# Why does air move with the planet Earth **URL:** \ **Category:** Factual Questions\ **Created:** [November 12, 2021, 11:54pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260 "2021-11-12T23:54:22Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [November 12, 2021, 11:54pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/1 "2021-11-12T23:54:22Z")
I was listening to a podcast about the geocentric model of the solar system vs heliocentrism. Apparently a “proof” at the time that the earth was not spinning was that if you tossed a ball into the air, it would land right back where it started (assuming a perfectly vertical toss). If the earth was spinning, the logic goes, it would land a good bit away. The answer of course was that the earth _and the air that surrounds it_ is moving. That’s all easy enough to understand in this day and age but it got me thinking… Why does the surrounding gas (air) move so in sync with the solid (earth)? It doesn’t seem like there is anything to really to drag the air along with the planet except a tiny amount of friction. If you toss a ball up in a plane, for example, it follows the path of the plane because the air is trapped between walls. But the air over the earth has no such containment, the surface of the earth has no boundary. It seems like there should be some slippage. What am I missing? ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [November 12, 2021, 11:59pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/2 "2021-11-12T23:59:23Z")
Gravity? It pulls on all things, including the atmosperic gases. The Earth is a very large mass compared to a basketball. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [November 13, 2021, 12:07am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/3 "2021-11-13T00:07:09Z")
> [@Lucas\_Jackson](#): > > Apparently a “proof” at the time that the earth was not spinning was that if you tossed a ball into the air, it would land right back where it started (assuming a perfectly vertical toss). If the earth was spinning, the logic goes, it would land a good bit away. The answer of course was that the earth _and the air that surrounds it_ is moving. Actually that’s wrong - the ball is _already_ moving with the earth when it is in your hand. Tossing it straight up doesn’t change that, there’s no reason why it should suddenly move backwards when it leaves your hand. Air has nothing to do with it, that would happen in a vacuum too. To the original question, it is gravity **and** friction together doing this. But not completely; weather generally moves from the west to east because the earth is revolving east to west under the atmosphere, which is only partially dragged along with it. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [November 13, 2021, 12:08am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/4 "2021-11-13T00:08:31Z")
Not sure why that would be the answer. If I set a basketball on the back of a flatbed truck and accelerate, the ball will not follow along even though it is being acted on by gravity. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [November 13, 2021, 12:11am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/5 "2021-11-13T00:11:52Z")
> [@Askance](#): > > Actually that’s wrong - the ball is _already_ moving with the earth when it is in your hand. It probably is wrong but that is what was claimed as a proof in Nicolaus Copernicus’ time. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [November 13, 2021, 12:13am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/6 "2021-11-13T00:13:34Z")
> [@Lucas\_Jackson](#): > > Not sure why that would be the answer. If I set a basketball on the back of a flatbed truck and accelerate, the ball will not follow along even though it is being acted on by gravity. As I said, friction **and** gravity. You’ve removed one of those ingredients there. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [November 13, 2021, 12:36am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/7 "2021-11-13T00:36:11Z")
> [@Lucas\_Jackson](#): > > It seems like there should be some slippage. There is slippage. The Coriolis force is apparent via this slippage, and from there the weather systems. So the slippage is manifested as the cyclonic form of high and low pressure systems, and from there the direction of winds. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [November 13, 2021, 12:36am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/8 "2021-11-13T00:36:46Z")
> [@Askance](#): > > As I said, friction **and** gravity. You’ve removed one of those ingredients there. I was responding to Si\_Amigo. You slipped in between. 😉 ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [November 13, 2021, 12:41am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/9 "2021-11-13T00:41:30Z")
> [@Askance](#): > > To the original question, it is gravity **and** friction together doing this. But not completely; weather generally moves from the west to east because the earth is revolving east to west under the atmosphere, which is only partially dragged along with it. Actually the earth revolves the other way, west to east (counterclockwise as seen from above the North Pole). The prevailing winds are in opposite directions in most of the northern vs southern hemisphere. The direction of prevailing winds is a complex mix of prevailing pressure differentials at different latitudes plus Coriolis forces as already mentioned, and look like this: > **[Prevailing winds](https://en.wikipedia.org/wiki/Prevailing_winds)** > > In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point on the Earth's surface at any given time. A region's prevailing and dominant winds are the result of global patterns of movement in the Earth's atmosphere. In general, winds are predominantly easterly at low latitudes globally. In the mid-latitudes, wester Wi... ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [November 13, 2021, 12:41am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/10 "2021-11-13T00:41:45Z")
