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Date: July 29, 2021 08:04AM
Longtime Jacksonville WJXT meteorologist George Winterling developed the heat index.
https://www.washingtonpost.com/blogs/capital-weather/-gang/post/the-origins-of-the-heat-index-and-why-its-important/2011/07/21/gIQASKrnRI_blog.htmlJacksonsville, Fla. broadcast meteorologist George Winterling, published a revised and adapted version of the humiture in the late 1970s in the Bulletion of the American Meteorological Society and began reporting it on-air.
Based on the work of Robert Steadman, who published several seminal studies on the “assessment of sultriness,” the National Weather Service (NWS) then made operational what became the heat index.
Heat is the top weather related killer in the U.S. But there’s truth in the saying, “It’s not the heat, it’s the humidity.” The body cools itself at a slower rate when the humidity is high. For this reason, the heat index was devised, to provide a measure of how hot it actually feels - hence alternative names such as “apparent temperature,” “feels like temperature,” “real-feel temperature”(AccuWeather trademark), “humiture,” and in Canada, “humidex.”
Perhaps originating from some commentary by radio host Rush Limbaugh, questions have arisen as to whether the heat index is a legitimate scientific measure. I can assure you it is. Moreover, it’s critical for communicating health risks related to the potentially deadly combination of heat and humidity.
The roots of the heat index can be traced to Osborn Fort Hevener (described by the New Yorker as a New Jersey weather buff), who coined the term humiture in the early 1900s. In a 1959 issue of Weatherwise magazine, Hevener wrote:
Twenty-two years ago, I was fortunate to coin two words that have found their way into the dictionaries, and to develop a concept that has proven useful and popular. To let the secret out, I am the humiture man.
In the 1957 Thondike-Barnhart dictionary, humiture was defined as ”a combined measurement of temperature and humidity, arrived at by adding degrees of temperature to percentage of relative humidity and dividing by two.”
But this simplistic definition would evolve.
Jacksonsville, Fla. broadcast meteorologist George Winterling, published a revised and adapted version of the humiture in the late 1970s in the Bulletion of the American Meteorological Society and began reporting it on-air.
Based on the work of Robert Steadman, who published several seminal studies on the “assessment of sultriness,” the National Weather Service (NWS) then made operational what became the heat index
The heat index results from a whole research area on weather and its effects on the human body, known as biometeorology. The index is grounded in established relationships describing the exchange of heat and moisture between the human body and the atmosphere.
Consider all the following quantities factored into determining heat index: vapor pressure, dimensions of a human, effective radiation area of skin, significant diameter of a human, clothing cover, core temperature, core vapor pressure, surface temperatures and vapor pressure of skin and clothing, activity, effective wind speed, clothing resistance to heat transfer, clothing resistance to moisture transfer, radiation from the surface of the skin, convection from the surface of the skin, sweating rate, ventilation rate, skin resistance to heat transfer, skin resistance to moisture transfer and surface resistance to moisture transfer.
For practical purposes, all of these quantities can be condensed into an simplified equation for calculating heat index requiring just temperature, relative humidity, and a number of constants.
https://www.washingtonpost.com/weather/2021/07/24/wet-bulb-temperature-extreme-heat/As the air around you gets more humid, your body is less able to sweat effectively, meaning you can’t cool off as successfully. That’s why dry heat feels more tolerable than extreme humidity.
“If the wet-bulb temperature reading is higher than our body temperature, that means that we cannot cool ourselves to a temperature tolerable for humans by evaporating sweat, and that basically means you can’t survive,” said Tapio Schneider, a California Institute of Technology climate scientist and professor.
The term wet bulb comes from a way the measurement can be taken, by wrapping a piece of wet cloth around the end of a thermometer to see how much evaporation can decrease the temperature.
“The idea here is that you and I are essentially wet bulbs,” Schneider said. “We cool ourselves by evaporation.”
Edited 1 time(s). Last edit at 07/29/2021 08:11AM by anybody.