Why do hurricanes always turn north, away from the Equator?

[physicsponderer]

To Vanadium:

It seems you are right. It was much nearer than I thought possible, only about 200 km from the Equator. And if it was (hypothetically) 500 km in radius, then in a sense it touched or even crossed it, perhaps. But the diagram showed only the path of its centre or centre of mass or something.

I posted the above in reply to one of your posts, so obviously I know that hurricanes are big, and not points.

 

[physicsponderer]

You seem to think a Hurricane is a point object. They are big. When they (rarely) form near the equator, they influence the weather on both sides. You can't just talk about the eye, because many storms don't have a well-formed or visible eye.

Here's Wikipedia's picture of Cyclone Agni. Can you spot the eye? And isn'tg it pretty clearly in both hemispheres?

View attachment 274678

The centre would seem to be about two degrees north of the Equator. What is making the wind spiral inwards I wonder? That is a very interesting picture. I thought that wasn't supposed to be possible. I guess by chance there was enough anticlockwise angular momentum locally so the Coriolis effect was not needed.

 

[PeterDonis]

This is very interesting. It seems to be very authoritative.

It's not. It's someone's personal site, not a textbook or peer-reviewed paper.

As for the content, see my comments in post #14.

 

[PeterDonis]

obviously I know that hurricanes are big, and not points

Maybe you know it, but you don't seem to be thinking very carefully about its implications. To name just one: since the direction of airflow (wind) varies from one place in the hurricane to another, whatever Coriolis effect exists on the airflow will vary from one place in the hurricane to another as well. So considering the hurricane to be a single object with a single Coriolis effect applied to it is obviously wrong. Yet that is what you are trying to do.

 

[physicsponderer]

Maybe you know it, but you don't seem to be thinking very carefully about its implications. To name just one: since the direction of airflow (wind) varies from one place in the hurricane to another, whatever Coriolis effect exists on the airflow will vary from one place in the hurricane to another as well. So considering the hurricane to be a single object with a single Coriolis effect applied to it is obviously wrong. Yet that is what you are trying to do.

Where did I try to do that?

 

[PeterDonis]

Where did I try to do that?

Pretty much everything you have posted in this thread, starting from the very thread title, has an underlying assumption that the hurricane is a single object with a single Coriolis force applied to it.

 

[physicsponderer]

Pretty much everything you have posted in this thread, starting from the very thread title, has an underlying assumption that the hurricane is a single object with a single Coriolis force applied to it.

Well, it has a centre of mass, right?

 

[PeterDonis]

it has a centre of mass, right?

Not really, since it has no definite boundary and air is continually being exchanged across any boundary you choose to draw around it.

 

[DaveC426913]

Well, it has a centre of mass, right?

A swarm of bees has a centre of mass too, but it's entirely useless for determining anything about how bee swarms move.