Why is wind directon expressed as "FROM"?

[JohnH]

Is it me, or is wind direction bass ackwards?

Vectors normally indicate direction an object is moving, but not so with
wind.

Why is that?

[Jose]

> Is it me, or is wind direction bass ackwards?
>
> Vectors normally indicate direction an object is moving, but not so with
> wind.
>
> Why is that?

I suspect it's a holdover from weather. You don't care where wind is
going (for the purposes of weather prediction) but you do care where it
came from (as that gives hints as to what kind of airmass will be
arriving, and what it will bring with it). When wind is coming from New
Jersey, this tells you something. When wind is =going= to New Jersey,
it's their problem. :)

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Peter R.]

JohnH > wrote:

> Is it me, or is wind direction bass ackwards?
>
> Vectors normally indicate direction an object is moving, but not so with
> wind.
>
> Why is that?

Not sure of the official reason, but hearing the wind direction expressed
as a FROM direction provides me with a very quick way of determining which
runway is most aligned with landing into the wind.

For example, landing at an airport with a single strip runway labeled 10 on
one side and 28 on the other, you hear the wind on the ASOS reported as
"250 at 15." What runway will you choose?

--
Peter

[Roy Smith]

In article >,
Jose > wrote:
>> Is it me, or is wind direction bass ackwards?
>>
>> Vectors normally indicate direction an object is moving, but not so with
>> wind.
>>
>> Why is that?
>
>I suspect it's a holdover from weather. You don't care where wind is
>going (for the purposes of weather prediction) but you do care where it
>came from (as that gives hints as to what kind of airmass will be
>arriving, and what it will bring with it). When wind is coming from New
>Jersey, this tells you something. When wind is =going= to New Jersey,
>it's their problem. :)

The usage probably predates aviation, but it certainly does come in
handy for pilots trying to pick the right runway to use. If the ATIS
says the wind is X, pick the runway numbered closest to X and you'll
have a headwind.

[Flyingmonk]

>When wind is coming from New Jersey, this tells you something. When wind is =going= to New Jersey, it's their problem. :)

LOL
The Monk

[Garner Miller]

In article >, Peter R.
> wrote:

> For example, landing at an airport with a single strip runway labeled 10 on
> one side and 28 on the other, you hear the wind on the ASOS reported as
> "250 at 15." What runway will you choose?

The one that lets me roll out closest to the parking area. :-)

--
Garner R. Miller
ATP/CFII/MEI
Clifton Park, NY =USA=
http://www.garnermiller.com/

[Larry Dighera]

On Thu, 5 Jan 2006 11:51:58 -0500, "JohnH" >
wrote in >::

>Why is that?

The convention is probably a result of the way a weather vane works;
the arrowhead points into the wind, so a compass rose placed under it
indicates the direction of the wind's origin.

[Jose]

> The convention is probably a result of the way a weather vane works;

I'd say the opposite - the vane is designed that way because we're
interested in where the hot air came from. :)

One could easily design a vane that worked the other way.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Larry Dighera]

On Thu, 05 Jan 2006 17:49:51 GMT, Jose >
wrote in >::

>One could easily design a vane that worked the other way.

How would you do that?

[Tony]

Make the arrowhead really big and mount the thing by the tail.

Tie a piece of string on a stick and see which way it points.

[Darrell S]

JohnH wrote:
> Is it me, or is wind direction bass ackwards?
>
> Vectors normally indicate direction an object is moving, but not so
> with wind.
>
> Why is that?

The child asked his father, "Why does an elephant have such a funny nose?"
The father thought awhile, then replied, "Cause that's the way it is!"

That's pretty much the logic behind wind direction.

--

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

[Peter R.]

Garner Miller > wrote:

> The one that lets me roll out closest to the parking area. :-)

Let us hope it is not a 1,500 foot strip where the closer parking area
favors runway 10. :)

--
Peter

[alexy]

Larry Dighera > wrote:

>On Thu, 5 Jan 2006 11:51:58 -0500, "JohnH" >
>wrote in >::
>
>>Why is that?
>
>The convention is probably a result of the way a weather vane works;
>the arrowhead points into the wind, so a compass rose placed under it
>indicates the direction of the wind's origin.

