Yes, It’s Hot. But How Hot?

12:15 minutes

Park visitors to NYC bake in the sun
Credit: Shutterstock

Much of the country has been enduring a heat wave this week, with millions sweating from Maine to the Midwest. But describing exactly how hot it is—and when temperatures become hazardous—can be challenging. Beyond the basic temperature, there’s the heat index, invented in 1978, which incorporates humidity measurements and is supposed to give a better indication of how a person might feel outside. Some health researchers are calling for more attention to a different type of temperature measurement known as the wet bulb globe temperature. It tracks temperature, humidity, and sunlight, and improves upon the heat index standard.

Umair Irfan, senior correspondent at Vox, joins SciFri’s Kathleen Davis to talk about measuring temperatures and protecting yourself from extreme heat. Plus, they discuss other stories from the week in science, including advances in tornado prediction, a delay in a return flight from the International Space Station, and a newly-described horned dinosaur that once roamed the US.

Sign Up For The Week In Science Newsletter

Keep up with the week’s essential science news headlines, plus stories that offer extra joy and awe.


Segment Guests

Umair Irfan

Umair Irfan is a senior correspondent at Vox, based in Washington, D.C.

Segment Transcript

KATHLEEN DAVIS: This is Science Friday. I’m Kathleen Davis.

JOHN DANKOSKY: And I’m John Dankosky. Later this hour, the challenges of facing a global issue like climate change on the city and municipal level. Plus, efforts to find and identify lost birds using citizen science. But first–

KATHLEEN DAVIS: You don’t need me to tell you that it is hot outside. People along the East Coast and deep into the Midwest have been enduring a heat wave. Sticky, sweaty, and gross. And while you can look at your trusty thermometer or check the heat index, is there a better way to keep track of summertime heat stress? Well, joining me now to talk about it is Umair Irfan, senior correspondent at Vox in Washington, DC. Welcome back, Umair.

UMAIR IRFAN: Hello, Kathleen.

KATHLEEN DAVIS: So tell us about this other temperature measurement that we could be using. Is this a better heat index?

UMAIR IRFAN: Well, according to a lot of people that use it, yes. This is probably the most effective way of assessing heat damage to the body. And this was actually a measurement developed by the US military in the 1950s. It’s known as the Wet Bulb Globe Temperature. And what it does is it accounts one, for air temperature, but also for humidity and how well sweat evaporates from the body as well as sunlight exposure.

So it incorporates three or four different measurements into one number and tells you more accurately the threshold at which the human body starts to experience danger. The danger limit under the Wet Bulb Globe Temperature is usually considered to be about 95f, and after six hours or so, that’s considered to be extremely dangerous.

KATHLEEN DAVIS: I have to say, Wet Bulb Globe Temperature doesn’t really roll off the tongue, but I digress. Is this something that I can measure myself? Or do I need, like a special thermometer for this?

UMAIR IRFAN: Well, the measurement devices actually incorporate these three or four different measurements together. So one, it is a conventional thermometer, but it also has a thermometer inside a black globe, essentially, to serve as a proxy for exposure to sunlight. That’s the globe.

And then the wet bulb is a thermometer that’s wrapped in a wet cloth. And what that does is it shows basically, as long as the cloth is wet, it means that sweat or it means that water is not evaporating. And if that gets way too hot, then that means that your body cannot sweat effectively. It takes in more energy from the surroundings than it can dissipate. And that can lead to complications like heat exhaustion and then later heatstroke.

KATHLEEN DAVIS: Is this being used by anyone right now?

UMAIR IRFAN: It’s used by a lot of sporting teams. You know, there’s a lot of high school and college athletics associations that use the Wet Bulb Globe Temperature as a threshold for whether or not they’re going to have outdoor activities. The military uses this as well. They usually consider Wet Bulb Globe Temperatures above 90 degrees to be considered black flag temperatures.

But this is not something that’s widely reported. It’s also not something that’s talked about in the news. And a lot of employers don’t really pay attention to this. Like, you know, farm workers and other kinds of jobs sites where you have people being outside, they typically rely on just the temperature or the heat index, which doesn’t tell the full story about the risks that the people working outside will face.

KATHLEEN DAVIS: If I’m going out expecting it to be 80 degrees, but then it feels a lot more like 95, I mean, that’s going to put a stress on my body that I wasn’t expecting.

