But these aren’t ordinary lightning bolts. They’re the elusive upward lightning.
A slowed-down video reveals the curious orientation of the bolts. Frame by frame, it’s easy to see the inch-thick tendrils of electricity leaping from the tips of buildings as drenching rains sweep through the city.
All towers struck were more than one thousand feet tall.
When powerful positive cloud-to-ground lightning strikes, it quickly enhances and disrupts the electrical field nearby. That can trigger a positive upward leader to hop off objects to neutralize the charge imbalance. One can make out the dendrite-like horizontal branches as the lightning distributes charge throughout the cloud base.
Each pulse of light is another surge of current flowing through the channel. It’s like pinching a garden hose — intermittent bursts punctuated by lulls as the following wave washes through. A typical lightning flash can have several dozen individual rushes of electrical charge.
Most upward lightning is man-made. How? It simply wouldn’t occur in most cases if the buildings or wind turbines weren’t there. In the wintertime, tall pointed objects — such as radio/television transmission towers or skyscrapers — can focus charge and throw lightning bolts in the middle of a blizzard!
Despite how remarkable it may seem, barrages of upward lightning in Chicago have become the new normal thanks to the cluster of skyscrapers. Similar episodes happened in 2014, 2017, 2018 and probably countless other times. But it’s spectacular every time.
So next time you’re safely indoors watching a storm, keep an eye out the window on nearby tall objects. You might just catch some spectacular upward lightning.