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Earth Science

Ocean Currents Explain Why Northern Hemisphere Is Soggier 35

Posted by Unknown Lamer
from the stealing-the-rain dept.
vinces99 writes "A quick glance at a world precipitation map shows that most tropical rain falls in the Northern Hemisphere. The Palmyra Atoll, at 6 degrees north, gets 175 inches of rain a year, while an equal distance on the opposite side of the equator gets only 45 inches. Scientists long believed that this was a quirk of the Earth's geometry – that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. But a new University of Washington study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away. The findings, published (paywalled) Oct. 20 in Nature Geoscience, explain a fundamental feature of the planet's climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa's Sahel region and southern India."
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Ocean Currents Explain Why Northern Hemisphere Is Soggier

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  • by justthinkit (954982) <floyd@just-think-it.com> on Monday October 21, 2013 @09:36AM (#45187685) Homepage Journal
    Isn't most of the land in the Northern Hemisphere? When clouds are forced to go upward to pass over a land mass, they are more inclined to drop their rain load. Isn't that basically how it all works?
    • by TWX (665546)

      Isn't most of the land in the Northern Hemisphere?

      Which means, by default, that the Southern Hemisphere is soggier, given that it's got more water sitting on it and all...

      • The Southern Hemisphere's oceans are very soggy. That's what you meant, right?
        • by bondsbw (888959)

          I've been under the impression that the oceans are all equally soggy, regardless of hemisphere.

          • by TWX (665546)
            A given quantity of ocean is as soggy as any other equivalent quantity of ocean, and there's more of that ocean in the southern half of this planet. Hence the southern hemisphere is more soggy, QED.
    • by ShanghaiBill (739463) on Monday October 21, 2013 @11:56AM (#45189437)

      Isn't most of the land in the Northern Hemisphere?

      Yes. But that doesn't explain why the Northern Hemisphere gets more rain even thousands of miles from any significant land mass. The Palmyra Atoll [wikipedia.org] is in the middle of the Pacific Ocean, about as far from any continent as possible. Yet it still gets significantly more rain than similar islands south of the equator.

  • by RivenAleem (1590553) on Monday October 21, 2013 @09:41AM (#45187757)

    Northern hemisphere is on top, southern hemisphere is underneath, rain falls downwards. TBH it's a miracle that rain falls in the southern hemisphere at all. I think they use magnets.

    • It's a good thing Europe was civilised first, otherwise it would the other way around...

    • by wallsg (58203)

      Northern hemisphere is on top, southern hemisphere is underneath, rain falls downwards. TBH it's a miracle that rain falls in the southern hemisphere at all. I think they use magnets.

      We should launch rockets from Australia. All you have to do is let them go and they'll fall into orbit. It would save a lot of fuel.

      • Did you know also, that because of its location, all the air pools down in the southern hemisphere, so much so that its density is higher than that of cork, which is why Australians wear it on their hats to help them stick to the ground better.

  • by Anonymous Coward on Monday October 21, 2013 @10:53AM (#45188699)

    From what I remember of my climatology course, rainfall is tightly tied to the oceanic currents. In the northern hemisphere there are a lot of things going on. We have more land mass, resulting in more "circles" of currents [wikipedia.org]. The axis of the earth impacts insolation [wikipedia.org] and global wind patterns [wikipedia.org], which create areas of evaporation and condensation at particular lattitudes on the earth. These currents change with the elevation of land mass, but by and large hard rock doesn't hold heat nearly as well as water, so you get a (sometimes drastic) temperature difference and condensation above land, which of course results in various wind patterns and rainfall. What is also interesting is look at the deserts of the northern hemisphere, notice how they are all at the same latitude?
      This stuff has been known for years, I'm not sure how this is really "news".

    • My first thoughts... the ocean currents are not the cause. Its the damn shape of the continents and ocean floor that is the real cause. Oh, wait, its the tectonic forces over millions of years... but hang on, its more the heat resulting from gravitational compression that.....oh no, basic physics is to blame for this unfairness.
  • From TFS:

    The findings, published (paywalled) Oct. 20 in Nature Geoscience, explain a fundamental feature of the planet's climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa's Sahel region and southern India."

    The musical act Toto was unavailable for comment.

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