Which factor is not included among the three factors that determine air density?

Air density is influenced by several atmospheric factors, of which temperature, humidity, and altitude are the primary contributors.

Temperature affects air density because warmer air tends to be less dense since the molecules have more energy and are more spread out. In contrast, cooler air is denser as the molecules are more closely packed together.

Humidity also plays a role because water vapor is less dense than the nitrogen and oxygen it replaces in the atmosphere. When humidity increases, the air's density decreases.

Altitude is significant because as altitude increases, atmospheric pressure decreases. Since air pressure is directly related to air density, higher altitudes result in lower air density.

Wind speed, however, does not have a direct effect on air density. Instead, it influences the movement of air and can affect weather patterns, but it does not change the fundamental properties of air that determine its density. Therefore, wind speed is the correct answer as it is not one of the three primary factors that determine air density.