Jet stream question

[Joffreyyy]

Why does the southern hemisphere jet stream go west to east like the northern hemisphere; wouldn’t coreolis effect make it go east to west ?

 

[bflynn]

Yes, you're right. Nature has it all wrong.

 

[Cap'n Jack]

The jet stream is (mainly) one direction and tends not to cut lines of latitude (yes, over simplification). So its movement doesn't change relative to the rest of the earth. Perhaps a better question might be why do the jet streams move a particular direction at all.

 

[kath]

The Coriolis effect deflects moving things to the right in the North, and to the left in the South.
Air tends to move from the equator towards the poles.**
Air masses at around our latitude in the North are moving towards the North Pole, so "to the right" is East.
Air masses at similar latitude but in the south are moving towards the South Pole, so "to the left" is East again.

**gross oversimplification? is this actually the reason?

 

[Shepherd]

Close enough for government work.

 

[Joffreyyy]

The Coriolis effect deflects moving things to the right in the North, and to the left in the South.
Air tends to move from the equator towards the poles.**
Air masses at around our latitude in the North are moving towards the North Pole, so "to the right" is East.
Air masses at similar latitude but in the south are moving towards the South Pole, so "to the left" is East again.

**gross oversimplification? is this actually the reason?

That’s what I thought too but I saw many pictures of all 4 jet streams going west to east.. thus the confusion

 

[chemgeek]

That’s what I thought too but I saw many pictures of all 4 jet streams going west to east.. thus the confusion

Yes both the polar and subtropical jets all flow from west to east along boundaries of large convection cells that transport hotter lower latitude air northward where it cools and sinks. Coriolis force deflects the rising air eastward as it flows poleward. This is a consequence of the direction of the earth's rotation eastward.

 

[Cap'n Jack]

The Coriolis effect deflects moving things to the right in the North, and to the left in the South.
Air tends to move from the equator towards the poles.**
Air masses at around our latitude in the North are moving towards the North Pole, so "to the right" is East.
Air masses at similar latitude but in the south are moving towards the South Pole, so "to the left" is East again.

**gross oversimplification? is this actually the reason?

Hi Kath! Haven't seen you post for a while, or maybe I missed them. Hope you are well!

Yes both the polar and subtropical jets all flow from west to east along boundaries of large convection cells that transport hotter lower latitude air northward where it cools and sinks. Coriolis force deflects the rising air eastward as it flows poleward. This is a consequence of the direction of the earth's rotation eastward.

I think both of you are starting to describe the mechanism as to why the jets blow to the east, though I'm not seeing it stated very clearly to me.
It seems the jets flow from west to east because the air that moves into, and creates the jet streams, has momentum eastward as it moves into the jet. This momentum is from the movement into the jet stream from north or south (see image). The image in post 6 shows the jet streams at the same latitudes as the boundaries for the Hadley/Ferrel cells, and the Ferrel/Polar cells in the image below.