During the winter months many decisions are made that depend upon air temperatures and the extremes which might be expected. We choose our dress and plan our activities according to the thermometer. If we have to be outdoors, as is the case with students or commuters who have to stand waiting for a bus, we know that the temperature alone gives too little information for good decision-making. If the temperature is zero with a light wind, we would not be as cold as with a strong wind.
Wind chill causes the air to feel colder than it really is.
The human body is constantly radiating heat. This picture is an infrared photo showing the heat radiated from a person holding a burning match. When air is still the heat radiating away from a person stays nearby and serves to warm the air. So people don't lose their heat as fast when the air surrounding them is still. When wind velocities are near zero and you are standing still, your body heat warms the air near your body.