The mighty deep : $b and what we know of it — John Shaqi
The mighty deep : $b and what we know of itGiberne, Agnes
Science
The mighty deep : $b and what we know of it
Giberne, Agnes
Marine biology; Nature study
When a storm-wind pours up a narrowing gulf, where the sea has no
outlet, it often piles the water up in an extraordinary manner.
Hurricanes have been known to turn the entire Gulf Stream for a while
out of its course, and even to force the waters back so as actually
to reverse the current. Once the volume of water, thus checked by a
terrific gale, was heaped up some thirty feet above the proper level,
which of course caused a fearful deluging of the land.
The above words had not been long written, when papers told us of the
awful hurricane of September, 1900, in U.S. Texas. A deep cyclone
passed over the devoted town of Galveston, the direction of the wind
suddenly changing as the centre of the cyclone went by: and the
heaped-up waters from either side coming together poured their united
volume over the land.
That was a flood which “turned the city into a raging sea.” Buildings
were levelled; houses fell like packs of cards; vessels were carried
miles inland; men and women and children perished by thousands. When
the lessening wind allowed the waters to retire, an inch-deep layer of
slime was found over everything.
Such facts as these help to show how vast is the power of moving air
over the ocean.
As a strong wind blows, the upper layer of water slips along in
obedience to its push; and fresh lower surfaces are bared to the same
influence. Also, the movement of the upper layer tends to drag on
the layer just below, which again affects the one lower still. By
influence thus exerted and passed from one to another, the result of a
long-continued wind-pressure in one direction is to set going powerful
streams, which in the first instance were due chiefly or only to wind.
Round the Earth, where fairly open sea permits them to develop, are
two wide belts of very persistent winds--the Trades--which remain
practically the same all the year round; only shifting their limits
with the changing seasons.
They blow from the north-east and from the south-east slanting towards
the equator. So, speaking roughly, they are easterly winds travelling
towards the west. As a consequence of their steady pressure, we have
the great Equatorial Current of the tropics, pouring from east to west
in two halves, north and south of the equator. This vast ocean-river,
started and kept going by the trade-winds, has been described in the
more important part of its course as a “magnificent surface-current of
hot water, four thousand miles long by four hundred and fifty broad,”
moving “at an average rate of thirty miles a day”--and, it may be
added, at least over six hundred feet in depth.
Between the Trade-wind belts is a belt of dead calms, known to sailors
as “The Doldrums.” This belt divides in two the Equatorial Current; and
in it is found the inevitable “Counter Current,” mentioned earlier,
flowing from west to east.
Public-domain text, read in full here on John Shaqi.
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