# Coriolis effect questions based on this video of a tossed ball after it is released

Aeronautic Freek
Does ball (in video)when flying ,going in straight line or in curve line,so if I am inside this ball, will I feel like I am in car which accelarate in straight line or car which accelare in curve?
I think ball is going straight,curved path is just illusion..

## Answers and Replies

Science Advisor
2022 Award
In the ground frame the ball is traveling in a straight line. In the rotating frame it's traveling in a curve.

It is moving inertially, yes. It feels no acceleration once the guy has let go of it.

berkeman
Aeronautic Freek
It is moving inertially, yes. It feels no acceleration once the guy has let go of it.
So winds going in straight line so cirular motion is just illusion looking from rotating frame?

Vanadium 50 and weirdoguy
Science Advisor
2022 Award
The weather is a more complex case than the ball. The air is interacting with itself and the Earth, not just flying through empty (or nearly empty) space. Thus there are a great many interaction forces in play and the air is not moving inertially.

This is just like your three (four?) threads on centrifugal force. The ball problem can be analysed in an inertial frame or in a rotating frame. If you do it in a rotating frame you need Coriolos force to explain the curved path of the ball. If you do it in an inertial frame the ball is moving in a straight line. Either way it's moving inertially.

Likewise with the weather, you can still analyse it either in an inertial frame where the Earth turns, or in a rotating frame where the Earth is stationary. Only in the latter case (which is the convenient approach for us, as we're sitting on the planet and rotating with it) will Coriolis force appear in the explanation.

Lnewqban and vanhees71
Science Advisor
Homework Helper
So winds going in straight line so cirular motion is just illusion looking from rotating frame?
When a hurricane rotates, that rotation is very real and occurs in both the inertial and rotating frames. One can think of it from the rotating frame as being due to the Coriolis force.

Let us consider a hurricane in the northern hemisphere.

From the rotating frame:

We have this stationary mass of air. In the center, air is forced upward due to its high temperature and high humidity and the adiabatic lapse rate and all that. The result is like a giant vacuum cleaner sucking air out of the middle. As the air moves toward the middle it is deflected rightward by the Coriolis force. The result is a counter-clockwise torque and a counter-clockwise circulation.

From the inertial frame:

We have this mass of air rotating counter-clockwise along with the surface of the earth. In the center, air is forced upward due to its high temperature and high humidity and the adiabatic lapse rate and all that. The result is like a giant vacuum cleaner sucking air out of the middle. Angular momentum is conserved. The air moving upward in the center carries very little angular momentum away. Air entering from the outskirts adds more. The mass of air in the middle must gain rotation rate as a result. So there is a counter-clockwise circulation. [Or think of it as a twirling skater pulling in her arms]

vanhees71, Lnewqban and Aeronautic Freek
Aeronautic Freek
When a hurricane rotates, that rotation is very real and occurs in both the inertial and rotating frames. One can think of it from the rotating frame as being due to the Coriolis force.

Let us consider a hurricane in the northern hemisphere.

From the rotating frame:

We have this stationary mass of air. In the center, air is forced upward due to its high temperature and high humidity and the adiabatic lapse rate and all that. The result is like a giant vacuum cleaner sucking air out of the middle. As the air moves toward the middle it is deflected rightward by the Coriolis force. The result is a counter-clockwise torque and a counter-clockwise circulation.

From the inertial frame:

We have this mass of air rotating counter-clockwise along with the surface of the earth. In the center, air is forced upward due to its high temperature and high humidity and the adiabatic lapse rate and all that. The result is like a giant vacuum cleaner sucking air out of the middle. Angular momentum is conserved. The air moving upward in the center carries very little angular momentum away. Air entering from the outskirts adds more. The mass of air in the middle must gain rotation rate as a result. So there is a counter-clockwise circulation. [Or think of it as a twirling skater pulling in her arms]
Ok thanks..
I just want to know if it really rotates or not,because of so much relativitiy from which point you look something and ficitive forces ,I don't know if I am really alive or just appers to me...🙃

Science Advisor
Homework Helper
I just want to know if it really rotates or not,because of so much relativitiy from which point you look something and ficitive forces ,I don't know if I am really alive or just appers to me...🙃
Different descriptions of the same thing. It "really" doesn't matter which you consider to be real. You are free to pick the description that is most convenient and use it.

Science Advisor
I don't know if I am really alive

That's slightly alarming

vanhees71
Aeronautic Freek
Hm ..
it seems that it has lots of this topics about coriolis ,centrifugal f. etc
I am glad that I am not alone...maybe I am not so stupid as I think...

Aeronautic Freek
That's slightly alarming
Look,maybe from inertial frame I am not alive or just apper that I am on earth!