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Southern Hemisphere Weather

Southern Hemisphere Weather

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Is there also a jet stream in the southern hemisphere that flows from east to west?? It seems I may have heard that somewhere. Does it affect our weather in the Northern hemisphere? Also, how quickly can the jet stream change positions. Does it take days to be manuevered by a low or high pressure, or does the jet stream move the high and low pressures; can it take place in the matter minutes. I know a storm can come in quickly but does it take days to break down the high or low?

Ann S.


So many questions, so little time! Check it out, jet streams come from temperature contrasts which then create pressure differences. It's that difference in pressure, the pressure gradient force or the PGF that makes wind, the jet! In the northern hemisphere our cold our air in the north, warm air in the south, we get some neat air flows going on with these temperature contrasts. The angle of the sun contributes to location of our poles and where the air is coldest.

In the southern hemisphere the Antarctica and the South Pole is where the coldest air is and it gets warmer as you head equator-ward. This big contrast in temperatures will also create a jet stream. Remember though, there's less land mass in the southern hemisphere too, so that plays a difference in the strength of the jet stream. We need temperature contrasts to really get it going and over a whole area of ocean, the contrasts won't be as high.

The jet stream in the Southern Hemisphere or SH will also move from west to east due to the Coriolis Force. This force comes from the rotation of the earth! This jet does not flow the opposite way of the jets in the north. Air is always moving from cold to warm. Weather systems that are smaller like areas of low pressure will spin the opposite way with their internal flow. But they'll still move east to west.

The SH jet doesn't effect the weather in the northern hemisphere.

The jet stream is always moving but to actually move the whole thing over areas of latitude would take a few days. The jet controls the movement of the high and low pressure, not the other way around. There are smaller scale features, like hurricanes which are not so much jet dependent.

The jet doesn't really "break" a high or low. It can weaken or strengthen systems. Again, probably a couple of days, definitely not a day or an hour.

There's a link on the right to more FAQ's on jets.

Answered by KSL Meteorologist Dina Freedman.

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