The blustery winds over the past month have made us feel as if winter has set in for real. It is Hawaii, and the temperature rarely drops into the 60s, but we have “thin” blood and feel the cold more than our temperate-climate counterparts who might welcome 70 degrees in February as a cause for celebration.

Temperature control of the body is a complex physiological process called homeostasis. All mammals are warmblooded and need to keep a nearly constant body temperature. The body does this by balancing heat gain against heat loss.

Metabolism produces heat from controlled oxidation of glucose and other chemicals produced from digestion of food and controlled by the liver. When we are cold or in motion, the body produces more heat. Without heat loss, heat would build up, body temperature would rise and we (the organism) would literally burn up.

Heat loss comes from three sensible methods, and a fourth from evaporation. The sensible methods are conduction, convection and radiation.

In cold air, evaporation is less of a factor than in warm air because cold air cannot contain as much water vapor as warm air. Evaporation is responsible for the chill we feel in our cool winter winds.

Conduction is least important for heat loss. In still air, which is a poor conductor, a millimeter-thin layer next to the skin helps to insulate from heat loss. This reduces evaporation and makes us feel muggy when the humidity is high. A fan moves air to help us feel cooler when the air is otherwise still.

The boundary layer is thickest and provides maximum insulation when the wind is less than 0.5 mile per hour. As the wind speed increases, the boundary layer gradually thins up to wind speeds of about 35 mph. Above that the boundary layer is gone, and increased wind speed has less effect on heat loss.

All objects — people and animals included — radiate heat that is proportional to temperature. Infrared images can show the radiated heat, from various exposed parts of the body.

The wind chill equivalent temperature, or WET, is the temperature at which exposed skin loses heat at the same rate as if there were no wind. Above 40 degrees the wind chill factor is only a degree or so different from the actual temperature but can still cause hypothermia.

At 40 degrees, with a wind speed of only 5 miles per hour, the WET drops to 36 degrees. This means that the wind causes the body to lose heat at the same rate as it would if exposed to a temperature of 36 degrees with no wind.

Frostbite cannot occur if the air temperature is above freezing regardless of the wind speed and does not become a serious threat until the temperature drops below 10 degrees or so.

Even though wind chill is not a factor in our subtropical climate, we still feel cold when the wind blows. Blame it on evaporation and not wind chill.

Richard Brill is a professor of science at Honolulu Community College. His column runs of the first and third Fridays of the month. Email questions and comments to brill@hawaii.edu.