Sue Ann Rosner, age 11, of Grand Forks, N.D., for her question:

CAN YOU EXPLAIN WIND CHILL TEMPERATURE?

Wind chill is an estimate of how cold the wind makes a person feel in cold weather. The faster the wind blows, the faster the body loses heat. Therefore, the feeling of cold increases as the speed of the wind increases.

As an example of this, when the temperature is 10 degrees Fahrenheit and the wind is blowing at a speed of 10 miles per hour, the wind chill temperature is equal to minus nine degrees Fahrenheit. This means that with a 10 miles per hour wind at 10 degrees Fahrenheit, people lose as much heat and feel as cold as they do when the temperature is minus nine degrees Fahrenheit and the wind is calm.

Wind chill is not an exact measurement of cold because temperature and wind are not the only conditions that make people feel cold. Someone who is thin or whose clothes are damp will lose more heat and feel colder than another person.

But the wind chill temperatures can give a better idea of how cold it feels than a temperature reading alone.

Wind chill measurements were developed from experiments performed in Antarctica in 1939.