IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, Dr. Angela Rasmussen joins us to fact-check the news surrounding the Delta variant. But first, the Pacific Northwest was hit with a record-breaking heat wave this week, with temperatures rising as high as 116 degrees Fahrenheit in Portland, Oregon. And experts say, of all the extreme weather events brought on by climate change, heat waves stand to do the most damage to the environment, infrastructure, and human health. Here to tell us more about the alarming impacts of such extreme heat is Umair Irfan, staff writer for Vox. Welcome back, Umair.

UMAIR IRFAN: Thanks for having me, Ira.

IRA FLATOW: Nice to have you. It seems like the whole country was experiencing a heat wave this week. But as I said, the Pacific Northwest and Canada was really hit hard. The numbers are staggering. At least 79 people are confirmed dead from the heat wave in Oregon. And the New York Times is reporting hundreds of heat-related deaths in British Columbia. What happened here?

UMAIR IRFAN: Well, we saw a lot of heat records being broken across the Pacific Northwest. And as you noted, this is remarkable because this is an area that normally doesn’t see this kind of heat. And that’s part of why the impact has been so great. What we saw here was essentially a very large high-pressure system that settled over the area and allowed heat to accumulate.

And we saw heat records being broken by whole degrees. Typically, heat records are broken by fractions of a degree. But some of them were beat by 6, 7, 8 degrees Fahrenheit. And this heat also comes after another heat wave across much of the Southwestern United States. And across Canada and the Pacific Northwest, we’ve seen, as you noted, hundreds of people dying.

One case in point is this small town in British Columbia called Lytton where 250 people normally live, and it broke heat records three days in a row. And then, after that, it experienced a fire that basically burned down the whole town. It reached temperatures of 121 degrees Fahrenheit, which is hotter than Las Vegas has ever gotten, and it’s 1,000 miles north of that city. So it just shows you just how unusual the temperatures have been and how high they’ve gotten.

IRA FLATOW: The temperature and then the destruction by the fire– I heard about that. That’s an incredible story. And also, the news this week has put a new term for that high-pressure system, a heat dome, right?

UMAIR IRFAN: Yeah, that’s right. I mean, one thing to remember is that heat waves are a distinct meteorological phenomenon. It’s not just that temperatures are going up in the summer. What happens is you have a column of air that’s pressing down over an area, this high-pressure system or an anticyclone. And as that air sinks, it compresses and heats up, and it traps the heat that’s closer to the ground, acting as, as you said, a heat dome.

And when that happens, it also squeezes away moisture so clouds and air precipitation don’t form. And what that means is that the sun has an unobstructed line of sight to the ground. And then this heat dome acts as a greenhouse within a greenhouse, leading to higher and higher temperatures rapidly accumulating, especially in the summer where days are long and nights are short. And then you suddenly are in triple-digit temperatures.

And then this is further exacerbated across much of the West this year by an ongoing megadrought. So the moisture that would typically be in the ground to help it cool off, the same way that sweat cools off the body– that’s not there. And so there’s nowhere else for this heat to go, except into the ground and into the air.

One of the other things that we saw this week was fires starting to ignite in the wake of these heat waves. There was actually an event in Western Canada where fires started creating these plumes of clouds, pyrocumulus clouds. And those clouds actually generated lightning strikes that helped ignite more fires. And so you ended up in a situation where you had this feedback loop of heat and fire igniting even more fires.

IRA FLATOW: And you mentioned speaking of shorter nights this time of the year. And you’re reporting that there’s little relief from the heat at night, when typically temperatures should be dropping a bit.

UMAIR IRFAN: Right, one of the most distinct signals we see with climate change, in addition to seeing more frequent and intense heat waves, is that nighttime temperatures are rising. The lows are actually rising faster than the highs. And that has huge consequences for human health because without nighttime temperatures dropping off enough, people have less relief from the heat. And so that leads to a larger accumulative heat exposure. And that’s associated with more severe outcomes from heat, things like heat exhaustion, and heat stress, and other health maladies that are worsened by just being in warmer weather for a longer time.

IRA FLATOW: Are people out there who are experiencing these heat problems they never had before– are they considering this permanent, the new normal for them, and something that they have to prepare for?

UMAIR IRFAN: I mean, certainly, that’s on a lot of people’s minds. Yes, frequency and intensity of heat waves is going up, and the cooler regions of the planet are actually warming faster than the hotter regions. So people living at northern latitudes are seeing a larger change, a larger differential from their typical average than people even closer to the equator, even though the temperatures in, say, the desert Southwest of the US may actually go higher. And that does mean that people need to start to adapt.

One is that people have to be more aware of things like heat stress and understand the warning signs of heat exhaustion and other kinds of heat-related illnesses, but infrastructure also needs to be upgraded and adapt. And we’ve seen with the heat wave this week, somehow, where all these failures are starting to occur. You have power lines that can’t transmit power as efficiently. We’ve seen roads buckling. We’ve seen water systems starting to leak. And all this can add up to a disaster that ends up being much worse than any individual component.

IRA FLATOW: That’s true, because I saw this stunning photo this week where the heat had melted one of the power cables in Portland’s streetcar system.

