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Dear Capt. Joe Kliment,

I don't know, why you use the low travelling from S to N for your illustration 
of the changing direction of wind in a low). Maybe it is motivated by your 
personal or regional experience, but generally these lows are rather rare. In 
textbooks, the low runing from W to E is invariantly used for this purpose, 
with two observers to S (wind turning S ->SW->W->NW->N)  and N 
(S->SE->E->NE->N, both cases for the northern hemisphere) of its path, as in 
the most cases, the observers to the E and W of the low experience the wind 
of a steady direction (cca N or S), only its strength is changing. Of course, 
this is only an idealized case, but we all use such simplified patterns in 
this discussion.

As for the theme itself, I skimmed through my scarce texts on meteorology in 
English and I suppose that they use "backing / veering" for northern regions, 
but more general terms (e.g. "shifting / turning" with subsequent details) 
when the southern hemisphere is explicitly meant, so as to avoid a 
misunderstanding. U.S. Sailing directions for Australia (1931 and later) 
provide a clear example.


Jan Kalivoda


----- Original Message -----
From: "kliment" 
To: 
Sent: Saturday, January 25, 2003 5:08 AM
Subject: Definition of Term


> In the northern hemisphere high pressure systems are associated with
> clockwise winds(anticyclonic) while low pressure systems are associated with
> counterclockwise winds(cyclonic). This is opposite in the southern hemisphere
> with counterclockwise highs and clockwise lows. Your location
> with respect to a low will dictate whether the wind will "back" or "veer"
> as the low passes. In the northern hemisphere if the low passes east of
> your location the winds will "back" from NE ,N, NW,  to W and if the low passes
> west of your location then winds will "veer" from NE, E, SE, to S.
>
> By applying Buys Ballot's Law you can determine the location of the center
> of the low and
> predict it's path with either "backing" or "veering" winds.
>
> Capt Joe Kliment
> W3HZM
> Middletown,De.

   

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