Define wind shear and explain why it is critical during takeoff and landing.

• A. A rapid change in wind speed or direction with altitude; can cause sudden loss/gain of airspeed and control issues during approach/departure.
• B. A gradual increase in wind speed with altitude; improves lift.
• C. A change in humidity with altitude; affects visibility.
• D. A static wind condition with no variation.

Answer: (A)