Why do Aeroplanes need to go so high to travel?

Question

I hope I convey my point probably, but why do planes go so many thousands of feet in the air? Is it faster that way, or could they achieve similar flight times at a lower altitude?
Does it have something to do with the curvature of the earth?

In: Engineering

Answer 1

Planes travel faster the higher they go. Which in turn means less fuel consumption. Which in turn means less expenses.