I'm pretty sure that is confusing cause and effect. I suspect that the
explanation is the one others have given about the source of the wind
being relevant to weather. Weather vanes could easily have been built
with no "tailfeathers" and a big arrowhead if the convention had been
the other way.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

[[email protected]]

Jose wrote:

> I suspect it's a holdover from weather. You don't care where wind is
> going (for the purposes of weather prediction) but you do care where it
> came from (as that gives hints as to what kind of airmass will be
> arriving, and what it will bring with it).

Actually this is incorrect. Which way the air is moving here and now
doesn't tell us about what weather we can expect in the future, it only
tells us who is going to inherit our current weather. To figure out
what weather we are going to get, you'd have to look at weather that is
being blown towards us by the winds in its area - and for predictions
of more than an hour or two into the future, the location of the
weather being blown towards us may not be that from which our current
local wind is yet arriving.

Of course real weather prediction also looks at things like local
pressures.

[George Patterson]

JohnH wrote:
> Is it me, or is wind direction bass ackwards?

It's just you.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

[Jose]

> Actually this is incorrect. Which way the air is moving here and now
> doesn't tell us about what weather we can expect in the future

In the days before professional weather guessers on TV, it was useful
enough.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Stubby]

JohnH wrote:
> Is it me, or is wind direction bass ackwards?
>
> Vectors normally indicate direction an object is moving, but not so with
> wind.
>
> Why is that?
>
>
>
May the wind at your back be your own.

[Bob Chilcoat]

I suspect that it comes from the days of sailing ships. All of your course
decisions are based on the direction of the wind. Tacking, running,
reaching, etc. are all referred to the current wind direction. I'm not sure
I fully understand why FROM was chosen as the convention, but when you're
sailing, you tend to keep the wind in your face unless you're running.

--
Bob (Chief Pilot, White Knuckle Airways)


"Larry Dighera" > wrote in message
...
> On Thu, 5 Jan 2006 11:51:58 -0500, "JohnH" >
> wrote in >::
>
>>Why is that?
>
> The convention is probably a result of the way a weather vane works;
> the arrowhead points into the wind, so a compass rose placed under it
> indicates the direction of the wind's origin.
>

[Steven P. McNicoll]

"Jose" > wrote in message
. ..
>
> I'd say the opposite - the vane is designed that way because we're
> interested in where the hot air came from. :)
>
> One could easily design a vane that worked the other way.
>

Most weather vanes I've seen are of the simple arrow type. A weather vane
of that type that pointed the other way would be counterintuitive, the arrow
would be "flying" backward.

[Steven P. McNicoll]

"Larry Dighera" > wrote in message
...
>
> How would you do that?
>

The shape doesn't matter. All that's required is greater surface area on
the downwind side of the pivot point.

[JohnH]

>> One could easily design a vane that worked the other way.
>>
>
> Most weather vanes I've seen are of the simple arrow type. A weather
> vane of that type that pointed the other way would be
> counterintuitive, the arrow would be "flying" backward.

In which case is a windsock confusing?

If we used standard vectors, the tail could be arrow shaped, lose the tail
and save 50% in parts costs ;)

[Steph]

"Darrell S" > wrote in message
news:xjdvf.4685$B93.1548@fed1read07...
> JohnH wrote:
>> Is it me, or is wind direction bass ackwards?
>>
>> Vectors normally indicate direction an object is moving, but not so
>> with wind.
>>
>> Why is that?
>
> The child asked his father, "Why does an elephant have such a funny nose?"
> The father thought awhile, then replied, "Cause that's the way it is!"
>
> That's pretty much the logic behind wind direction.
>
> --
>
> Darrell R. Schmidt
> B-58 Hustler History: http://members.cox.net/dschmidt1/
> -
>
>

In the old days of sail, long before the compass was divided into 360
degrees, or even "points", the classical Greeks and Phoenicians really only
recognised 4 primary winds - north, south, east and west.
The north wind came from - guess where?

