headwind

A headwind is wind that blows directly against the direction of travel of an object, increasing the relative airspeed experienced by the traveler and raising aerodynamic drag. It reduces ground speed for a given airspeed and can require more energy to maintain pace. A wind blowing from a different angle is described as a crosswind (from the side) or a tailwind (from behind).

In meteorology, headwind describes the component of the wind that opposes motion along a given track. The observer also experiences apparent wind, which is the combination of true wind and the motion of the observer; headwinds contribute to higher apparent wind from the front.

In aviation, headwinds affect takeoff and landing performance, flight planning, and fuel efficiency. For a fixed indicated airspeed, a headwind lowers ground speed, which can shorten required runway length for takeoff and landing but may increase thrust and fuel use in certain phases of flight. Pilots monitor wind shear, gusts, and attitude adjustments to cope with headwinds and related turbulence.

In cycling, headwinds raise aerodynamic drag and metabolic cost, slowing progress and increasing effort. Cyclists often use drafting to reduce the impact of a headwind and may alter pacing or routing to minimize exposure to strong headwinds.

In sailing, a headwind makes progress difficult and requires tacking or sailing at angles to the wind. Boats rely on hull speed, sail trim, and course changes to optimize speed when the wind blows from the front.

Headwinds vary with weather, altitude, and geography, and planning often uses wind forecasts to anticipate their effect on travel time and energy use.