What is a heat wave and what causes it to be so hot?

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The thermometer in Death Valley shows a temperature of 130 degrees Fahrenheit (54 degrees Celsius).

He was sweating just watching this.
Photo: Patrick T. Fallon / AFP (Getty Images)

We live in an era of endless heat. Winter or summer, Arctic or tropics, it doesn’t matter. Heat waves have become a fix of the climate crisis and modern life.

The United States faced record heat in 2021, including June which is now in the record books as the warmest ever. Temperatures across the country were 4.2 degrees Fahrenheit (2.3 degrees Fahrenheit) higher than normal, and the west was repeatedly hit by dangerous heat.

The effects of this year’s heat, let alone the heat of the coming years, are deep. Hundreds of people died in the Pacific Northwest as well it is estimated to be a billion sea creatures in the midst of record heat. The tanks have shrunk. The infrastructure has literally melted away.

The future heat will only get worse. That is why their understanding is more and more important, than exactly the heat wave (surprisingly tricky suggestion!), How to predict them in advance so that people would have warnings and only what is being prepared.

What is a heat wave?

The heat wave is, of course, when it goes crazy for a long time. But that doesn’t really cut me off from a meteorological standpoint. (Seriously, imagine books of records The Internet had its way.)

“It’s a simple question, surprisingly it’s not an easy answer,” said Karen McKinnon, a researcher at the University of California, Los Angeles.

Although heat is the main killing in the U.S. related to weather conditions, there is no standard definition or heat wave threshold. Certain temperature signs can trigger heat warnings or National Meteorological Service alerts on any day or even day. But when it comes to driving a heat wave, official glossary of the agency contains this definition:

“A period of abnormally and uncomfortably hot and unusually humid weather. The heat wave usually lasts two or more days. “

Compare this to the detailed entry on “freezing spray” in several places in the dictionary, which reads: vessel movement. “All right then.

McKinnon noted that there are several other ways to think about what constitutes a heat wave outside of temperatures hotter than the normal two days or more. It may be useful for researchers to consider which percentile the period of extreme heat belongs to. This facilitates the analysis of the data. Many of the ways we talk about heat waves also focus on daytime highs, but she noticed that the lowest temperatures during the night are just as important to watch.

“Especially for human health, it’s really important that our bodies can cool down at night,” she said. “And that’s why people who focus more on human health, heat wave definitions will often think about what happens to night temperatures as well. One way to think about this is that you might need to define the heat wave for the input you are interested in. Thus, a heat wave for human health could be different from, say, a heat wave in terms of impact on crops. “

How do heat waves form?

Well, it depends on how much time you have. The short answer is in many ways. The longer answer is that it depends on how deep you want to go.

High pressure areas are often to blame for the heat, especially in summer. They can lock in the persistent sunny sky and actually amplify as the heat radiates from the ground, locking in more pressure. There is even a term for it: heat domes. This is the setting that led to the deadly Pacific Northwest Heat Wave in June 2021. But local topography may also play a role.

“At PNW, the Cascade Mountains helped raise the temperature as warm air“ descended down the mountain ”thanks to an east wind from high pressure clockwise,” Kathie Dello, a North Carolina state climatologist, told Twitter DM.

Sometimes wild zigzags in a jet stream can also help heat flow from lower latitudes to colder regions in the north (or south, depending on which side of the equator you are on). In fact, when the jet stream becomes really wavy, it can actually help researchers predict where heat waves will form. You can imagine a jet stream like battle ropes in the gym which people use to practice weapons. When you use these ropes, it can send oscillations from your fluttering hands down the line, and you can control whether they make big or small oscillations.

So it is with the jet stream. All sorts of interference, whether it’s a tropical cyclone in the Western Pacific or a large high-pressure area elsewhere, can cause the jet to oscillate like gym ropes. And these oscillations are set in predictable numbers. As a result, you will often have various hotspots around the world. For example, during the Pacific Northwest heat wave, there were some glowing temperatures in parts of Europe.

“Extremes are not unique,” McKinnon said. “They’re usually located.”

Great news for forecasters, but maybe bad news for disaster managers (or your humble extreme weather correspondent) because that means you have to potentially juggle multiple crises at once.

Climate change amplifies heat waves

It may not be shocking that climate change (so-called global warming) is leading to a worsening of the heat. But it might be surprising that warming up to about 1.8 degrees Fahrenheit (1 degree Celsius) had too much of an impact on the frequency and severity of heat waves.

“Our background state is changing,” Dello said. “So when we talk about warming up by a few degrees on average, we get there by having more hot days. As we continue to add heat-trapping gases to the atmosphere, we see how sensitive the climate is and it has unprecedented heat. “

Scientists often refer to this idea that climate change is similar filling cubes therefore, extreme weather is more likely to occur. However, I would like to suggest a new analogy. It’s like replacing the dice completely. Instead of offering 1 to 6 on a six-sided dice, our new dice run 2 to 7 and are loaded to run. This is warmly shown by the northwestern heat wave at the end of June and the beginning of July 2021. Recent bite analysis shows that it was one of 150,000 years of climate-free events. It was a 1-in-1500-year event in our current climate, making everything, but unimaginable, now a marginal event. If the world manages to somehow keep heating on the threshold of the Paris Agreement of 2 degrees Celsius (3.6 degrees Fahrenheit), the event will probably happen every five to 10 years. It is thoughtful to think.

“Climate change is causing us to break our heat records, and this is going to be some colder summers of the 21st century if we don’t act on the climate,” Dello said.

We urgently need to adjust to life with the heat

Given the risks that have taken place in the Northwest and elsewhere, from the unprecedented fires in Australia and Siberia last year to the warming of sea ice that has eroded in the Arctic, it is clear that work is ready for us. First and foremost, reducing emissions is vital.

But it also adapts to heat waves. A few success stories need to be looked at, although they all arose after the tragedies. 2003. heat wave killed about 70,000 in Europe. Governments responded with easier-to-use warning systems and other heating plans, and in the following years, even worse heat waves left fewer dead.

The Northwest still counts the dead, but it is becoming increasingly clear that many were poor, old, and / or alone when they died. More refrigeration centers or programs that subsidize air conditioning for those who are helped are one way to help. Low-income households, especially black, Latin American and indigenous, spend four times as much on utilities as their wealthier counterparts. It is clear that the terrain must be leveled. Social programs can also play a role. New York recently implemented a pilot program to “promote community cohesion” by ensuring that those tied to someone’s house inspect them during extreme heat. Mutual assistance groups as well played a key role in response to Pacific northwest heat.

But repairs at the individual level are not enough. Our cities need a thorough heat overhaul. This includes more green space to combat the heat island, especially in poorer neighborhoods and color communities. Reduced communities, for example, to face the extreme heat. Given the energy load that black and brown communities endure along with extreme heat, it is more vital than ever that any plan to keep people cool is just one.





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