[Steven P. McNicoll]

"JohnH" > wrote in message
...
>
> In which case is a windsock confusing?
>

None that I can think of.


>
> If we used standard vectors, the tail could be arrow shaped, lose the tail
> and save 50% in parts costs ;)

If you lose the tail you lose the ability to estimate wind speed from the
windsock.

[Roy Smith]

In article >,
"Bob Chilcoat" > wrote:

> I suspect that it comes from the days of sailing ships. All of your course
> decisions are based on the direction of the wind. Tacking, running,
> reaching, etc. are all referred to the current wind direction. I'm not sure
> I fully understand why FROM was chosen as the convention, but when you're
> sailing, you tend to keep the wind in your face unless you're running.

Even more so than today, the old fashioned sailing ships never had the wind
in their face. I sail a J/24, which is a fairly modern design racing boat.
With everything set up right, new sails, and flat water, I can get within
about 35 degrees of the wind. The old square riggers were doing well if
they could get any closer than 60.

This, BTW, is why a toilet on a boat is called the head. On a vessel that
spends most of its time with the wind behind it, you put the toilets up on
the very front (i.e. the head of the boat) for odor control. Even sailors
know not to **** into the wind. It also happens to be the part of the boat
that gets the most water sprayed on it, which is wet and cold for the
users, but does make the apparatus somewhat self-cleaning.

[Chris W]

JohnH wrote:

>Why is that?
>
>
Just guessing here because I'm to lazy right now to think about it, but
could it be that the math to calculate heading corrections is easier
that way?

--
Chris W
KE5GIX

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
One stop wish list for any gift,
from anywhere, for any occasion!
http://thewishzone.com

[Larry Dighera]

On 5 Jan 2006 10:01:48 -0800, "Tony" > wrote in
. com>::

>Make the arrowhead really big and mount the thing by the tail.
>
>Tie a piece of string on a stick and see which way it points.

I know how to do it. I just wanted to see if Jose did.

[Larry Dighera]

On Thu, 05 Jan 2006 22:44:35 GMT, "Steven P. McNicoll"
> wrote in
et>::

>
>"Larry Dighera" > wrote in message
...
>>
>> How would you do that?
>>
>
>The shape doesn't matter. All that's required is greater surface area on
>the downwind side of the pivot point.
>

So the placement of the pivot point is immaterial?

[Jose]

> I know how to do it. I just wanted to see if Jose did.

Yes, I know how to do it. Do you really want to hear the same thing out
of even more posters?

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Steven P. McNicoll]

"Larry Dighera" > wrote in message
...
>
> So the placement of the pivot point is immaterial?
>

Well, where the pivot point is placed would determine which side of the
pivot point had the greater surface area. It all depends on your point of
view. Put the pivot point through the feathers and the arrow will "fly"
backward.

[alexy]

"Steven P. McNicoll" > wrote:

>
>"Larry Dighera" > wrote in message
...
>>
>> So the placement of the pivot point is immaterial?
>>
>
>Well, where the pivot point is placed would determine which side of the
>pivot point had the greater surface area. It all depends on your point of
>view. Put the pivot point through the feathers and the arrow will "fly"
>backward.

I think Larry got you on this one. It is not which side of the pivot
has the greatest area, but which side has the greatest "area-arm".
Think W&B. A weather vane consisting of an infinitely thin rod with a
20 sq inch arrow 1 inch from the pivot and a 3 sq inch tailfeater 10
inches from the pivot will point into the wind.

--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

[Larry Dighera]

On Fri, 06 Jan 2006 02:15:53 GMT, "Steven P. McNicoll"
> wrote in
et>::

>
>"Larry Dighera" > wrote in message
...
>>
>> So the placement of the pivot point is immaterial?
>>
>
>Well, where the pivot point is placed would determine
>which side of the pivot point had the greater surface area.

I would think placement of the pivot point would determine the
arm/moment of the moveable vane. Either end could have greater surface
area than the other, but the end of the vane with greatest moment
(surface area * arm) will trail in the breeze.

