Friday, December 13, 2019

The Magical Roaring Forties – Part I

Since Nephi makes it crystal clear that the ship he built was propelled by the winds and currents from the land of Bountiful where he built it, all the way to the Land of Promise. Not only was it his original propulsion: “And it came to pass after we had all gone down into the ship, and had taken with us our provisions and things which had been commanded us, we did put forth into the sea and were driven forth before the wind towards the promised land” (1 Nephi 18:8, emphasis added), and later, was still being driven by the winds and currents: “And it came to pass after we had all gone down into the ship, and had taken with us our provisions and things which had been commanded us, we did put forth into the sea and were driven forth before the wind towards the promised land” (1 Nephi 18:9, emphasis added).
Red Dotted Line: Lehi’s course along the existing currents of the Indian Ocean, first south down the Arabian Current, then picking up the Southwest Current past Africa, then moving into the Indian Ocean Gyre that swings the ship to the southeast, around the Gyre to the 40º South Latitude where the ship could be steered into the Roaring Forties or West Wind Drift
To verify this and understand why these winds and currents exist, it would be important to know how the wind and currents move, where and how they flow, in order to understand where Nephi was sailing—this in turn will tell us how he got to the Land of Promise and where it was located, a point that can be verified by what Nephi states they found where they landed (1 Nephi 18:24-25).
    So what winds and currents were available to them as they “put forth into the sea and were driven forth before the wind towards the promised land.” Thus, we see that the currents from the point of marking to the point of landing blew in that direction, and the waves and currents flowed in that direction.
    Consequently, we need to understand not only which winds and currents were available to Nephi in which to guide his ship, but to recognize these winds and currents are determined by numerous scientific principles and systems that have, do and will always so affect the atmosphere and ocean’s surface.
    So what winds and currents were available?
    First, upon entering the Indian Ocean, the ship would have been caught in a counter-clockwise circular ring of ocean current called the Indian Ocean Gyre.
    Unlike any other current in the world, the ocean now called the Southern Ocean has three divisions that run horizontally around the world, making up the fastest current on the planet. The first of these divisions is called the Roaring Forties. This is a strong current driven by the westerly winds found in the Southern Hemisphere, generally between latitudes 40º and 50º.
    These strong west-to-east air currents are caused by the combination of air being displaced from the Equator towards the South Pole, the Earth's rotation, and the scarcity of landmasses to serve as windbreaks. During the Age of Sail, the Roaring Forties were a major aid to ships sailing the Brouwer Route, which was a 17th-century route used by ships sailing from the Cape of Good Hope (Africa) to the Dutch East Indies, as thre eastern leg of the Cape Route. This took ships south from the Cape (34º south latitude) into the Roaring Fortis, then east across the Indian Ocean before turning northeast for Java. Thus it took advantage of the strong westerly winds for which the Roaring Forties are named, greatly increasing travel speed (Dutch Chartering of Australia 1606 to 1756, Naational Archief of the Netherlands, National Library of Australia, 22 September 2006).
Australasia (Australia, New Zealand, and some neighboring islands) and the three major currents of the Southern Ocean

These early ships sailed from the East Indies or Australasia during the Age of Sail. In fact, modern usage of these strong and fast winds and currents are favored by yachtsmen on round-the-world voyages and competitions, such as the Times Golden Globe race, The Clipper race or the Round the World race.
    The boundaries of the Roaring Forties are not consistent, and shift north or south depending on the season. Similar but stronger conditions occurring in more southerly latitudes are referred to as the Furious Fifties and the Shrieking or Screaming Sixties.
    The mechanics of the Magical Roaring Forties results from hot air rising at the Equator, which is pushed towards the poles by cooler air traveling towards the Equator (an atmospheric circulation feature known as the Hadley Cell). At about 30 degrees from the equator, the outward-traveling air sinks to lower altitudes, and continues toward the poles closer to the ground (the Ferrel Cell), then rises up again from about 60 degrees as the air joins the Polar vortex—a whirling mass of cold air circulating in the mid- to upper-levels of the atmosphere, present every winter, and usually stays closer to the poles. Unfortunately, the vortex occasionally breaks apart, sending chunks of frigid arctic air southward into the U.S. during winter.
    In the Southern Latitudes, this vortex travels in the 30º to 60º zone, and combining with the rotation of the earth air currents are moved from west to east, creating westerly winds.
    Unlike in the northern hemisphere, the large tracts of open ocean south of the 40th parallel south, which is interrupted only by Tasmanias, New Zealand and the southern [art of South America, allow higher windspeeds to develop. Similar but stronger wind conditions prevalent closer to the South Pole are in the area of the "Furious Fifties" and the "Shrieking" or "Screaming Sixties.” The latitude ranges for the Roaring Forties and similar winds are not consistent, shifting towards the South Pole in the southern summer, and towards the Equator in the southern winter.
The speedy Clipper Route was the traditional route derived from the Brouwer Route and sailed by clipper ships between Europe and the Far East, Australia and New Zealand

The Clipper Route was taken by ships sailing from Europe to Australia in order to take advantage of the Roaring Forties and increase the speed of their journeys. During the Age of Sail, ships traveling from Europe to the East Indies or Australasia would sail down the west coast of Africa and round the Cape of Good Hope to use the Roaring Forties to speed their passage across the Indian Ocean (I.C.B. Dear and Peter Kemp, “Roaring Forties,” Oxford Companion to Ships and the Sea, Oxford University Press, U.K., 2007).
    On the return leg, the ship would continue eastwards across the Pacific Ocean and under Cape Horn before sailing up the east coast of the Americas to home.
Dutch captain Hendrik Brouwer discovered a quicker trade route to Indonesia’s spice islands which halved the time it took to reach Indonesia by using the ‘roaring forties’ to speed the passage of ships in an easterly direction

Dutch explorer Hendrik Brouwer was the first to bring a European ship into close contact with the coast of Western Australia that in 1611 was known as “The Unknown South Land.” Prior to this, the route to Indonesia after rounding the Cape of Good Hope was to sail northward up the African coast and then across the Indian Ocean to Sumatra and Java (The East Indies). However, Brouwer discovered that by continuing on after rounding the Cape directly across the Southern Ocean to near Australia, then turning northward directly to Java and Indonesia (East Indies).
    Because of the speed of the Roaring Forties, Brouwer found he could travel from the Caper to Java in half the time as with the previous rout up the African coast.
(See the next post, “The Magical Roaring Forties – Part II,“ for more information about the winds and currents and how they drove Lehi to the Land of Promise)


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  2. I recall Del has written about the season Lehi must have left Salalah but remind me when that was?

    It is clear looking at the currents that there are only specific times when they could have left.

    This adds more meaning to 1 Nephi 18:5

    5 And it came to pass that the voice of the Lord came unto my father, that we should arise and go down into the ship.

    Not only did the Lord prepare the way for them but He told them the right time to go. (There’s another lesson in there about Lehi doing what the Lord told him to without procrastinating).

    Thanks to those who provided the live view of the currents in the link below. Del has done an excellent job over the years describing how you have to start where Lehi departed and see where the currents can take you rather than pretend they could have gone anywhere. But being able to see the currents live ourselves makes it easier to understand.,17.09,3000/loc=54.062,16.952

  3. The months when the wind most likely blows southward (seaward) from Salalah is December and January. See graphs here, among other weather pages for Salalah:

    So keep an eye on that part of the coast this month and next for your launch window.

    Nullschool Earth website is a great tool to watch that wind direction.