✔ 最佳答案
According to General Relativity(廣義相對論), gavity affects the progress of time. Time appears to go slower under strong gravitation. This is the "time dilation" effect.
Because the gravity at earth surface is stronger than that at mid-air (high altitude), time should progress at a slower pace at earth surface as compared with that at high altitude.
However, given the extremely small difference in gavitational force between earth surface and mid-air, the difference in time is hardly observable. But such difference would become prominent under situation of a very strong gravitational gradient, e.g. close to a black hole or neutron star.