Final answer:
Surface wind can vary significantly from the gradient wind, affecting a plane's total velocity and requiring pilots to adjust the approach angle. Pilots must calculate a vector equation to account for wind effects during instrument approaches.
Step-by-step explanation:
The surface wind can vary from the gradient wind due to the presence of friction at the Earth's surface which causes the wind to slow down and change direction. This change in wind speed and direction can be significant for aviation, especially during instrument approaches. Pilots must be aware of these variations to safely land the aircraft. When the wind interacts with an airplane, as explained in the provided reference, it can have a substantial impact on the plane's total velocity and the direction of travel. A plane may experience a crosswind and head-wind combination, leading to a total velocity that is considerably lower than its air mass relative velocity, ultimately requiring the pilot to adjust the approach angle to align with the runway for a safe landing.
Determining how wind varies over distance, as meteorologists do for tornado predictions, involves vector calculus and understanding the effects of atmospheric pressure and temperature changes on wind behavior. It's essential for a pilot to construct a vector equation to solve for the plane's velocity relative to the ground, taking into account the wind's effects. During an approach, the pilot might need to execute last-minute maneuvers to correct for wind drift and ensure the landing gear is correctly aligned with the runway.