How is "crosswind" defined in aviation?

In aviation, "crosswind" is specifically defined as wind that blows perpendicular to the runway direction. This creates challenges during takeoff and landing because it can push an aircraft off its desired flight path.

When attempting to operate an aircraft during crosswind conditions, pilots must apply correct techniques to maintain control and ensure safe operations. For instance, during takeoff or landing, a pilot may need to angle the aircraft slightly into the wind to counteract the lateral push and maintain a straight path down the runway. Understanding the dynamics of crosswinds is crucial for pilots, as strong crosswinds can significantly affect flight safety and technique.

While other options describe different types of wind conditions, only the definition of crosswind captures the essence of how wind interacts perpendicularly with the aircraft's flight path.