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Why fur-lined hoods are so warm: The science and history

With Chicago-area temperatures in the single digits or teens through the first week of the new year, every effort to preserve warmth counts. Much has been written about the long, black puffy coat and anything made by Canada Goose, but what of the fur-lined hood -- is it warmer than a traditional hood?

Turns out history and science have an answer. And it's yes.

A 2004 study took traditional caribou-skin jackets with huge fur-lined hoods worn by Inuit people and tested them in a wind tunnel vs. contemporary jackets with and without fur on the hood. The fur-lining made a huge difference. "The superior effectiveness of this piece of clothing has been known by Inuit hunters and seamstresses, who have thrived for thousands of years by creating polar ruff designs that provide protection against the cold, windy arctic climates," the paper from researchers at the universities of Michigan, Washington and Manitoba concluded.

To see how the science works, click the button.

Hood with no fur

Thinner

boundary

layer

1

COLD WIND

REGULAR

HOOD

More

loss of

heat from

head

2

Thinner

boundary

layer

1

REGULAR

HOOD

COLD

WIND

More loss of

heat from head

2

Fur-lined hood

Thicker

boundary

layer

1

1

COLD WIND

FUR-LINED

HOOD

Much

less

loss of

heat from

head

2

Thicker

boundary

layer

1

1

FUR-LINED

HOOD

COLD

WIND

Much less loss

of heat from head

2

Boundary layer

Without fur: Where blowing wind contacts the hood, friction from a collision of molecules creates a thin layer of air called a boundary layer. The thickness of the layer is proportional to the diameter of the hood. It acts as an insulation layer. A thinner layer means less insulation.

With fur: The larger fur liner creates a larger boundary layer. In addition, the fur (with different hair lengths) changes the dynamics of how the cold air flows by for different wind directions, an effect which increases the boundary layer even more.

Heat transfer

Without fur: The body gives off heat, including from your face. When wind blows by, facial heat is transfered or carried away, making your face and you colder.

With fur A hood without fur does decrease heat transfer, but only slightly. Hoods with fur decrease the amount of heat lost, thus keeping your face and you warmer. The larger the diameter, variety of fur, and if the fur is natural, the warmer your face will be. Synthetic fur sometimes is uniform in length, and not as effective as natural. A typical modern jacket sporting a hood with an inch of fur will keep you warmer, but not as warm as a real-fur lining would.

A selection of fur-lined hoods

Inuit sunburst parka: The hood is typically made from caribou or seal skin with fur from an arctic fox, wolf, dog or wolverine. The irregular length hairs from these animals disrupt the wind, creating a calm boundary around the face.

1950s-70s military parka: This precursor to the modern parkas was made of nylon or polyester, designed for extremely cold areas. Some versions were made with real fur and some with synthetic.

Modern parka: Usually a nylon shell hood filled with down insulation. Many types have synthetic fur trim or, if real, fur from a coyote or fox.

Read the full paper, "Effect of ancient Inuit fur parka ruffs on facial heat transfer"

Photos: Sunburst from Getty images, military from U.S. Air Force, modern from Chicago Tribune

Sources: "Effect of ancient Inuit fur parka ruffs on facial heat transfer," by Aline J. Cotel, University of Michigan; Raymond Golingo, University of Washington, and Jill E. Oakes and Rick R. Riewe of the University of Manitoba; NASA; Encyclopaedia Britannica

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