By southern sea, I mean all the sea between Antarctica and Africa/S America/Australia. The pacific ocean is equally vast but yet it’s milder. I was looking at global winds on a website and almost the entire Southern Sea perpetually faces 60+ kmph winds. There are even 3000+ km long stretches of continuous 80 kmph winds. Why?
In: 1893
The Earth rotates and this causes weather to tend to move west to east. This includes the powerful jet streams but also weather systems such as storms. Of course there are other factors involved in the movement of the weather systems so some do move in other directions but most of them tend to move from west to east. In the Pacific Ocean this means that most weather systems will end up close to the Americas where the land will slow them down. However in the Southern Sea there is no land to hit. The same storm can circle the Earth multiple times building up speed and power over time. That can make these storms enormous.
> There are even 3000+ km long stretches of continuous 80 kmph winds. Why?
You mean the Roaring Forties? They’re one of the world’s prevailing winds which are caused by a combination of temperature differences between the tropics and the poles, and the Coriolis effect (caused by the earth’s rotation). Some latitudes have westerly winds and others have easterlies. There are differences between surface winds and the winds at altitude too.
The ocean between South America and Australia *is* the Pacific my guy…
Do you mean the Southern Ocean? Because that is much, *much* smaller than the Pacific and only really encircles Antarctica below the 60°S latitude.
Or do you mean the Southern Ocean, and those bits of Pacific, Atlantic, and Indian Oceans that intersect?
The currents can circumnavigate the globe without running into a land mass, allowing them to grow pretty strong. This isn’t necessarily a bad thing. The issues arise when those currents run into the southern points of the America’s and Africa. The land masses disrupt these strong, predictable currents in unpredictable ways. Those also happen to be spots with a lot of maritime traffic.
There is no landfall for any of the Souther Ocean. On top of that are the Roaring Fourties Winds down there. High wind, no landfall = huge waves and rough seas.
What would slow the wind down?
Wind.
The entire circumference at that latitude is just ocean. Wind whips around the entirety of the Earth at the latitude and encounters no landmass to abate it.
This leads to incredible sea state
How did sailors handle this 300-400 years ago?
The Sea is rough because of the wind. The Wind is strong because of the massive low pressure zones created by having ocean water present that is usually warmer than the air above. Significant winds are generated due to these massive air pressure differentials. Same thing happens in the northern hemisphere too which experiences the most severe pressure differentials in winter.
There are a lot of comments about currents but the southern ocean currents are slow and insignificant compared to equatorial currents, gulf stream etc.
Professional sailor here. In part it’s the ability for waves to circle the planet as swell (waves that have left the area they formed.). Waves and swells from the north also feed into the area. Everything true for the sea is true for the storms above. Without landmass to break up the wind it blows over longer distances creating a larger fetch (area where waves are generated). The Cape of Good Hope and Cape Horn in particular are areas where storms converge. Messy and chaotic seas to say the least.
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