UMAIR IRFAN: Yeah, that’s right. And part of the challenge here is that while any individual metric is going to be covering over a wide area, the way we individually experience stresses from heat can vary a lot person to person. So your threshold for heat exposure can be very different from mine, even under the same conditions, especially if you’re taking some kinds of medicines, if you’re an older adult or if you’re a very young child, and other kinds of factors– how much cumulative exposure you’ve had. All of these other factors also play a risk in how quickly you can succumb to the heat.

KATHLEEN DAVIS: OK. Let’s talk about some other weather news. This has been a really busy season for tornadoes. Do we know why this is?

UMAIR IRFAN: There appear to be a few different factors at work. You know, tornadoes are very mercurial. They spool up very quickly. And from an atmospheres perspective, you know, they’re very small. But it appears that there are some other factors globally that are playing a role in the current round of tornadoes, including the rash of tornadoes we saw over Memorial Day weekend.

One big factor that appears to be at work is this switch from El Niño to La Niña in the Pacific Ocean. This is the warming pattern at the surface of the Pacific Ocean. And it starts to shift the jet stream over the United States, and it starts to lead to atmospheric instability that allows tornadoes to form a little bit more readily.

There are other kinds of ocean patterns that are emerging from the Indian Ocean. This is a pattern known as the Madden-Julian Oscillation that’s sending waves of disruption over to the United States. That’s also leading to increased tornado activity. Plus, it’s been really hot in Central America and over Mexico, and that’s led to more moisture in the atmosphere. And that moisture helps fuel thunderstorms that can then spawn tornadoes.

KATHLEEN DAVIS: Is there anything that we can do to better predict tornadoes?

UMAIR IRFAN: Well, scientists say that they’ve actually been making a lot of progress in getting ahead of tornadoes. Right now, most tornado warnings, you get them on the order of minutes, maybe 10 minutes, sometimes even less. But there are warning signs that clusters of tornadoes might be emerging, you know, days in advance. And scientists have started to pick up on them, one, by studying historical data, but also by using machine learning models that can actually detect trends and patterns that scientists previously could not pick up on.

And in fact, they’re using these forecasting models and testing them out right now at the Storm Prediction Center at the National Weather Service. These machine learning models can actually anticipate storms that could lead to tornadoes up to a week in advance. You know, it can’t really tell you whether your house is in danger, but it can help airlines reroute traffic. It can help emergency responders make sure they have line crews ready to do repairs and also muster resources to deal with the aftermath. And so there’s a lot of ways you can make that useful.

KATHLEEN DAVIS: Yeah, it sounds like that could be a big deal.

So let’s shift gears here to some positive environmental news. It turns out some of the land near the Chernobyl nuclear site might actually be getting safer. Is that right?

UMAIR IRFAN: Right. The scientists who have been studying this area for a long time in Ukraine, this week, they’ve reported that the radiation levels are on the further reaches of the Exclusion Zone or some of the areas that were contaminated after the 1986 Chernobyl Nuclear Disaster have fallen below the dangerous thresholds, that basically it’s now within the safe limits for farming. And this is a huge bit of progress for the people who live in the region who rely on this land. But it just shows, though, also how long it can take for this kind of contamination to fade away, that this has been a nearly 40 year long process waiting.

Now, there are other complications that have emerged around this as well. Basically, there’s still the stigma of food that’s grown in these radiation zones, and people here want to export that food. Particularly since Ukraine lost a lot of farmland during Russia’s invasion of Ukraine, they want to use this to compensate that and to bolster their export capacity. But they want to also convince their customers that this food that they’re growing on this land is safe.

KATHLEEN DAVIS: Yeah, that seems like a big hurdle.

So let’s get back a little bit closer to home. So we’ve all heard a lot over the past few years about weight loss drugs and their use in adults. But there are other interventions that are now being recommended for kids. Can you walk me through what’s being discussed here?

UMAIR IRFAN: So roughly between one in five and one in six children in the US are classified as obese, and that’s considered being in the 95th percentile or above for their body mass index given their age and sex. The US Preventative Services Task Force– this is an independent body of experts that analyzes research and advises the government– they’re now recommending that intensive behavioral intervention should be used for kids who are six years of age and older.

Basically, the idea is that kids should be receiving things like counseling, education, and supervised exercise as a way to deal with obesity. And they found that the evidence shows that this does bear out, that basically roughly around 26 hours of counseling and supervision leads to measurable and sustained weight loss.