> [@Lucas\_Jackson](#): > > Not sure why that would be the answer. If I set a basketball on the back of a flatbed truck and accelerate, the ball will not follow along even though it is being acted on by gravity. Once you introduce acceleration you are solving a whole different problem. ---
**Author:** ![AlsoNamedBort](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alsonamedbort/32/3213_2.png) [@AlsoNamedBort](https://boards.straightdope.com/u/AlsoNamedBort)\ **Post date:** [November 13, 2021, 2:19am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/11 "2021-11-13T02:19:48Z")
> [@CookingWithGas](#): > > Once you introduce acceleration you are solving a whole different problem. Yes, the Earth does not accelerate. If it suddenly did for some reason, we would lose a lot of the atmosphere. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [November 13, 2021, 2:24am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/12 "2021-11-13T02:24:18Z")
> [@AlsoNamedBort](#): > > we would lose a lot of the atmosphere. Or a lot of us, depending on the sudden differential speed between the atmosphere and the surface. ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [November 13, 2021, 8:37am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/13 "2021-11-13T08:37:50Z")
> [@CookingWithGas](#): > > Once you introduce acceleration you are solving a whole different problem. Indeed, and even then the friction induced by gravity may be enough to allow very, very, very gradual acceleration without the ball rolling backwards. And of course once you reach a steady velocity it’ll sit there quite happily. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [November 13, 2021, 10:55am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/14 "2021-11-13T10:55:05Z")
I actually tried the ball-tossing experiment as a young-un. I was disappointed to find that the ball dropped neatly back into my hand. A slightly older, slightly wiser me decided that the earth’s movement would have been too subtle to demonstrate any effect of 10-year-old Mean Kid Mustard tossing a rubber ball five feet in the air. That still seems plausible to me. Is it correct? mmm ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [November 13, 2021, 11:25am UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/15 "2021-11-13T11:25:06Z")
> [@Mean\_Mr.Mustard](#): > > A slightly older, slightly wiser me decided that the earth’s movement would have been too subtle to demonstrate any effect of 10-year-old Mean Kid Mustard tossing a rubber ball five feet in the air. > > That still seems plausible to me. Is it correct? Yes. The Earth’s surface _is_ accelerating, constantly in a circle, but you need more patience and something more sensitive than your hand and a ball. Like this: > **[Foucault pendulum](https://en.wikipedia.org/wiki/Foucault_pendulum)** > > The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist Léon Foucault, conceived as an experiment to demonstrate the Earth's rotation. A long and heavy pendulum suspended from the high roof above a circular area was monitored over an extended time period, showing that its plane of oscillation rotated. > The pendulum was introduced in 1851 and was the first experiment to give simple, direct evidence of the Earth's rotation. Foucault followed up in 1852 with a gy... ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [November 13, 2021, 1:10pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/16 "2021-11-13T13:10:08Z")
> [@Askance](#): > > As I said, friction **and** gravity. You’ve removed one of those ingredients there. Actually, the critical word in **L\_J** ’s thesis is “accelerate.” The basketball, stationary truck, and Earth are all moving at the same speed and direction. When the truck changes in relation to the Earth by driving away, the basketball gets left behind – less the effects of friction. Edit: Ninja’d (11 hours ago) by **CWG**. ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [November 13, 2021, 1:36pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/17 "2021-11-13T13:36:36Z")
> [@Ponderoid](#): > > {…} The Earth’s surface _is_ accelerating, constantly in a circle, {…} Umm, isn’t the Earth moving at a constant velocity, not accelerating? Just want thank the OP, this thread is giving me major flashbacks to all the time I’ve heard this all explained to YouTube flat Earthers! ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 13, 2021, 1:46pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/18 "2021-11-13T13:46:03Z")
Of course the friction is tiny, but so what? That just means that it would take a long time for the air to (mostly) come to rest with respect to the surface… Maybe as long as a day or so? But it’s had four billion years. Even with only a very tiny amount of friction, that’s plenty. ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [November 13, 2021, 1:47pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/19 "2021-11-13T13:47:01Z")
Gravity affects air, too, but there are other things going on with weather, such as the surface of the Earth heating because of the sun, exciting air particles, plus changes in humidity, etc. Felix was still subject to gravity at 128K feet, though. You have to escape gravity to let the Earth spin below you without pulling you along. [![](https://img.youtube.com/vi/FHtvDA0W34I/maxresdefault.jpg "Felix Baumgartner's supersonic freefall from 128k' - Mission Highlights") ](https://www.youtube.com/watch?v=FHtvDA0W34I) ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [November 13, 2021, 1:48pm UTC](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260/20 "2021-11-13T13:48:02Z")
But the fact you are moving in a circle _is_ acceleration, from a physicist’s point of view. The acceleration is what makes the Foucault pendulums alluded to above change their direction over time. [Next page](https://boards.straightdope.com/t/why-does-air-move-with-the-planet-earth/954260.md?page=2)