Weathervaning or weathercocking is a phenomenon experienced by aircraft on the ground.

Aircraft on the ground have a natural pivoting point on an axis through the main landing gear

Undercarriage

The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...

 contact points [disregarding the effects of toe in/toe out of the main gear]. As most of the side area of an aircraft will typically be behind this pivoting point, any crosswind

Crosswind

A crosswind is any wind that has a perpendicular component to the line or direction of travel. In aviation, a crosswind is the component of wind that is blowing across the runway making landings and take-offs more difficult than if the wind were blowing straight down the runway...

 will create a yawing moment

Stability derivatives

Stability Derivatives, and also Control Derivatives, are measures of how particular forces and moments on an aircraft change as other parameters related to stability change . For a defined "trim" flight condition, changes and oscillations occur in these parameters...

 tending to turn the nose of the aircraft into the wind.

It is not to be confused with directional stability

Flight dynamics

Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...

, as experienced by aircraft in flight.