Horse Latitudes ( from The complete idiot's guide to... staying in
circulation.)

"Farther north and south, around 30 degrees north and 30 degrees
south, the surface wind diverges, so air must sink to replace it. That
sinking creates high pressure, sunny skies dry air and tons of
evapouration. Many of the worlds deserts are found at thislatitude.The
divergence causes very light winds. The high pressure system is
centred here. In days of old, explorers heading for the new world ran
into cals within this zone. The ships wouldn't move, so they tossed
everything they could spare overboard to lighten the load, including
their horses. So, the region became known as the horse latitudes."

Hardly encouraging one to read on is it?

What sort of idiot... oh, wait...

OK.

For future reference it isn't:
"around 30 degrees north and 30 degrees south"

It is:
'around thirty degrees latitude'
or
'around thirty degrees north and south...'

Sheesh!!

I have this saved on my PC as a text file (using Mandriva with Gnome.)
The file has an icon that reads: "Horse *Fart".
How appropriate.

But the paragraph called to mind a "nice" point.
Over the equator, more or less, the weather is markedly orographic.
You can almost set your watch and your calender by it.

I was looking up "orographic" in the index as I am not sure that is
the term I am after. It isn't in there. (That figures.) I came across
"ordovician" though and took the trouble to find out what one of them
was.

"Earth's history can be described within certain time intervals. The
largest subdivisions are called eras. The precambrian era is the
oldest era within which the first organisms appeared between 700
million and 3.4 billion years ago. Then there is the paleozoic era,
which is further divided into periods. These periods include the
ordovician period, when the first vertebrate fossils apeared. That was
400 to 500 million years ago last wednesday. The first amphibians
appeared during the devonian period..."

Shouldn't that be:
The first amphibians appeared during the neobracknellian period?

A minor point for budding geologists:
You are far more likely to find extinct zoophilum in precambrian rock
as it predates the period god made the grass grow. That is why to this
day in the harshest deserts, the only signs of life are dead animals
and live horse disposal engineers. The dead animals are there because
either they made a mistake or god did. Presumably the other examples
were looking for Exitzoer?

"Weatherlawyer" wrote in message
...
Horse Latitudes ( from The complete idiot's guide to... staying in
circulation.)

Horse latitudes? Are you trying to gee everybody up?

"Lawrence Jenkins" wrote in message
...
|
| "Weatherlawyer" wrote in message
| ...
| Horse Latitudes ( from The complete idiot's guide to... staying in
| circulation.)
|
| Horse latitudes? Are you trying to gee everybody up?
|

The reason they are known as the "horse latitudes" is explained in the
quoted text in the original post.

The dynamical explanation of the calm winds, however, is totally out. What
is observed at the surface is not the cause of the high pressure, but the
result of the process which actually is in operation.

Warm air rising near the equator (by convection in the Inter-Tropical
Convergence Zone) heads polewards at high altitude. As it does so, it is
deflected eastwards (to the right in the Northern Hemisphere) by the effect
of air moving over the rotating earth we call the "Coriolis force". This
air effectively "piles up" aloft at the latutudes referred to, resulting in
a rise of pressure at the surface. Winds there then flow away from the high
pressure and air sinks from aloft to replace it.

The equatorwards side of this circulation is known as the Hadley Cell and
drives the "Trade Winds" observed in the sub-tropics. The polewards side
(which feeds the westerlies known to those of us in the UK) is the Ferrel
circulation. If you search for these you should fnd a fuller and more
accurate explanation than the extremely rough one I have provided.
--
- Yokel -

"Yokel" posts via a spam-trap account which is not read.