US is measuring extreme heat incorrectly

late In the 1970s, a physicist and textile engineer in Texas named Robert Steadman published a paper titled “”.estimation of humidityAn unpleasant kind of steam appears in the title—how temperature and humidity combine to make life difficult on the body. To do so, he drew on a long history of experimentation. In the 18th century, people 250 degrees Fahrenheit, to see how long they could suffer as they watched steaks cook next to them. In the 19th and early 20th centuries, researchers observed people in Turkish bathhouses. sweat and report from mines where they measured ambient conditions as workers collapsed from heat exhaustion. Later, the military conducted more tests, measuring blood flow, sweating, and breathing as response to atmospheric extremes. got the equations for .

What was unique to Steadman was his intimate knowledge of clothing; He was known for projects such as a universal sizing system for garments, and motors that spin fine cotton yarn. After all, he theorized, people are rarely naked in the heat, so our perception of it must be mediated by a combination of physiology and clothing. Their formulas considered the exact percentage of how much skin would be covered by the fabric, and how specific mixtures of fibers and fibers would transfer heat from the air.

Surprisingly, Steadman’s measurement of humidity proved useful to weather forecasters, especially in the United States, thanks to a set of calculations developed by a textile researcher. In 1990, a scientist from the National Weather Service found him with Steadman’s key features more or less intact. Since then, the humidity index has come to be known more (or perhaps less) as the “heat index”, although it is also sometimes referred to as “apparent temperature” or “actual experience”. if you are caught this heat waves, this is probably the number one you have consulted to better understand the torturous situation outside. It is the measure that is supposed to incorporate an overlooked factor in the human experience with heat: humidity. That wetness in the air slows the evaporation of sweat from your skin—an important way to stay cool.

What made Steadman’s index successful was that the numbers felt Right, literally. The heat index reads like temperature, but it is even more volatile than that, an assumption rooted in physical reality. When two different combinations of heat and humidity result in the same heat index — say, 96 degrees Fahrenheit / 50 percent humidity and 86 degrees / 95 percent humidity, both of which have a heat index of 108 — this means That each scenario in the body is at the same level of tension as it tries to calm down. As the temperature index rises, the miracle of internal thermoregulation that stabilizes our bodies at 98.6 degrees Fahrenheit begins to crumble. our core temperature rises, which starts off as unpleasant And then it becomes dangerous, There is about a 10 degree window before all the chemistry that sustains life fails. ie death,

But there’s a problem with Steadman’s calculations: They weren’t really built to handle those kinds of extreme situations. At a certain range—which includes a steamy combination of 80 percent humidity and 88 degrees Fahrenheit—the heat index predicts what David Romes, a physicist and climate scientist at the University of California, Berkeley, calls “material conditions.” Rarely occurs in the lower parts of the atmosphere. This involves contact with the skin creating supersaturated air – that is, air that is more than 100 percent saturated with water.

Temperature and humidity conditions beyond that range are somewhat rare—and when they do occur, it is possible to extrapolate from Steadman’s model to come up with an estimated heat index value. But estimates are guesswork, and such heat waves are becoming more common as temperatures rise. So Romps and his graduate student, Yi-Chuan Lu, Getting started with a look at the fundamentals of the model, He quickly realized that, thanks to the long list of assumptions in the equations, some things were missing. For one thing, oversaturation is a natural solution to the problem: When the air is too wet for human sweat to evaporate, it can still bead and drip from the skin, providing some relief.

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