Final answer:
The ground speed at touchdown will be higher at a high-altitude airport compared to sea level due to lower air density. This necessitates a higher speed for the same lift, explaining why it's better for airplanes to take off into the wind for immediate lift.
Step-by-step explanation:
When approaching to land at a high-altitude airport, the ground speed at touchdown will be higher than it would approaching an airport at sea level given the same temperature and wind conditions. This is because the air density is lower at high altitudes, reducing the drag on the aircraft, thus requiring a higher speed to generate the same amount of lift necessary for a safe landing. Additionally, when airplanes take off into the wind, they achieve lift sooner because the relative wind speed over the wings is increased, which is why it's preferable to take off into the wind rather than with it.