Final answer:
Windchill refers to the perceived drop in temperature caused by wind increasing the rate of heat loss from the body through convection and conduction, making the environment feel colder than the actual air temperature. A strong enough wind can considerably increase the chilling effect, making it feel much colder than it actually is.
Step-by-step explanation:
Windchill is the lowering of body temperature due to the passing-flow of lower-temperature air. It makes you feel colder than the actual air temperature because the movement of air increases the rate of cooling on the skin, similar to how a fan makes you feel cooler by increasing the rate of heat transfer during summer. When wind speed increases, it removes thermal energy from the body more quickly through the combined effects of convection and conduction.
For example, a wind speed of 15.0 m/s at 0°C can feel like still air at around -18°C because of the wind-chill factor. The phenomenon of windchill provides a stark reminder of the fact that air, while being a poor conductor, can transfer heat rapidly by convection, significantly affecting how we perceive temperature.
Humans perceive temperature differently based on how quickly objects transfer heat away from the body, explaining why touching metal feels colder than wood at the same temperature. With insulation such as fur, feathers, or home insulating materials, the air trapped in spaces too small for convection to occur helps to maintain warmth by utilizing air's low conductivity.