The team is joined by Guest Kats Rosie Burbidge, Stephen Jones, Mathilde Pavis, and Eibhlin Vardy, and by InternKats Verónica Rodríguez Arguijo, Hayleigh Bosher, Tian Lu and Cecilia Sbrolli.

Monday, 2 October 2017

In memoriam Maurice Bluestein: "Baby--it's cold outside"; the story and nomenclature of the Wind Chill Index


This post is intended for anyone who has ever been where the temperature can get below 50° F and the wind speed is greater than 3 mph (which is pretty much everyone at some time or the other). As the temperature drops and the wind increases, it feels colder outside than the temperature reading would suggest. No problem, the wind chill index will give me a degree equivalent that tells me how cold it really feels. Have you wondered where that index comes from? In fact, the wind chill index now popularly in use was the result of the work of Maurice Bluestein, a US-trained engineer and academic, and Mr. Randall Osczevsk, a Canadian environmental physicist, who jointly came up with the formula in 2001. As reported by the New York Times, Mr. Bluestein passed away several weeks in Florida at the age of 76. His story is worth retelling, both in the way that the ubiquitous wind chill index has been developed and the interesting question that it raises regarding the names of such formulaic creations.

What first needs to be appreciated is that the wind chill index formula developed by Bluestein and Osczevsk was not the first such effort. In 1945, Paul Siple and Charles Passel published the results of what is described as an “impromptu” experiment, carried out as part of their work in the United States Antarctic Expedition (1939-1941). The end product was given by Mr. Siple the name-- Wind Chill Index (WCI). As described by Bluestein and Osczevsk, "The New Wind Chill Equivalent Temperature Chart", here, Siple and Passel simply measured how long it took for water, contained in a small bottle that was “suspended from a post on the roof of the expedition building” in Antarctica, to freeze. [This Kat did something akin when, as a graduate student in Chicago, he relied on winter- long below freezing temperatures to keep meat in a basket suspended from his room by a rope tied to his window.]

Their results were then calculated in terms of a three or four-digit number, which was said to represent “the rate of heat loss of the cylinder per unit surface area.” Bluestein and Osczevsk state that the WCI became “the best-known result of a century of Antarctic research.” Nevertheless, the experimental basis for this WCI was called into question as early as 1960. Still, nothing seems to have done to materially improve the WCI until Mr. Bluestein went out one winter day in January 1994, recorded as the coldest day ever measured in the State of Indiana (25 degrees below zero Fahrenheit), to shovel his daughter’s car out of a snow drift.

The question was: how wise was Bluestein in doing so? After all, the then in effect WCI told him that it should feel like 65 degrees below zero, the kind of cold that would bring on frostbite within 15 seconds. The problem was that Mr. Bluestein did not at all feel that it was so cold. As his daughter told the New York Times, “He kept taking off layers of clothing. He was sweating, thinking: This makes no sense. I wonder who came up with this.” There was a practical side in all of this. Perhaps the index then in place led to overly-alarmist behavior, such as Mr. Bluestein himself noted, the unnecessary closing of schools.

Mr. Bluestein began to dig more deeply into the experiment carried out by Siple and Passel, focusing on the unusual circumstances in which the experiment took place (Antarctica hardly being typical of anywhere else) and various flaws in its design. He ruminated on the problem for several years until he met Osczevski, who also was working in Canada on trying to improve the WCI. [Merpel notes that WCI work seems to do better in pairs.] Several years of government-funded research and papers followed. Most notably was their experiment, summarized by the New York Times as follows:
:… [T]hey conducted a series of experiments with 12 people, male and female, measuring heat loss from the face in cold and wind as they walked on treadmills in a wind tunnel at different temperatures. A “wet trial” sprayed participants’ faces with a splash of water every 15 seconds to measure whether the presence of precipitation would make people feel colder.

After plotting the data, they found that in some cases the original wind chill index was off by just a few degrees, but that the discrepancy grew at higher wind speeds. It confirmed what many meteorologists had already suspected: The old calculation had exaggerated.” Mr. Bluestein hoped that the formula that they jointly came up with would have the result that “… people will now take it more seriously”.
This formula indeed appears to become the current basis for calculating the wind chill temperature.Besides the story of how the WCI went from experimental afterthought to rigorous experimental measurement, there is the issue of nomenclature—why don't we popularly refer to it as the Bluestein and Osczevski index? This Kat has on the shelf in his lair the book by Clifford G. Pickover, "Archimedes to Hawking: Laws of Science and the Great Minds behind Them", in which there are almost 500 pages of scientific discoveries, each identified by the name of the person whose discovery it was. Why was it that the original development by Siple and Passel was known merely as the Wind Chill Index rather than the Siple and Passel wind chill index? If this had been so, the later development by Bluestein and Osczevski would have been similarly identified. As an added advantage, the public would have been better informed that while the Wind Chill Index is a generic description, it has come in various flavors over the years in the quest to create a better and better index. As such, the various creators could have enjoyed a bit of reputation while the public would have been disabused of the notion that there is a single Platonic form of such index.

Or maybe, if the purpose of the index is to enable one to make a better decision on whether or not to brave the outdoor climes, nothing beats the blandishment approach in the She and Him lyrics of Frank Loesser's classic (and Academy Award-winning) 1944 song, "Baby—It's Cold Outside":
"I really can't stay - Baby it's cold outside

I've got to go away - Baby it's cold outside

This evening has been - Been hoping that you'd drop in

So very nice - I'll hold your hands, they're just like ice

.

.

.

There's bound to be talk tomorrow - Think of my life long sorrow

At least there will be plenty implied - If you caught pneumonia and died

I really can't stay - Get over that hold out

Ah, but it's cold outside

Oh, baby, it's cold outside

Oh, baby, it's cold outside"
For the rendition of the song in the movie, Neptune's Daughter", here.

For full lyrics of the song, here.

Picture at middle left by Lord Laitinen, who has dedicated it to the public domain.

Picture at lower right by Matthias Zirngibl and is licensed pursuant to Creative Commons Attribution 2.0 Generic.

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