A lightning bolt is a flash of light produced when a cloud-to-ground lightning strike occurs. It can be incredibly wide, spanning as much as 40 meters—that’s almost 130 feet! However, lightning bolts don’t stay static for long. After just one millisecond, the bolts have already shrunk to about 10 meters in width.
Since we see lightning so fleetingly, it can be challenging to measure its exact dimensions at any point in time. In fact, the most recent research suggests that a lightning bolt could even be considered an expanding sphere of superheated plasma with a radius of just 2 meters from tip to tail. When you break it down like this, it becomes clearer why scientists have such difficulty measuring this natural phenomenon accurately.
Lightning Facts: Know the Basics
Before moving on to the finer details, here are a few basic facts related to lightning that you should know:
- Lightning is not one flash, but rather a series of successive moments along a path called a “lightning channel.”
- The channel can extend up to 100 kilometers, or 60 miles, and is formed of charged particles that interact with each other during the flow of current.
- Lightning can reach temperatures as high as 30,000 degrees Fahrenheit, which is hotter than the surface of the sun.
- Lightning can strike up to 10 miles from the area where cloud-to-ground lightning occurs.
Factors That Affect the Width of a Lightning Bolt
The width of a lightning bolt is a pretty important measurement, as it can tell us quite a lot about the conditions inside the bolt itself. The primary factors that will determine the width of a lightning bolt are the following:
The charge of the storm cloud, a higher charge within the cloud will lead to a wider lightning bolt. The distance between the charged cloud and the ground will also impact the width of the lightning bolt.
The type of soil beneath the charged cloud, sandy soil will cause a wider lightning bolt than clay soil. The strength of the upward air current, strong upward air current will result in a wide lightning bolt.
How strong the downward air current is flowing towards the ground, the stronger the downward air current is flowing, the narrower the lightning bolt will be. The type of cloud, different types of clouds produce different widths of lightning bolts.
What Is the Width of a Lightning Bolt?
The average width of a lightning bolt is 9 meters, but this figure is highly variable and can be highly inaccurate. The data behind this figure comes from measurements taken during experiments where bolts have been directed to travel down a grounded rod and measured with a stroboscopic camera.
The lightning bolt’s path has to be very straight for the measurements to be accurate, and this isn’t always the case when a real bolt is involved. Bolt width varies greatly depending on the conditions at the time of the strike—the temperature, humidity, and wind speed of the surrounding air, as well as the topography of the ground beneath the bolt, can all have an effect.
Why Are Lightning Bolts So Wide?
The width of a lightning bolt is thought to be due to the sheer energy of the bolt, combined with the electrical resistance of the air through which it travels. The bolt has to break the strong Coulomb force of attraction between the positive and negative charges inside it, as well as the electrostatic attraction between the positive and negative charges in the air around it.
In order to overcome these forces and travel to the ground, the bolt must generate enough energy to break its own charges apart, as well as heat the air to a temperature of 30,000 degrees Fahrenheit.
How Long Are Lightning Bolts?
A lightning bolt can vary greatly in terms of length, but on average, a bolt is about 10 kilometers long. However, this length can vary from as little as one kilometer to as many as 100 kilometers. This is due to the fact that the electric field near the tip of the bolt is much stronger than it is at the base of the bolt, meaning that the path to the ground is much shorter near the tip.
While the length of a lightning bolt is obviously too long to be measured accurately, scientists have found ways to get around this by creating a simulation of a single lightning strike.
Where are Lightning Bolts Fairly Wide?
The path to ground is shorter over water, so lightning bolts travel much further over lakes, seas, and oceans than they do over land. While the average width of a lightning bolt is 9 meters, this increases to as much as 25 meters when the strike occurs over water. In addition, the width of the bolt increases with the size of the water body on which it occurs, the larger the water body, the wider the bolt will be.
For example, the width of a lightning bolt that occurs over the Pacific Ocean could be as high as 100 meters, while the width of a bolt that occurs over a small puddle might be just 3 or 4 meters.
When Are Lightning Bolts Narrow?
The path to ground is much shorter up a tall tree where there is a lower amount of resistance than there is at ground level. As a result, a lightning bolt that travels up a tall tree might only be as wide as 2 meters, or even less. A lightning bolt that travels along the power lines or telephone lines might also be fairly narrow, as there is less air to heat and ionize along these paths.
The width of a bolt that travels along a metal rod is often just 1 meter, though this can vary depending on the length of the rod.
When you break it down like this, it becomes clearer why scientists have such difficulty measuring this natural phenomenon accurately and consistently. If a bolt is traveling along a tall tree or power line, it will be comparatively narrow.
However, if a bolt is traveling over a large lake or ocean, it will be comparatively wide. The only real way to measure the width of a lightning bolt accurately and consistently is to create a simulation of a single strike, but even this method is not immune to error.