Talk:Wind

From Wikipedia, the free encyclopedia

You have new messages (last change).
 This article related to meteorology and/or specific weather events is part of WikiProject Meteorology and Weather Events, an attempt to standardize and improve all articles related to weather or meteorology. You can help! Visit the project page or discuss an article at its talk page.
B This article has been rated as B-Class on the assessment scale.
Top This article has been rated as Top-importance within WikiProject Meteorology.
Wind is included in the 2006 Wikipedia CD Selection, or is a candidate for inclusion in the next version. Please maintain high quality standards and, if possible, stick to GFDL-compatible images.

Would it be appropriate to put Kamikaze (lit. Devine Wind) on this page? Kazuhite 08:07, 1 March 2006 (UTC)


Some one should write an article about WIND the AM 560 radio station in Chicago.


What is the difference between the versions of September 1 and August 6? RickK 02:35, 2 Sep 2003 (UTC)

I appreciate the effort made by the writer of the original page, but there were many problems with it. I have reorganized it to follow current terms and practices in meteorology/climatology, and have extended it considerably. Denni 19:05, 2004 Jan 18 (UTC)


(William M. Connolley 16:35, 2004 Mar 10 (UTC)) I've made a load of minor hacks (and rewritten the intro). I completely removed:

In certain circumstances, the Coriolis force acting on moving air may be almost or entirely overwhelmed by the centripetal force. One such circumstance is at the equator, where, for all practical purposes, the Coriolis force is nonexistent. Such a wind is said to be cyclostrophic, and is characterized by rapid rotation over a relatively small area. Hurricanes, tornadoes, and typhoons are examples of this type of wind.

because its badly flawed. There are no hurricanes on the equator. The orographic wind bit is dodgy. I didn't believe the origin of the phrase "trade wind".

While I cannot lay any right to this article, I nonetheless take some pride in it.

(William M. Connolley 22:39, 2004 Mar 11 (UTC)) Thats what I thought, so I've done my best to inform you rather than slip the changes in...

Many of the changes you made were good ones, especially in those cases, such as the intro, where you added to existing material. However, I am a little concerned that material has simply been deleted without correction or modification - paragraphs on the cyclostrophic and geostrophic winds (while you quite correctly say that hurricanes do not form on the equator, they have been known to drift across it).

(William M. Connolley 22:39, 2004 Mar 11 (UTC)) I'm fairly sure that hurricanes (or as wikipedia calls them, trop cyclones) depend crucially on coriolis to form and maintain. I did check on some hurricane track pages to confirm this... I can't find the page I used now. But look at http://www.wunderground.com/hurricane/at2003.asp or 2002 or 2001. No tracks within 10 deg of the equator. If hurricanes do occaisionally cross the equator, I think this is the exception not norm.

I would also expect that you would agree that disbelief is not a vaid reason on its own to change a point. "The wind blows trade," is legit - "trade" is an Old English word for path or track, which makes sense, because that is exactly how trade was (and still is) carried out.

I was unsure of that. I see you've restored it - fair enough. To me, "trade wind" means the wind used for trading ships, and needs no further explanation. But OK.


What is it you find "dodgy" about orographic wind? As I have indicated, it is not a formally-employed meteorological term. It nonetheless describes a real meteorological event, and I can vouch for that, living, as I do, less than 30 km from the east slope of the Canadian Rockies.

(William M. Connolley 22:39, 2004 Mar 11 (UTC)) I'm embarrassed to say I can't remember exactly why. Apologies for needless irritation. Trying to reconstruct, I think my feeling was that an orogrpahic wind often meant a wind affected by local orography - in the sense of being turned perhaps rather than lifted. And it does seem to be a recognised term: see e.g. http://amsglossary.allenpress.com/glossary/browse?s=o&p=15

The Internet is our friend. Doing an advanced search on trade or on geostrophic/cyclostrophic wind will show you that if my facts are incorrect, so are those of meteorology professors. Denni 19:10, 2004 Mar 11 (UTC)

Re cyclostrophic... I felt your para was implying that these winds happened *particularly* over the equator. I plead that others might be similarly mislead. I've restored the para, with the equator bit removed.

