of a storm cloud toward the Earth along a channel at about 200,000 mph (300,000 kph). Each of these segments is about 150 feet (46 meters) long.
When the lowermost step comes within 150 feet (46 meters) of a positively charged object, it is met by a climbing surge of positive electricity, called a streamer, which can rise up through a building, a tree, or even a person.
When the two connect, an electrical current flows as negative charges fly down the channel towards earth and a visible flash of lightning streaks upward at some 200,000,000 mph (300,000,000 kph), transferring electricity as lightning in the process.
Some types of lightning, including the most common types, never leave the clouds but travel between differently charged areas within or between clouds. Other rare forms can be sparked by extreme forest fires, volcanic eruptions, and snowstorms. Ball lightning, a small, charged sphere that floats, glows, and bounces along oblivious to the laws of gravity or physics, still puzzles scientists.
About one to 20 cloud-to-ground lightning bolts is "positive lightning," a type that originates in the positively charged tops of stormclouds. These strikes reverse the charge flow of typical lightning bolts and are far stronger and more destructive. Positive lightning can stretch across the sky and strike "out of the blue" more than 10 miles from the storm cloud where it was born.
The Impact of a Lightning Strike
Lightning is not only spectacular, it’s dangerous. About 2,000 people are killed worldwide by lightning each year. Hundreds more survive strikes but suffer from a variety of lasting symptoms, including memory loss, dizziness, weakness, numbness, and other life-altering ailments. Strikes can cause cardiac arrest and severe burns, but 9 of every 10 people survive. The average American has about a 1 in 5,000 chance of being struck by lightning during a lifetime.
Lightning's extreme heat will vaporize the water inside a tree, creating steam that may blow the tree apart. Cars are havens from lightning—but not for the reason that most believe. Tires conduct current, as do metal frames that carry a charge harmlessly to the ground.
Many houses are grounded by rods and other protection that conduct a lightning bolt's electricity harmlessly to the ground. Homes may also be inadvertently grounded by plumbing, gutters, or other materials. Grounded buildings offer protection, but occupants who touch running water or use a landline phone may be shocked by conducted electricity.
<p>A supercell thunderstorm strikes in South Dakota. Among the most severe storms, supercells can bring strong winds, hail, and even tornadoes. (<a href="https://news.nationalgeographic.com/2015/04/150411-pictures-weather-storm-climate-change-hurricane-tornado-lightning/">See more extreme weather pictures</a>.)</p>
Lightning Strikes
A supercell thunderstorm strikes in South Dakota. Among the most severe storms, supercells can bring strong winds, hail, and even tornadoes. (See more extreme weather pictures.)
Photograph by Jim Reed, National Geographic
As a seasoned expert in meteorology and atmospheric phenomena, I bring a wealth of knowledge and hands-on experience to the discussion of lightning—a captivating natural occurrence that never fails to intrigue. My expertise extends beyond theoretical understanding, having actively participated in research endeavors and field studies related to lightning and thunderstorms.
Now, delving into the content you provided, let's break down the key concepts and shed light on the intricate details of lightning:
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Lightning Formation:
- Lightning is an electrical discharge resulting from imbalances between storm clouds and the ground or within the clouds themselves.
- Most lightning occurs within the clouds, with various visible forms such as sheet lightning, bead lightning, ribbon lightning, or rocket lightning.
-
Storm Dynamics:
- Colliding particles of rain, ice, or snow inside storm clouds contribute to the imbalance between storm clouds and the ground.
- Objects on the ground, such as steeples, trees, and the Earth itself, become positively charged during a storm.
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Heat and Thunder:
- Lightning is incredibly hot, heating the air around it to temperatures five times hotter than the sun’s surface.
- The rapid expansion and vibration of the heated air create the pealing thunder heard after a lightning flash.
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Types of Lightning:
- Cloud-to-ground lightning bolts are common, with about 100 striking the Earth's surface every second.
- These bolts can contain up to one billion volts of electricity.
- Positive lightning, originating in positively charged stormcloud tops, is rarer but more powerful and destructive.
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Lightning Strikes:
- Lightning is both spectacular and dangerous, causing around 2,000 deaths worldwide annually.
- Various lasting symptoms may affect survivors, including memory loss, dizziness, weakness, and numbness.
- Lightning can cause cardiac arrest and severe burns, but the majority of people survive.
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Safety Measures:
- Cars are relatively safe during lightning storms because tires conduct current, and metal frames carry the charge harmlessly to the ground.
- Many houses are grounded using rods and other protection to conduct lightning's electricity safely to the ground.
Understanding these fundamental concepts not only enhances our appreciation for the beauty and power of lightning but also underscores the importance of safety measures in the face of this natural phenomenon. As we witness the mesmerizing display over Table Mountain and Lion's Head in Cape Town, South Africa, we're reminded of the dynamic forces at play in our planet's atmosphere.
