Springtime storms can often bring an impressive light show to South Central Texas, just like the lightning that’s been found in the storm activity over the past few days.
Photos sent into KSAT Connect (included below) show an electric sky, with various types of lightning strikes observed.
What exactly are the most common variations of lightning strikes and how do they form? Let’s dive into the science below:
FIRST OFF, HOW DOES LIGHTNING FORM?
As a thunderstorm grows and matures, cold air at the top of the cloud forms ice crystals, while the warmer air at the bottom of the cloud forms water droplets. Within that storm, the ice crystals and water droplets bump up against each other, which in turns creates static electrical charges in the cloud.
A positive charge develops at the top of the cloud, while a negative charge develops at the bottom. As the charge at the bottom of the cloud grows and strengthens, energy is eventually let out in the form of a lightning strike to an area or object of the opposite charge.
According to the National Weather Service, an intra-cloud strike is the most common type of lightning. The strike happens completely inside the cloud and jumps around between different charge regions, lighting up the cloud in a bright light color.
Cloud-to-ground lightning is essentially just that: a lightning strike that reaches out of the cloud and strikes an object on the ground.
In most scenarios, negatively charged energy is released from the base of the cloud, and causes positively charged energy from objects on the ground to reach upwards (especially from taller objects like trees, towers, and buildings). When these two charges connect, a current begins flowing and a lightning bolt develops.
POSITIVE VERSUS NEGATIVE STRIKES
We often get this lightning counter question during live storm coverage on the KSAT Weather Authority App: What is the difference between positive and negative lightning strikes?
- Negative Strike: The more common type of cloud-to-ground lightning strike that forms at the base of the cloud, where a negative charge is located.
- Positive Strike: The less common type of cloud-to-ground lightning strike. Positive strikes form in the higher levels of the cloud, where there is a positive charge. This type makes up for less than 5% of all lightning strikes, but is typically stronger than negative strikes since there is more air to burn through to reach the ground. That means that electric fields with positive strikes are also much greater than negative strikes, and can cause more damage when it comes to starting forest fires and causing power outages.
Cloud-to-cloud lightning is lightning that stretches from one cloud to another and doesn’t strike the ground.
GROUND-TO-CLOUD: “TRIGGERED LIGHTNING”
This type of lightning is artificially triggered upwards by tall structures like buildings and towers. In this case, lightning strikes initiate at the top of these structures and travel up into the cloud, usually occurring after a natural lightning flash.
Spider lightning consists of long lightning bolts that travel horizontally. According to the National Weather Service, this type of lightning is often linked to a positive cloud-to-ground lightning flash.
BOLT FROM THE BLUE
A “Bolt from the Blue” lightning strike is a cloud-to-ground strike that forms inside the cloud. The bolt then exits the storm (while it’s still in the air) and travels away from the cloud horizontally. These strikes can travel miles away from the parent thunderstorm before finally touching the ground, which is why it’s still dangerous to be outside even when it’s not raining directly over you.
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