KATHLEEN DAVIS: So before this, was there any sort of counseling intervention being done?

UMAIR IRFAN: There was on an ad hoc basis, but it was not a recommendation. This group basically was looking at what the evidence shows of what actually works. Now, they say that there is actually a body of evidence that shows that counseling can be very effective for children.

KATHLEEN DAVIS: And this sounds like this would be a lot less invasive than maybe some of these weight loss drugs that are being used in adults, right?

UMAIR IRFAN: Right. And that is part of the advantage here as well. The task force says that they did look into using these GLP-1 agonists like Ozempic and their effects on children, but said that the evidence wasn’t quite there yet, and there isn’t enough research to issue any kind of recommendation one way or another. But counseling seems to be a very low stakes way of creating some meaningful gains here and now. That’s why it’s the new default.

KATHLEEN DAVIS: So let’s shift gears again and head to space actually. So over the past few weeks, we’ve talked about the challenges of getting Boeing’s Starliner spacecraft off the ground. And now that it’s at the International Space station, there may be another glitch.

UMAIR IRFAN: So the two astronauts who arrived at the International Space Station on the Boeing Starliner, they arrived on June 6 and they were only supposed to stay for about a week. But this week, NASA says that they’ll be there at least until June 26. And that’s because they want to try to figure out what went wrong during the trip there. Basically, on the way to the spacecraft, they experienced helium leaks and they saw thrusters malfunction. And the engineers are trying to troubleshoot and figure out what went wrong in order to make sure that the next trips there go safely.

Now, they say that the spacecraft is safe, that it’s perfectly capable of taking the astronauts home. It’s just that the parts that were malfunctioning are on parts of the spacecraft that are considered disposable, or parts that would be damaged or destroyed during reentry by design. And so this is their last chance to try to figure out and examine these parts and see if they can figure out what went wrong.

KATHLEEN DAVIS: Well, that sounds like my personal nightmare. So I hope that they figure that out and get them back home safely.

Finally, we have one last story that I’m very excited to talk about. There is a new flashy dinosaur in town, it sounds like?

UMAIR IRFAN: Right. So scientists just this week have declared that there’s a new dinosaur called lokiceratops. It’s a herbivore. It lived in the swamps and flood plains of Montana about 78 million years ago. It’s a cousin of the triceratops, but one, it’s really big. This is the biggest dinosaur of this family that they found so far, 22 feet long, weighing about 11,000 pounds. It’s also the most flamboyant. That’s kind of the description that the scientists–

KATHLEEN DAVIS: Is that a scientific term?

UMAIR IRFAN: It’s not a scientific term, but I mean, they talked a lot about how many horns and how ornate its crest was. This is a dinosaur that had two asymmetrical horns on the side of its frill and more than 20 little horns around the side of its head. It’s very big. And it also indicates, though, that there was a lot more diversity of this family of dinosaurs in the United States in this region millions of years ago, and also that many of these dinosaurs were living alongside each other.

These fossils were originally discovered in 2019, but only recently did they finally do enough analysis, piecing the parts together, to realize that this is actually a new species.

KATHLEEN DAVIS: So what do they think that it was? Like a mutant triceratops or something?

UMAIR IRFAN: I mean, that’s a possibility. You know, when you’re looking at fossils, you’re looking at fragments. And so tend to try to see if they fit into any existing categories before deciding that they’re in a new category. And so it required a little bit more searching and figuring out, you know, like, is this just simply a really, really big triceratops? Or is this actually a different species entirely? And that’s a process that takes a lot of time. And they finally came to the conclusion this week that this is, in fact, something new.

KATHLEEN DAVIS: Well, that’s all the time that we have for now. Umair Irfan, senior correspondent at Vox in Washington, D.C. Thanks again for being with me.

UMAIR IRFAN: My pleasure, Kathleen. Thanks for having me.

Copyright © 2024 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/

Meet the Producers and Host

About Charles Bergquist

As Science Friday’s director and senior producer, Charles Bergquist channels the chaos of a live production studio into something sounding like a radio program. Favorite topics include planetary sciences, chemistry, materials, and shiny things with blinking lights.

About Kathleen Davis

Kathleen Davis is a producer at Science Friday, which means she spends the week brainstorming, researching, and writing, typically in that order. She’s a big fan of stories related to strange animal facts and dystopian technology.

Explore More