May 2, 2011 - You Go, Gulf Stream


Back in the old days, when there were no such things as telephones or computers, let alone cell phones and 4-G and the internet and WiFi, there were these things called letters. People would write on this stuff called paper, and they would get someone to physically carry their letters from one place to another. Sounds pretty slow, right?

Well, in the 1700s, Benjamin Franklin noticed that mail coming to America from Europe was even slower than the mail going from America to Europe. Boats crossing the Atlantic Ocean could travel westward at least a couple of weeks faster than boats traveling eastward.

An ocean current that acts like a river on the ocean is responsible for this extra speed. Although American whalers and some other seagoing people knew about this current by the 1700s, the knowledge wasn't as widespread as I'd imagined it would be. American whaling captain Timothy Folger told his cousin, Benjamin Franklin, that American whalers had explained to English sea captains how to use the current for maximum speed—but, he went on to say, the Brits had ignored the advice. Folger said the English captains were a bit snobbish and thought themselves “too wise to be counseled by simple American fishermen.” 

Benjamin Franklin was intrigued. He began a scientific study of the current in the Atlantic, measuring the temperatures of the water two or three times a day on his voyage home from England, and noting the water color and any seaweed he saw. Some sources claim that he completed his study on this day in 1775. 

Franklin and Folger drew charts to show the location of the current. (Studies today, including satellite data, show that these early charts were remarkably accurate. By the way, did you know that we use the word charts for water in the same way we use the word maps for land?) 

Franklin explained the cause of the current—the accumulation of water on the eastern coast of America due to the constant trade winds. (Basically, he was right.) 

And Franklin named the current Gulf Stream. (We still use the name today.)

Still Important

Even though speed-of-light communication via electronic transmission and satellites has left the old moving-pieces-of-paper kind of communication behind in the dust, we still trade goods and catch fish and even travel by ship--and we still want to go with the current when traveling eastward across the Atlantic Ocean, and to avoid going against the current when traveling westward.

But there is another reason the Gulf Stream is so important: climate.

You see, the Gulf Stream is made up of warm water traveling up from the tropics and over the ocean to the British Isles. As it moves into colder areas of the world, the water slowly cools, of course—but it is still warm enough, when it reaches Europe, to keep England warmer than it would be without the Gulf Stream.

Grab a globe and use it to check the latitude of England—and then compare that latitude to areas in Canada and Russia that are the same latitude. A little digging will show you that England's climate is milder than it ought to be, if latitude were the only factor:

  • London's average temperatures range from 45 to 58 degrees F (7 to 14 degrees C).
  • At around the same latitude, parts of Siberia enjoy temperatures from 28 to 44 degrees F (-2 to 7 C). Much colder!
  • And at about the same latitude, the southern part of Labrador in Canada is classified as sub-arctic. The average temperatures range from -18 to 65 degrees F, and there is snow cover for months every winter.

Here is another chart from the pen of Benjamin Franklin.
It shows that he realized that the Gulf Stream is actually a loop.

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