It was the coldest day on record in Indiana, with temperatures reaching 25 degrees below zero Fahrenheit.
The Weather Service, using the existing wind-chill formula, determined that with winds of about 15 miles per hour, the air temperature could feel as if it were 65 degrees below zero — capable of causing frostbite within 15 seconds. Stay indoors, the service advised.
But as he shoveled away, Dr. Bluestein found that it really did not feel all that cold.
“He kept taking off layers of clothing,” Karen Bluestein said in a telephone interview. “He was sweating, thinking: ‘This makes no sense. I wonder who came up with this.’”
Dr. Bluestein had always been interested in how engineering could be applied to meet personal human needs. He worked on the Apollo space program to help create spacesuits that addressed waste management for NASA’s first moon landing. He worked for the Veterans Administration on designs for artificial limbs, and for Litton Medical Systems in its development of ultrasound imaging for detecting breast cancer.
This time, he set out to improve what he deemed an inaccurate, and alarmist, measurement for wind chill.
“The old system scared people into taking unnecessary actions,” Dr. Bluestein told The Wausau Daily Herald in Wisconsin 2001. “There are schools, for instance, that close at certain wind-chill temperatures when perhaps they shouldn’t be closed.”
The two scientists who developed the original system, Paul Siple and Charles Passel, based their research in the 1940s on a simple experiment: They hung water bottles from a pole on the roof of their research building and measured how quickly the water lost heat (or how quickly the water turned to ice). At the same time, they measured the surrounding air temperature and wind speed.
They found that the higher the wind speed, the faster the water froze. For people, that meant the windier it was, the faster they lost heat and the colder they felt.
Dr. Bluestein found numerous flaws with the experiment. The researchers had assumed that the temperature of human skin was 90 degrees Fahrenheit (it was closer to 50 degrees on a really cold day); they had placed the containers 33 feet above the ground, where wind speeds are higher (rather than the height of a person); and they took their measurements where it is far colder than where most people…