[Cub Driver]

On Thu, 05 Jan 2006 16:56:30 GMT, Jose >
wrote:

> When wind is =going= to New Jersey,
>it's their problem. :)

Absolutely.


-- all the best, Dan Ford

email: usenet AT danford DOT net

Warbird's Forum: www.warbirdforum.com
Piper Cub Forum: www.pipercubforum.com
In Search of Lost Time: www.readingproust.com

[Cub Driver]

On Thu, 05 Jan 2006 17:49:51 GMT, Jose >
wrote:

>One could easily design a vane that worked the other way.

But they didn't. All weather vanes point into the wind. So those New
Hampshire farmers must have been onto something, since their cast-iron
horses, carriages, sailboats, kiddies etc all point in the direction I
should land the Cub.


-- all the best, Dan Ford

email: usenet AT danford DOT net

Warbird's Forum: www.warbirdforum.com
Piper Cub Forum: www.pipercubforum.com
In Search of Lost Time: www.readingproust.com

[Steven P. McNicoll]

"alexy" > wrote in message
...
>
> I think Larry got you on this one. It is not which side of the pivot
> has the greatest area, but which side has the greatest "area-arm".
> Think W&B. A weather vane consisting of an infinitely thin rod with a
> 20 sq inch arrow 1 inch from the pivot and a 3 sq inch tailfeater 10
> inches from the pivot will point into the wind.
>

Of course, I was just keeping the explanation as simple as possible for
Larry.

[Steven P. McNicoll]

"Larry Dighera" > wrote in message
...
>
> I would think placement of the pivot point would determine the
> arm/moment of the moveable vane. Either end could have greater surface
> area than the other, but the end of the vane with greatest moment
> (surface area * arm) will trail in the breeze.
>

I didn't think you could understand an explanation using those terms.

[Larry Dighera]

On Fri, 06 Jan 2006 12:21:16 GMT, "Steven P. McNicoll"
> wrote in
et>::

>
>"Larry Dighera" > wrote in message
...
>>
>> I would think placement of the pivot point would determine the
>> arm/moment of the moveable vane. Either end could have greater surface
>> area than the other, but the end of the vane with greatest moment
>> (surface area * arm) will trail in the breeze.
>>
>
>I didn't think you could understand an explanation using those terms.
>

Why not?

Do you find the correct explanation difficult to comprehend?

[Steven P. McNicoll]

"Larry Dighera" > wrote in message
...
>
> Why not?
>

Because based on the level of intelligence you've displayed in these forums
I thought it was likely beyond your ability to understand.


>
> Do you find the correct explanation difficult to comprehend?
>

Nope. It was your ability to comprehend that was of concern.

[Larry Dighera]

On Fri, 06 Jan 2006 13:10:40 GMT, "Steven P. McNicoll"
> wrote in
et>::

>
>"Larry Dighera" > wrote in message
...
>>
>> Why not?
>>
>
>Because based on the level of intelligence you've displayed in these forums
>I thought it was likely beyond your ability to understand.
>
>
>>
>> Do you find the correct explanation difficult to comprehend?
>>
>
>Nope. It was your ability to comprehend that was of concern.
>

Your feeble attempt to cover your ignorance reeks of the same arrogant
transparent paltering of the current sitting President.

Have you ever considered running for office? :-)

[Steven P. McNicoll]

"Larry Dighera" > wrote in message
...
>
> Your feeble attempt to cover your ignorance reeks of the same arrogant
> transparent paltering of the current sitting President.
>

My ignorance? It was you that asked how one would design a weather vane
that worked the other way.

[Larry Dighera]

On Fri, 06 Jan 2006 13:46:34 GMT, "Steven P. McNicoll"
> wrote in
et>::

>
>"Larry Dighera" > wrote in message
...
>>
>> Your feeble attempt to cover your ignorance reeks of the same arrogant
>> transparent paltering of the current sitting President.
>>
>
>My ignorance? It was you that asked how one would design a weather vane
>that worked the other way.

Actually, I asked Jose how *he* would design it.