UMAIR IRFAN: Yeah, that’s right. The power system is one of the things that’s most severely stressed by this. On one hand, you have a huge demand spike because of people switching on their air conditioners and trying to cool off. And then, on the supply side, power systems, the power generators themselves are stressed. There are power plants that actually have to shut off when water temperatures get too high because that water is too hot for them to cool off with. And then the power lines themselves become less efficient in transmitting electricity.

So you have both a supply crunch and a demand increase. And we actually saw on the East Coast in New York City where they sent out an alert asking people to turn down the power just as temperatures were rising, because they were concerned about outages being spurred by this. And so this is something that is going to be a problem across the country, but is especially acute in places like the Pacific Northwest that don’t see these kinds of heat spikes.

And one other thing to note is that in an area like Seattle, that’s the least air-conditioned metro area in the US. Fewer than half of the homes there have ACs, and the ones that do have ACs are not usually up to the task of cooling triple-digit temperatures. So it has to be adapted not just for simply cooling off, but being able to cool off from these very high extremes.

IRA FLATOW: Yeah, I know that President Biden’s infrastructure plan is making its way through Congress. He’s talked about this, and people have talked about, well, when you talk about an infrastructure, you have to take into effect that there is climate change. There’s a climate crisis going on, and you need to prepare for these kinds of situations as a result of that.

UMAIR IRFAN: Yeah, that’s right. You have to think about both adapting to climate change and mitigating it. So you don’t just want to reduce greenhouse gases, but you also have to understand that the world that you’re going to be living in is going to be drastically different over time. Things like power infrastructure, power lines and power plants– those have to be built to withstand decades of use. And in those decades, we’re going to be expecting temperatures continuing to rise. We’re going to expect power demand continuing to rise as well. And we need to be able to compensate for that and start building for those stresses now. Otherwise, we’ll be seeing more failures in the future.

IRA FLATOW: Thank you, Umair, interesting stuff as always. Umair Irfan is staff writer for Vox.

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With temperatures in many places in the triple digits, can it get too hot for planes to fly? My next guest says yes. Rhett Allain is associate professor of physics at Southeastern Louisiana University and a popular Dot Physics blogger at Wired Science Blogs Rhett, welcome back to Science Friday.

RHETT ALLAIN: Thank you.

IRA FLATOW: Let’s get right into this, because I remember reading a piece you wrote back in, what, 2017, the heat wave back then, describing how it can get too hot for airplanes to take off. Tell us why that is.

RHETT ALLAIN: I mean, I was surprised, too. I saw that, and I’m like, what? That’s weird. But it is true. When the weather gets too hot, some of these planes can’t take off. It has to do with the way that planes fly. When the plane wing flies and it’s tilted at some angle, it collides with these molecules, right?

These then change momentum. And because they change momentum, they push on the wing. So if you think of a plane wing flying and just pushing through the air and deflecting these air molecules down, this produces an upward thrust on the plane, and it explains how the plane can fly. I like that way better because it’s more fundamental physics.

IRA FLATOW: It’s more physics. It’s like a rocket ship. Air goes down. Plane goes up.

RHETT ALLAIN: It’s exactly like a rocket ship. That’s right.

IRA FLATOW: So what happens when the air gets too hot then?

RHETT ALLAIN: Well, when the air gets hot– what is hot air? We like to think of temperature as associated with the motion of the particles in the air, the nitrogen molecules and the oxygen molecules. And as you increase the temperature, these molecules move faster and faster and faster. And when they do that, they spread out. So you decrease the density of the air when it’s hot.

And it doesn’t always feel that way, but that is true. There’s lower density air with higher temperature. And that means there’s fewer of these air molecules to collide with the wing, and you get lower lift with lower density air. You could compensate for that by flying faster, but that would take a longer runway. And then that’s where we get into a safety issue for some planes. They don’t have a long enough runway to make sure that they can get to take-off speed.

IRA FLATOW: And so you just have to wait till it gets cooler before you can take off.

RHETT ALLAIN: Yeah, someone told me that a lot of flights into Las Vegas in the summer are morning and evening because it’s not so hot. If it’s too hot in the middle of the day, then a lot of these planes just don’t have the safety clearances to take off.

IRA FLATOW: I didn’t hear any reports of mass groundings of airplanes this really hot week we’ve been having. Do you expect this to happen sooner or later?

RHETT ALLAIN: Oh, yeah, as we deal with the hotter and hotter temperatures, you have an option of either changing planes– some planes can take off with that– or getting a longer runway. But both of those aren’t really easy to change real quick. It’s easier just to ground the plane and wait till it’s safe to fly again.

IRA FLATOW: We always hear about the unexpected consequences of climate change and what things are going on, about plants and heat and hurricanes, but we never think about affecting the airline industry.

RHETT ALLAIN: Right, and we depend on that a lot. In general, we fly a lot. And we travel a lot by plane because it’s a lot quicker than cars. And then it is a problem. So we need to address climate change, but we probably also need to address airline travel. It’s not necessarily always the best mode. High-speed trains wouldn’t have this problem.

IRA FLATOW: I’m with you on that one. Let’s see if we can get more of them to cross the country.

RHETT ALLAIN: Yeah, I’d like that, too.

IRA FLATOW: Yeah, well, thank you for explaining us the physics of flight, Rhett.

RHETT ALLAIN: Oh, thank you.

IRA FLATOW: Rhett Allain is an associate professor of physics at Southeastern Louisiana University and a popular Dot Physics blogger at Wired Science Blogs.

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