Re: The weather and the many different factors that drive it...
From: Eric Swanson (swanson_at_notspam.net)
Date: 03/12/05
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Date: Sat, 12 Mar 2005 16:59:29 +0000 (UTC)
In article <d0uik3$dlt$1@newsg1.svr.pol.co.uk>, alastair@abmcdonald.leavethisout.freeserve.co.uk says...
>
>
>"Eric Swanson" <swanson@notspam.net> wrote in message
>news:d0t4cm$eue6$1@news3.infoave.net...
>> In article <42320f3b$1_1@127.0.0.1>,
>peter.bantick@tiscali.co-dot-uk.no-spam.invalid says...
>> >
>> >hi everyone,just thought I'd make a topic on the weather and also the
>> >many different factors and how everything forms(this will be a very
>> >long post but hopefully very informative..so firstly we should start
>> >off wih some basics.
>> >
>> >For those who don't know what those "Highs" and "Lows" stand for on
>> >the charts here is a brief description of them,which you will
>> >hopefully understand,Air pressure is a measure of how much air is
>> >pushing down on the surface of the Earth at a given point. Generally,
>> >high- and low-pressure systems form when air mass and temperature
>> >differences between the surface of the Earth and the upper atmosphere
>> >create vertical currents. In a low-pressure system, these vertical
>> >winds travel upwards and suck air away from the surface of the Earth
>> >like a giant vacuum cleaner, decreasing the air pressure above the
>> >ground or sea. This decrease in surface air pressure in turn causes
>> >atmospheric currents moving parallel to the surface of the Earth near
>> >the base of the low to spin counter clockwise (clockwise in the
>> >Southern Hemisphere). Conversely, in a high-pressure system, air is
>> >being pushed down on the ground like a vacuum put in reverse. The
>> >downward vertical winds cause an increase in air pressure on the
>> >ground and force atmospheric currents to spin clockwise (counter
>> >clockwise in the Southern Hemisphere). Both lows and highs function
>> >like giant slow-moving hurricanes and anti-cyclones, respectively.
>> >The higher in pressure a high-pressure system gets or the lower in
>> >pressure a low-pressure system gets, the more robust and larger this
>> >spinning circulation pattern becomes.
>>
>
>Well, that is a nice friendly remark!
>
>> First off, vacuums can't "suck" a fluid.
>
>He said vacuum cleaners, not vacuum, which do in fact suck!
Vacuum cleaners push the air out of an enclosed space. The resulting
low pressure allows the air from outside to push into that space. "Sucking"
is the result of pushing the air out, not pulling the air into the space.
A fluid can not produce a static tension force, only a pressure force.
>Sorry to bust your bubble, but your beginning (and likely/////// everything
>else) is very wrong.
>
>
>> The force of gravity doesn't
>> push the air towards the earth, it pulls it.
>
>The weight of the air above a point pushes the air beneath it and that is
>what we measure when we measure air pressure - a push from the air
>above, not the gravitational force on the surrounfing air molecules!
Learn some physics. The "weight" of the air is due to the gravitational
pull on the mass of air above. The "weight" of the same column of air
would be less on Mars and greater on Jupiter.
>> The rotation of an airmass
>> is due to the Coriolis Effect, as air moves from one latitude to another.
>> In the NH, the highs rotate in a clockwise direction, while in the SH,
>> they rotate the other way. The low pressure areas are the result of
>> horizontal horizontal motions in the atmosphere and vorticity, that
>> is, the tendency for a fluid to maintain its rotation.
>>
>> http://www.answers.com/coriolis+effect&r=67
>
>If the Coriolis effect is due to the rotation of the Earth affecting the
>flow of air from one latitude to another, why do anti-cyclones rotate
>in one direction and depressions in another? (BTW. That was a
>rhetorical question requiring no answer. There are plenty of specious
>arguments used to justify the misuse of the Coriolis effect.)
Lets consider the situation in the NH. Warm air masses moving toward the pole
tend to rotate clockwise, due to the conservation of momentum. That is, the
air has an eastward velocity close to that of the ground below it, but, as
the air mass moves to a higher latitude, the rotational radius of the ground
below is reduced, thus the eastward velocity of the ground is less. As a
result, the air mass appears to have an ever increasing eastward velocity
when viewed from the surface. The same effect happens in reverse as (usually)
cold air masses flow back from the pole toward the tropics, except that the
ground has a greater velocity to the East than the air mass as the latitude
is decreased. Thus, the flows look as if they rotate. Along the boundaries
of the air masses, the velocities of the air move in opposite directions, thus
low pressure storms form with counter clockwise rotation. Once the rotation
of a storm begins, vorticity (again, conservation of momentum) keeps the
rotation going until it is damped out by drag. Hurricanes are a bit different,
developing from warm air which rises above a warm ocean surface.
>> Might I suggest that you would benefit by reading an introductory college
>> level text on meteorology?
>
>Might I suggest that you would benefit by ceasing to read introductory college
>level texts on meteorology, and start thinking about some of these problems
>for yourself, much as it appears climateshift has done!
If one doesn't know the basics, then one is likely to misunderstand what one
percieves to be happening to climate.
-- Eric Swanson --- E-mail address: e_swanson(at)skybest.com :-) --------------------------------------------------------------
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