And now you're implying, that all who ask questions are ignorant. What
of the professor who issues examination questions to his students?
Would you classify him as ignorant also?

Give it up, my friend. You're pathetic cover-up attempt is beneath
someone of your stature who has the lives of thousands of airline
travelers in his hands daily. It only serves to portray your psyche
as so fragile, that it is incapable of withstanding a single insult.

Rather, be a man; admit your lapse. It only proves you're human after
all. No one is infallible; certainly not you nor I.

[JohnH]

>> One could easily design a vane that worked the other way.
>
> But they didn't. All weather vanes point into the wind. So those New
> Hampshire farmers must have been onto something, since their cast-iron
> horses, carriages, sailboats, kiddies etc all point in the direction I
> should land the Cub.

Then why don't airports use weathervanes instead of windsocks? ;)

[Tony]

You disturbed a large number of electrons when you posted

"Then why don't airports use weathervanes instead of windsocks? ;)"

but we think you know weathervanes are telling us where the last wind
came from, and windsocks give us some information as to how hard it's
blowing at the moment.

Flags work well at doing that, too but come to think of it, I'd rather
have a windsock on the flagstick of my golfcourse than a flag.

(and several more on high poles about a 100 yards out, although that
would remove still another excuse for for bad golf shots.)

[Peter R.]

JohnH > wrote:

> Then why don't airports use weathervanes instead of windsocks? ;)

Wouldn't a wind tee be considered a weathervane?

--
Peter

[Steven P. McNicoll]

"JohnH" > wrote in message
...
>
> Then why don't airports use weathervanes instead of windsocks? ;)
>

Windsocks are a bit more useful to a pilot, they provide an indication of
wind direction and speed. Weathervanes provide only an indication of wind
direction.

[Roy Smith]

In article et>,
"Steven P. McNicoll" > wrote:

> "JohnH" > wrote in message
> ...
> >
> > Then why don't airports use weathervanes instead of windsocks? ;)
> >
>
> Windsocks are a bit more useful to a pilot, they provide an indication of
> wind direction and speed. Weathervanes provide only an indication of wind
> direction.

I used to have a weathervane in the shape of a duck with wings that spun
around. You could get a good feel for how fast the wind was blowing by how
fast the wings were spinning around.

One day, after a storm, I discovered that the spinning wings could also be
used to estimate peak gust strength by their absence the next day.

[Jose]

> Actually, I asked Jose how *he* would design it.

Just wondering why you suspect I couldn't. Lots of people think I'm
dumb, some with reason. But the reasons are sometimes amusing.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Larry Dighera]

On Fri, 06 Jan 2006 16:16:51 GMT, Jose >
wrote in >::

>> Actually, I asked Jose how *he* would design it.
>
>Just wondering why you suspect I couldn't.

Oh I had little doubt you would be capable of designing it. I just
wanted to view your effort.

[Capt. Geoffrey Thorpe]

"JohnH" > wrote in message
...
>
>>> One could easily design a vane that worked the other way.
>>
>> But they didn't. All weather vanes point into the wind. So those New
>> Hampshire farmers must have been onto something, since their cast-iron
>> horses, carriages, sailboats, kiddies etc all point in the direction I
>> should land the Cub.
>
> Then why don't airports use weathervanes instead of windsocks? ;)

Some do.

--
Geoff
the sea hawk at wow way d0t com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

[Jose]

> Oh I had little doubt you would be capable of designing it. I just
> wanted to view your effort.

Are my efforts more amusing than most? I'd've done it but others beat
me to the punch.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Larry Dighera]

On Sat, 07 Jan 2006 04:46:01 GMT, Jose >
wrote in >::

>Are my efforts more amusing than most?

I guess we'll never know.

[Jose]

>>Are my efforts more amusing than most?
>
> I guess we'll never know.

Surely you had a prior opinion, else you would not be wondering "just
how I would do it". For the record, I'd simply suggest removing the
tail feathers and replacing it with a weight to keep the thing in
balance. Assuming it had a significant arrow point (some do) that
should be sufficient. Otherwise reshape the tail into an arrow point -
the thing would be oriented in the same direction but the shape would
now point the other way.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Larry Dighera]

On Sat, 07 Jan 2006 16:07:49 GMT, Jose >
wrote in >::

>>>Are my efforts more amusing than most?
>>
>> I guess we'll never know.
>
>Surely you had a prior opinion, else you would not be wondering "just
>how I would do it".

