This Is How You Mathematically Predict Lightning Strikes

Soon, it's very possible that when you say something like "you have better odds of being struck by lightning," that won't necessarily mean it's all that rare. And there's a good chance that you'll be able to tell that person (roughly) what the odds of that happening are.

Let me explain. Lightning is expected to increase along with global temperatures. The problem is, scientists haven't known by how much, because it's really hard to make a lightning prediction model. But now, for the first time, it looks like researchers at the University of California-Berkeley have figured out exactly how to predict and model lightning strikes around the country.

Turns out, it's not insanely complicated, provided you have the correct inputs. In fact, it's a simple multiplication problem. Lightning flash rate per area is equal to precipitation times the area's potential electrical energy. In equation form, it looks like this:

In this equation, F is the lightning flash rate per area, P is the precipitation rate, and CAPE is the area's "convective available potential energy," a measure that's pretty commonly used in meteorology. It's basically a measure of atmospheric instability (useful for determining when bad weather is going to hit, which makes sense), and it's a measure of how buoyant the air is—that is, how fast it can be sucked up into the upper atmosphere.

The h over E is the "constant of proportionality" and because it doesn't change let's not worry about it.

So, where do you get these inputs? There are a series of weather monitoring stations around the country that grab CAPE, and precipitation is taken from similar stations.

When lead research David Romps, whose team's work was published in Science, took this equation and compared it to actual data from 2011, it lined up quite closely.

"We were blown away by how incredibly well that worked to predict lightning strikes," he said in a statement.

"This map of CAPE x P bears a close resemblance to the map of lightning flashes," he wrote in the paper. "This distribution of flashes is similar to the long-term annual mean."

So we've now got the best model for predicting lightning flashes. What does it say? Well, we've known for a while now that lightning strikes are likely to increase along with global temperatures. But estimates have varied widely—some scientists think it'll increase just a couple percent, others say it'll more than double.

There's not a whole lot of noise in Romps's estimates: CAPE is something that can be predicted out fairly easily: "All [models] in our ensemble predict that [the United State's] mean CAPE will increase over the 21st century, with a mean increase of 11.2 percent per degree Celsius of global warming," he wrote. "Overall, the [models] predict a ~50 percent increase in the rate of lightning strikes in the United States over the 21st century."

That's not a good thing, considering that lightning strikes are the leading starter of massive wildfires.