Does Lightning Really Strike Up? The Science Behind Upward Lightning

Lightning doesn’t always follow the path we expect. Most people picture lightning bolts striking down from the clouds to the earth. But lightning can shoot up from the Earth’s surface under certain conditions. This ground-to-cloud lightning happens mostly around tall structures like skyscrapers and towers. Traditional cloud-to-ground lightning occurs more often, but upward lightning isn’t rare.

What is lightning?

Thunderclouds create lightning by separating charges. The top of the cloud collects positive charges, while negative charges gather at the bottom. Lightning happens when the difference in electrical charges becomes so great that it breaks down the air’s insulating ability.

Traditional cloud-to-ground lightning starts when a channel of negative charge moves toward the ground. This channel is called a stepped leader and is invisible to the naked eye. We don’t see this part. It zigzags down to the ground in about 50-yard jumps. And, it happens incredibly fast. As this charged channel gets close to the ground, trees and buildings send up positive charges (streamers) to meet it. When the opposite charges connect, a powerful electrical current surges back up the path. This creates the bright flash we call lightning.

What is upward lightning?

Can lightning strike from the ground up? Upward lightning can actually happen several ways. When regular lightning forms, the invisible energy bolt shoots downward from the sky to the ground. This creates the classic lightning bolt from the heavens. However, it’s not quite as it seems. The bright flash we actually see and call lightning is that energy bolt racing back up to the clouds after it touches the ground. It is like a reverberation, except with powerful energy fields instead of sound. So, even with regular lightning, there is a type of upward lightning action happening.

In true upward lightning, though, the whole process really does start from the ground, or really, from something attached to the Earth’s surface. Unlike standard lightning, which begins in storm clouds, ground-to-cloud lightning begins with a tall object. The lightning forms from these structures and travels upward. This happens most often with towers, skyscrapers, and mountaintops.

Spotting upward lightning in photos is easy once you know what to look for – they have distinctive branching patterns that spread upward instead of downward.

Upward lightning (also called ground-to-cloud lightning) completely reverses this process. It starts when a tall object creates its own lightning leader that travels upward toward the storm cloud. The tall structures change how lightning behaves. Objects at higher elevations have a stronger electric field at their tips. And, these taller structures with stronger electric fields are ideal for upward lightning leaders to start.

Studies show that structures taller than about 328 feet (100 meters) tend to start upward lightning strikes more often. Regular lightning spreads its energy across multiple points. In contrast, upward lightning focuses its power at the top of these tall structures.

How does upward lightning work?

For upward lightning to happen, there needs to be storm electrification and a charged cloud region. The tall object (like the top of a skyscraper) creates a super-strong electric field at its tip. This concentrated field can either start an upward leader by itself or respond to electric field changes from nearby lightning.

Winter storms with heavy snow create the perfect conditions for self-initiated upward lightning. The low cloud bases bring tall objects right into or near the charged regions within the clouds.

Types of upward lightning strikes

Scientists group upward lightning into several distinct types.

Ground-to-cloud lightning

Ground-to-cloud lightning is the basic form of upward lightning. Cloud-to-ground and ground-to-cloud lightning are actually just the same thing seen from different angles. The bright flash you see travels upward from the ground.

The whole process starts when clouds send negatively charged electricity toward the ground through an invisible channel. When these particles touch down, they meet positively charged objects on the ground. This causes positive energy to race back up the channel that’s already been created – and that’s the visible lightning streak we all recognize.

Triggered upward lightning

Lightning-Triggered Upward Lightning (LTUL) happens in response to nearby lightning activity. Horizontally spreading positive ground flashes often trigger LTUL. These events love to happen during big storm systems with large areas of steady precipitation. When conditions are just right, these upward flashes can happen in rapid-fire succession. Researchers once counted 52 upward flashes from Toronto’s CN Tower in just 84 minutes.

Self initiated upward lightning

Self-Initiated Upward Lightning (SIUL) develops without any previous lightning activity. This phenomenon usually occurs in winter, especially during heavy snow events like blizzards. During snow storms, the clouds are lower in the sky than normal. This means the clouds are more likely to sweep or hover over tall buildings. The buildings or tall objects are now right in the charged regions of the cloud, which might then trigger upward lightning. Also, the tops of the buildings being might come in contact with electrically charged snowfall, which can also trigger lightning.

These lightning flashes can last up to two seconds, with leaders traveling impressive horizontal distances. After studying one major blizzard, scientists found that a significant 70-90% of all lightning in snow-covered areas was self-initiated upward lightning. The lightning jumps from tall objects to the sky in record numbers during winter.

Where and when does upward lightning occur

Lightning has favorite places! The geography and timing reveal some interesting patterns across our planet. Upward lightning doesn’t happen just anywhere or anytime – it picks very specific spots under particular weather conditions.

Upward lightning almost exclusively starts from tall structures – towers, skyscrapers, or mountaintops. The taller the building, the more lightning strikes it gets. Structures rising above 1,000 feet might receive multiple strikes during a single thunderstorm.

The Säntis Tower in Switzerland is a prime example. This 124-inch-tall structure sits atop the Appenzell Alps and gets zapped by lightning more than 100 times every year.

Natural upward lightning (without tall human-made structures) is incredibly rare. It occurs mainly at unique high-elevation spots. Some examples include Pilot Peak near Yellowstone National Park, Castle Rock in Utah, and the famous Matterhorn in Switzerland. When cities have multiple tall buildings close together, upward lightning sometimes shoots up from several at once. This spectacular light show regularly happens in Chicago. Lightning leaps simultaneously from the Sears Tower, John Hancock Building, and Trump Tower.

Upward Lightning Facts

• Between 2000 and 2015 (plus mid-2020 through 2023), researchers counted 956 upward lightning flashes at Austria’s Gaisberg Tower.
• One “perfect storm” in Toronto, Canada, was really remarkable. Scientists watched 52 upward flashes shot from the CN Tower in just 84 minutes during this extraordinary weather event. That is almost one lightning bolt per minute streaming upward from a single tower!

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