Comment Thunderstorms are a staple of summer in the Lower 48, and they all produce lightning—a wild phenomenon that can also be dangerous. In DC on Thursday, two people died after being treated for injuries sustained in an apparent lightning strike near the White House. These bolts of raw electricity shoot through the air, shoot from stormy skies and blast whatever they hit with a deafening roar. Lightning can be magical, dangerous, beautiful and terrifying, but how much do you know about what happens when there is a strike? Two killed by lightning Thursday night near the White House Lightning is an electrical discharge and nature’s balancing mechanism for distributing charge throughout the atmosphere. Thunderstorms become electrified when electrons, which are negatively charged particles, are sheared off a water particle—such as a raindrop, snowflake, or hailstone—and land on another, leaving the former with a net positive charge and the latter a little extra negative. . In general, ice crystals acquire a positive charge, while raindrops acquire a negative charge. This makes the top of a cloud, where the temperature is well below freezing, positively charged. Below that is a more extended “central negative” within the storm. A shallow, broad positive charge sits at the base of the storm like the bottom of a hamburger bun. Most of the lightning we see is either intracloud (within the cloud) or in the form of cloud-to-ground bolts, usually from from the middle negative charge. The greater the electric field within a cloud, the more “sparky” the storm will be. Getting an electric spark to jump in the air is difficult. The ambient electric field must be large enough to overcome the “dielectric breakdown strength” of air. Consider a dam. It prevents water from flowing past it unless the volume of water behind it reaches a threshold sufficient to burst the dam. Then the stored water can leak out unhindered. For air, that magic number is 3 megavolts (or 3 million volts) per meter for dry air (it will change some in a storm). The charge that builds up on the surface will begin to bleed out into the thin air in a thin stream of electrons known as a “corona” discharge. This heats the adjacent air, reducing resistance and making it possible for this spark to propagate in jagged increments. It’s unclear what processes unfold within a cloud, but eventually what’s called a “step leader” of electricity races toward the ground, jumping in a branching, fractal pattern. What I learned from 20 years of photographing lightning in DC “Ascending streamers” or narrow conduits of electricity reach skyward from the surface, similar to a group of students raising their hands. Finally, the downward conductor connects to one of the upward streamers to create an unbroken channel of electricity between the cloud and the ground. Current pulses pass through the channel, causing a burst of light. That’s why lightning seems to flicker.
Surprising facts about lightning
Lightning isn’t that fat. In fact, it’s only an inch or two wide. It just looks wider because of the brightness. Lightning is five times hotter than the surface of the sun. Inside this narrow lightning channel, electricity heats the air to nearly 55,000 degrees. This causes a rapid expansion of the air, which produces the atmospheric shock wave we hear as thunder. Lightning can be triggered. Researchers at Los Alamos National Laboratory in New Mexico use rockets to trigger lightning and then use high-speed cameras and instruments to collect data. It has also been proven that airplanes, helicopters, tall man-made structures, and even wind turbines can trigger their own strikes. “Lightning up” is one thing. It is exactly what it sounds like — lightning that jumps from the ground into the cloud, fanning outward along the extended lower positive charge of the cloud. In fact, self-propelled risers are common from man-made transmission/broadcast towers and are an area of emerging research. Some lightning strikes are more likely to start fires. Although lightning is extremely hot, it is also short-lived. This limits the window of opportunity for a fire to start. But instead of current flowing between the sky and the ground in a short series of staccato bursts, some lightning takes the form of a “direct current” discharge. This means that the current flows in longer pulses. Because the current heats the ground over a longer period of time, the chances of a fire go up significantly. Men are hit about four times more often than women. In the United States, men account for 84% of lightning deaths and women make up the remaining 16%. Lightning accidents are on a downward trend. Due to improved forecasting, education and awareness, lightning deaths have decreased significantly in recent decades. An average of 43 people were killed by lightning per year in the United States between 1989 and 2018, but the average dropped to 23 between 2012 and 2022. 2021 saw a record low of 11 deaths.
Tips and facts to know to stay safe during lightning
Never take shelter under a tree. If lightning strikes a tree, the charge can flow through the trunk and laterally strike people below it or also spread to the ground. Many lightning tragedies have resulted from people seeking shelter under trees. The previous DC lightning accident, which occurred on May 17, 1991, occurred when a team took cover under a tree during a lacrosse game. Recreational activities — especially fishing and boating — are the biggest sources of death from lightning. “[F]Pilots and boaters are likely to be exposed and more vulnerable to direct lightning,” a report from the National Lightning Safety Council from 2020 said. Lightning can strike even in snowstorms. Thundersnow is real and can be dangerous. On January 25, 1990, lightning struck a light pole during a snowstorm in Crystal Lake, Ill. The cargo traveled across the icy ground and injured 11 people who were nearby shoveling snow or pushing stranded motorists. Lightning can travel 10 or more miles away from a parent storm and even hit in fresh air away from any rain. These “bolts from the blue” are often more powerful and powerful, coming from the positively charged top of a storm. These are among the most dangerous, as they can strike in otherwise calm conditions. That’s why experts recommend taking shelter at the first sign of thunder, as that’s a sign you’re close enough to be struck by lightning. Ninety percent of lightning victims survive. An average of 30 lightning deaths occur in the United States each year. Lightning near the White House on Thursday brought the death toll to 11 this year.
Read more about lightning… “Giant jet” lightning is a mystery. These researchers are solving it. Jonathan’s story: After a tragic ‘bolt out of the blue’, two simple rules that could save your life Bolts from the blue: See how lightning can strike when a storm is dozens of miles away Where lightning struck the most in the US in 2021
