Crosswind

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A crosswind is any wind that is blowing perpendicular to a line of travel, or perpendicular to a direction. In aviation, a crosswind is the component of wind that is blowing across the runway making a landing more difficult than if the wind were blowing straight down the runway. If a crosswind is strong enough it may exceed an aircraft's crosswind limit and an attempt to land under such conditions could cause structural damage to the aircraft's undercarriage.

Crosswind is sometimes abbreviated X/WIND.

Crosswinds can also occur when traveling on roads, especially on large bridges and highways, which can be dangerous for motorists because of possible lift force created as well as causing the vehicle to change direction of travel. The safest way for motorists to deal with crosswinds is by reducing their speed to reduce the effect of the lift force and to steer into the direction of the crosswind.

When winds are neither perpendicular nor parallel to the line of travel, the wind is said to have a crosswind component; that is it can be separated into two components, a crosswind component and a headwind or tailwind component. A vehicle behaves as though it is directly experiencing a crosswind in the magnitude of the crosswind component only.

The crosswind component is computed by multiplying the wind speed by the sine of the angle between the wind and the direction of travel. For example, a 10-knot wind coming at 45 degrees from either side will have a crosswind component of 10 kts•sin(45°) or approximately 7.07 knots. The headwind component is computed in the same manner, using cosine instead of sine. To determine the crosswind component in real world flight aviators frequently refer to a chart on which the wind speed and angle are plotted and the crosswind component is read from a reference line.