I appreciate your reply, William. I'm not interested in any turf war here; this is, after all, a place of collaborative effort. We serve each other best by keeping each other honest. I'd like to keep a dialog going - I'm the first to admit that my knowledge is not complete and so I'm always open to other views. I also hate getting called out (as you might have noted), and therefore make every effort to ensure my facts are correct. Those I am not absolutely certain of, I research until I'm satisfied with their integrity. Still, things slip by; see further on the Talk:Atmospheric circulation page. Denni 18:04, 2004 Mar 12 (UTC)

Contents

[edit] No 'third force' involved in geostrophic flow

The following passage in the article is unintelligable:

In nature, isobars are almost always curved. The result is that a wind moving parallel to the isobars encounters a third force, the centripetal force. This is the force which tends to keep a body in motion moving in the same direction. The effect of this force, though not a force in itself, is called the centrifugal force, and acts to counteract the Coriolis force (coincidentally also the effect of a force rather than a force in itself) and decrease the wind speed. This much more common situation results in what is known as a gradient wind.
In certain circumstances, the Coriolis force acting on moving air may be almost or entirely overwhelmed by the centripetal force. Such a wind is said to be cyclostrophic, and is characterized by rapid rotation over a relatively small area. Hurricanes, tornadoes, and typhoons are examples of this type of wind.

Here is how I understand it.
Winds are categorized as geostrophic if in the dynamics the following two factors are vastly dominant: the pressure gradient force, and the coriolis effect. In the case of northern hemisphere winds circling a low pressure area, the pressure gradient acts in centripetal direction. (I will call the full circle of winds around the low pressure area 'the geostrophic flow') The coriolis effect tends to deflect any flow to the right. When there is no contraction of the geostrophic flow then there is an region of dynamic equilibrium, where the pressure gradient force is enough to maintain the same deflection to the left, but not strong enough to cause contraction of the geostrophic flow.

In regions where there is a surplus of pressure gradient force there will be a surplus of deflection to the left, which is a contraction of the geostrophic flow. This contraction is deflected to the right due to the coriolis effect, increasing the velocity of the wind. At small diameters of the geostrophic flow the coriolis effect becomes negligable, but contraction down a pressure gradient will still increase the angular velocity in the center.

There is no third force!
The coriolis effect deflects all flows to the right, therefore the direction in which it acts varies with the direction of the flow. In the absence of contraction the coriolis effect is what counteracts flow down the pressure gradient. As soon as there is contraction it is deflected to the right. --Cleon Teunissen | Talk 20:05, 13 Mar 2005 (UTC)

(William M. Connolley 13:29, 15 Mar 2005 (UTC)) As I understand it (Holton, An Intro to Dynamic Meteorology) geostrophic approx is pressure-coriolis balance. This can only occur in the real world if the height contours are latitude circles. Gradient approx is flow parallel to the height contours, a balance between coriolis, centrifugal force and pressure gradient. It is usually a better approx to the actual wind than the geostrophic approx.

Another remark: in the case of geostrophic flow, the pressure gradient force can in particular regions be stronger than a centrifugally acting coriolis effect, the strengh of the coriolis effect is proportional to the velocity of the wind, and if there is not enough velocity then that's it. But I think the opposite will occur in very special circumstances only. It is pressure gradient force that starts air moving in the first place, so only input from outside could possibly whip up winds to a velocity where a centrifugally acting coriolis effect is stronger than the pressure gradient force. The engine of the process is the pressure gradient force; when the geostrophic flow loses kinetic energy through friction, the geostrophic flow will contract, releasing energy that is instantly converted to kinetic energy. I learned the use of flow-of-energy to keep track of the causal chain from an article by Anders Persson. A 374 KB article on the coriolis force by Anders Persson
The pressure gradient force and the coriolis effect act in a fundamentally different way. The pressure gradient force is the engine, the coriolis effect converts energy (and friction dissipates the energy). Using the expression 'coriolis force' has the disadvantage of disguising the difference between force and coriolis effect. --Cleon Teunissen | Talk 21:37, 13 Mar 2005 (UTC)

Third remark. In the article it is stated:

This is the force which tends to keep a body in motion moving in the same direction.

In a non-rotating environmont objects will move in a straight line when there is no force being exerted, the well-known inertia. However, the solid Earth plus atmosphere is a rotating environment, and because of that the inertial properties of the air masses of the atmosphere are governed by orbital dynamics, the dynamics of mass orbiting the axis of the Earth. Inertial motion of atmospheric air masses is a curved motion with respect to the coordinate system that is co-rotating with earth. Air masses that do not move are in dynamic equilibrium, but air masses that are in motion curve away to the right (on the northern hemisphere).
So the usual thinking that mass tends to move in straight lines does not apply in the case of atmospheric motions on the rotating Earth.

