What is the reason for the warming of the cold air inhaled through the nose?

Air that is inhaled through the nose initially enters the nasal cavity. The latter has a tortuous and at the same time mucous surface. The sinuous surface provides a large surface area in the narrow nasal cavity. The large surface area, in turn, contributes to a large accumulation of blood vessels here. And this creates conditions for the flow of the maximum amount of blood. This is the main factor that warms the cold inhaled air.