# Surface speed of atmosphere and jet fuel

1. Oct 6, 2016

### Sawdust7

The surface of the earth is moving approx. 1000 miles per hour at the equator. Which means, excluding natural wind and especially hurricanes, the air is also moving about 1000 miles per hour along with the surface, or the central areas of the earth would be stripped of just about everything…trees, mountains, water, etc. The poles would get real crowded : >)

The earth rotates west to east. Which means all the air is also moving west to east at about 1000mph.

If a plane flies 400mph from Calif. to NY and then NY to Calif, does it take more fuel to fly from NY to Calif. against the 1000 mph air? Even just a little bit?

2. Oct 7, 2016

### Staff: Mentor

And the plane parked on the ground is moving 1000 mph.

One needs to look at ground speed and wind speed, which is relevant, not the speed of the surface of the earth. There are two important effects, the wind velocity with respect to the earth's surface, and the actual speed of the aircraft. If the wind generally flows from west to east, a plane will use less fuel for the same ground speed when moving with the wind as opposed to moving against the wind. Secondly, as a plane flies with a ground velocity to the east, it effectively weighs less due to centripetal force, so it requires less lift. A plane flying west effectively weighs more, so requires more lift, which takes more energy. So in general, a plane uses more fuel per mile flying west than it does when flying east.