You made an assertion, and I wanted to see what *you* had in mind. I
had no preconceived idea of what your answer might be.

Look how "interesting" Mr. McNicol's suggestion turned out. :-)

>For the record, I'd simply suggest removing the
>tail feathers and replacing it [sic] with a weight to keep the thing in
>balance. Assuming it had a significant arrow point (some do) that
>should be sufficient.

See there. That's a unique suggestion. Of course it's not correct
for *all* instances, but as you state, it should work for most.

>Otherwise reshape the tail into an arrow point -
>the thing would be oriented in the same direction but the shape would
>now point the other way.

I presume this suggestion is dependent on the removal of the arrowhead
as you mentioned earlier. (Correct me if I've inferred this wrong,
but you are suggesting that both the arrowhead and tail feathers be
removed, and the arrowhead be reattached at the former location of the
tail feathers with its point toward the end of the arm, and the pivot
point unaltered.) If so, and the weather vane worked normally before
it was modified, it should function as you expect.

As I stated earlier, the end of the weather vane that points into the
wind (or with the wind) is dependent on the placement of the pivot
point (which governs the arm length) and the side area of each portion
(arm) of the vane on either side of the pivot point. It's similar to
what we all do when calculating weight and balance. In this case, the
length of each arm is multiplied by its side area (including any
"feathers" or "arrowhead" and the area of the arm itself). The end
with the larger moment forces its other end to point into the wind
when placed in the airstream. At least, that's the way I see it.

The physics involved are so intuitively trivial, that the subject is
hardly worth the discussion.

[Jose]

> The physics involved are so intuitively trivial, that the subject is
> hardly worth the discussion.

....which is why I am puzzled by your specific interest in my response.
But hey, this is Usenet. :)

> I presume this [second] suggestion is dependent on the removal of the arrowhead
> as you mentioned earlier.

No, it's predicated on "otherwise" - the case where there was not a
significant arrow point, and the only significant area exposed to the
wind is the tail.

> (Correct me if I've inferred this wrong,
> but you are suggesting that both the arrowhead and tail feathers be
> removed, and the arrowhead be reattached at the former location of the
> tail feathers with its point toward the end of the arm, and the pivot
> point unaltered.)

No, just make the tail look like an arrow (pointing away from the pivot)
and you're done. No reattachment needed.

However, you do bring to mind a third way - a sort of stealth
weathervane. Take the tail =and= the head off, and reattach both them
in the opposite places (put the tail where the head was, and the head
where the tail was) and opposite directions (it would still look like an
arrow rather than something from Salvador Dali). The weathervane will
now point in the opposite direction than it did before, but since you
reversed the window dressing, it will look (to outsiders) as if nothing
had changed. Those who do not know of your secret modification will
simply see what looks like a normal weathervane, pointing into the wind.
But =you= (and anyone else you've clued in on your secret) will know
that the support beam is actually pointing in the opposite direction -
in the direction the wind is going!

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

[Nils Rostedt]

"Bob Chilcoat" wrote
>I suspect that it comes from the days of sailing ships. All of your course
>decisions are based on the direction of the wind. Tacking, running,
>reaching, etc. are all referred to the current wind direction. I'm not
>sure I fully understand why FROM was chosen as the convention, but when
>you're sailing, you tend to keep the wind in your face unless you're
>running.
>

I'd go back even further in time. Even before the age of ships, the
direction the wind comes FROM was the most interesting, as looking in that
direction could tell how the weather will change (well, fronts are
different, but they are a later invention). Later, when man learned to build
boats, looking INTO the wind was (and is) the best way to see how hard it
blows at sea, i.e. is it safe to leave the shore. It's easy to imagine that
the wind god is in that direction - better keep attention to him!

Just my $0.02 ;-)