# B Our atmosphere and the rotating Earth

1. Feb 20, 2017

### pkt

What force keeps our atmosphere spinning with the rotating earth? How can there ever be a calm day?

2. Feb 20, 2017

### Comeback City

I would think of it this way...
Earth's magnetic field protects it from Solar winds.
Earth's gravity holds it in.

3. Feb 20, 2017

### pkt

But what force syncs the sky with the rotating earth enough to have puffy white motionless clouds when we are spinning at up to 1000 mph?

4. Feb 20, 2017

### Staff: Mentor

There is no force necessary to stay in uniform motion. The air just keeps moving in the same way you and the ground below you keep following the rotation.

5. Feb 20, 2017

### Comeback City

The clouds aren't stationary. They are constantly moving and rotating with the Earth. It's just special relativity: motion relative to something else.

6. Feb 20, 2017

### pkt

What force is making the puffy motionless cloud move at up to 1000 mph with the earth? It is not attached to the earth. There is no force makes no sense.

7. Feb 20, 2017

### Staff: Mentor

Why does no force make no sense? Do you know Newton's First Law?

8. Feb 20, 2017

### Staff: Mentor

If the atmosphere would move relative to the ground (apart from local wind), friction would quickly make it move in the same way as the ground.

9. Feb 20, 2017

### pkt

It makes no sense because most of the time those puffy white clouds are not stationary but moving eastward faster than the Earth is rotating.

10. Feb 20, 2017

### FactChecker

It has had billions of years for the atmosphere to match the solid Earth speed. In fact, it may have matched from the day the Earth formed. Once the atmosphere is spinning, it would actually take force to slow it down. That force doesn't exist, so the atmosphere and solid Earth just keep spinning together.

11. Feb 20, 2017

### FactChecker

Overall, the atmosphere and solid Earth spin at the same rate. At some latitudes, the atmosphere spins a little faster and at other latitudes it spins a little slower. But it averages out. The details are very complicated, but interesting.

PS. There is an "Earth" section under "Other Sciences" where there is a lot of discussion of things like this.

12. Feb 20, 2017

### rootone

The atmosphere is a part of Earth and the whole of Earth is rotating.
The atmosphere is not a separate thing which the Earth is spinning inside of.

The usual local wind direction where you are is exactly that.
It's a local feature, determined by local weather systems.
Elsewhere on the planet there are places where the prevailing wind direction will be opposite to where you are.

Last edited: Feb 20, 2017
13. Feb 20, 2017

### Staff: Mentor

So what? You seem to think the clouds have to fight something to move east - what do you think that is?

Again; do you know Newton's First Law?

14. Feb 20, 2017

### pkt

If you took an ant and glued his little feet to a basketball and spun it,
would he experience rotational wind in the direction of rotation?

Last edited: Feb 20, 2017
15. Feb 20, 2017

### rootone

Yes he would, because the air near the basketball isn't part of the ball, it's part of the ball's environment.
The basketball does not have an atmosphere of it's own
The case of Earth is different, the atmosphere IS itself a part of the Earth.
There isn't yet more atmosphere in space beyond the thin layer close to Earth;s surface.

16. Feb 20, 2017

### pkt

Our atmosphere can and does move against our earths rotation all the time, its not part of or attached to the earth.
Big balls in the atmosphere should act the same as small according to physics.
The ant has rotational wind in the direction of travel. Our prevailing winds are in the opposite direction.
Is there an explanation?

17. Feb 20, 2017

### rootone

As a whole the atmosphere does rotate along with the rest of Earth.
Local prevailing winds are as I said earlier, just an effect of weather systems.
Since weather systems are in the main circulating systems, other parts of Earth have different prevailing winds to those where you are,
A hurricane is the obvious example, but there are many other kinds of circulatory weather systems.

Last edited: Feb 20, 2017
18. Feb 20, 2017

### Staff: Mentor

There is just very little motion from local wind. It is connected to the Earth: wind experiences friction. You need energy input (temperature differences induced by the sun) to keep wind blowing.
Forget local wind patterns. They are not relevant to the point you misunderstand and you just confuse yourself with that irrelevant point.
No, the balls would have to have their own atmosphere. Balls thrown in the atmosphere move through the atmosphere. The Earth does not move through an atmosphere (of what?).

19. Feb 20, 2017

### pkt

If the gravity of the earth is dragging the atmosphere along with it there should be some delay, but no, those storms come rolling in from the west faster than we rotate [800 mph].

Thanks for all your help trying to understand!

20. Feb 20, 2017

### rootone

Why should there be a delay?
The oceans don't have any problem staying where they are relative to the solid Earth surface.