Lightning Basics – Creation and Classification.
Lightning is a natural phenomenon that can be beautiful and deadly at the same time. In this article, we will give an overview of the physics behind how lightning is created, as well as how they are classified by scientists.
How Lightning is Created
Lightning is created when cold air meets warm air meet to create thunderstorm clouds. Since there are ice crystals in the cold air and water droplets in the warm air, the two bump together to create static electrical charges in the cloud.
Like all electrical charges, there is a positive charge and a negative charge. The positive charges stay at the top of the cloud while the negative charges stay at the bottom of the cloud. When enough negative charges accumulate at the bottom, a bolt of energy comes out to become a lightning bolt. Multiple lightning bolts often combine into a single lightning flash which moves very rapidly.
When the lightning bolt is formed, it can either travel cloud-to-cloud or from the cloud to the ground. As they travel around, electromagnetic pulses are emitted and can be detected by lightning detectors. Additionally, this bolt of lightning will also heat up the air surrounding it. The heated air will then spread around to make the distinctive thunder sounds.
Common Types of Lightning
There are many different types of lightning. However, the most common type of lightning are the ones that travel between clouds and the ones that travel from the cloud to the ground. The lightning that travels between clouds is called cloud flashes, while lightning that travels between the cloud and the ground is called cloud-to-ground, or ground-to-cloud flashes depending on the direction in which the bolt travels.
Cloud-to-ground and ground-to-cloud lightning differ in terms of how they occur. For cloud-to-ground types, it occurs naturally due to normal electrification in the environment and travels from the cloud to the ground. They can have a negative or positive charge. The negatively charged lightning is abbreviated as –CG while the positively charged lightning is abbreviated as +CG. Negative CGs are more commonly observed during a thunderstorm and can be distinguished by their downward branching shape. Positive CGs, on the other hand, are less common and can be visually identified by their lack of branching in the stroke.
Ground-to-cloud types are triggered artificially and travels from the ground to the cloud. This occurs when an upward stroke from an object on the ground jumps toward the electrically charged thunderstorm clouds. They are a lot more dangerous as they can strike tall manmade structures such as towers and airplanes. They can also be positively or negatively charged like their cloud-to-ground counterpart.
Other Types of Lightning
Besides the common cloud to ground flashes, there are also less common types of lightning that have been observed by scientists. Two of them are intracloud lightning and anvil crawlers.
Intracloud lightning is similar to cloud-to-cloud lightning, but instead of jumping between clouds, they travel between different regions of a cloud that have different charges. They can be observed as a sheet of light covering the entire sky and cannot always be seen from the ground.
Anvil crawlers is another less common type of lightning that has been observed in nature. They move slowly compared to other types of lightning and often travel very far distances. They also occur at higher altitudes than other types of lightning and appears within the clouds.
Highest Regions of Lightning
For many years, historical data on lightning strikes has been maintained by scientists for research purposes. NASA, for one, has been keeping a map of lightning strikes that have occurred around the world since 1998. Based on the data, it can be observed that the highest frequency of lightning strikes occurs in Venezuela and in the Democratic Republic of the Congo. Generally, warmer land areas also tend to attract more lightning and would benefit from the services of a lightning detector.