Geostrophic flow away from a high pressure area is a very interesting situation. Being deflected to the right, and not being free to move outward indefinately, it will start to flow clockwise. The clockwise flow curves to the right, the local direction of inertial motion.
Any flow that rotates clockwise with a period of 12 hours will be entirely inertial motion. A clockwise atmospheric circulation with a period of 12 hours will be stable on its own; any pressure gradient would disrupt it. A clockwise circulation with a period of 12 hours is in dynamic equilibrium with respect to the inertial system it is orbiting in.

[edit] To much explanatory dynamics

(William M. Connolley 13:21, 15 Mar 2005 (UTC)) I reverted CT's changes. Sorry. The reason was that it seemed to be introducing too much explanatory dynamics into a general purpose article. I have cut out the para he didn't like though.

In general there seems to be a confusion here between the actual winds in the world and the various mathematical approximations to the equations. The math approx is dealt with lower down (in Winds that are defined by an equilibrium of physical forces) and that seems to make sense. I don't think the section about "synoptic winds" should be doing this again, but worse... it should be about actual winds.

I also didn't like The primary motion of air is to move from higher to lower pressure. Since there is nothing to stop the air from curving to the right it curves to the right as it moves. This seems too much like the handy-wavy version of the dynamics... it starts to do this, then it does that. Atmos flow is almost always near-balanced. The geostrophic wind page seems better.

OK, to much in-depth in a general purpose article.
When I wrote, 'the primary motion is' I did not mean to imply a sequential ordering, a sequence in time. My intention was to emphasize a direction of energy flow through the system. The pressure gradient as the supplier of the energy of wind, (and friction dissipating energy). Of course, low pressure areas form gradually, so the wind patterns change gradually.
Language is sequential, it's pretty hard to convey the interconnectedness of the dynamics of wind. If only I could use infinitisimals in everyday language... --Cleon Teunissen | Talk 14:24, 15 Mar 2005 (UTC)

[edit] A third force

There is no third force! --Cleon Teunissen | Talk 20:05, 13 Mar 2005 (UTC)

(William M. Connolley 13:29, 15 Mar 2005 (UTC)) As I understand it (Holton, An Intro to Dynamic Meteorology) geostrophic approx is pressure-coriolis balance. This can only occur in the real world if the height contours are latitude circles. Gradient approx is flow parallel to the height contours, a balance between coriolis, centrifugal force and pressure gradient. It is usually a better approx to the actual wind than the geostrophic approx. (William M. Connolley 13:29, 15 Mar 2005 (UTC))

Yes, in the gradient wind approx there are three forces in the equations. At first, I didn't quite see the implications of that.
Gradient wind approx covers both the situations where coriolis effect and centrifugal force act in the same direction, and situations where they act in opposite directions. Of course, coriolis effect and centrifugal effect cannot actually oppose each other since both are manifestation of inertia. If they oppose each other in the calculation, then in the atmosphere there will be either centrifugal force or coriolis force, depending on the direction of the pressure gradient force. more likely depending on magnitude of pressure gradient force and velocity of the wind. --Cleon Teunissen | Talk 20:02, 15 Mar 2005 (UTC)

A special case of gradient wind is inertial wind. In inertial wind there is no force involved. External link: Inertial flow - Balanced flow tutorial by Ryan Turkington On that webpage the period of inertial wind is given: 12 divided by the sine of the angle of the latitude gives the number of hours of the period of rotation. Close to the poles the period is nearly 12 hours. --Cleon Teunissen | Talk 15:33, 15 Mar 2005 (UTC)

[edit] Alize Winds?

Can somebody who knows this weather stuff add some info about Alize winds to this article? I recently went searching for details on what the Alize winds were and found very little information out there.

[edit] Coriolis effect

The article says

In certain circumstances, the Coriolis force acting on moving air may be almost or entirely overwhelmed by the centripetal force. Such a wind is said to be cyclostrophic, and is characterized by rapid rotation over a relatively small area. Hurricanes, tornadoes, and typhoons are examples of this type of wind.

The Coriolis force is not "overwhelmed"! The Coriolis effect can only cause at most one revolution per day. Other things are happening by the time there is rapid rotation. Paul Beardsell 23:58, 23 August 2005 (UTC)


Great page but no mention of wind as an energy/power source . . .

Rossfi 11:48, 30 August 2005 (UTC)

[edit] Vandalism

I'm rather new to Wikipedia, and am not well versed with all the editing "tricks" out there. When I brought up this article, the first line defined wind as "...horizontal movment of air caused by Howard Stern's asshole..." However, when I went to edit the page to correct that line, the vandalism doesn't appear in the editing window. Hope someone smarter than me knows how to correct this. -Dave

[edit] Nice photo of boundary

http://www.kilty.com/contrail.htm

[edit] 1 question

I just have a 1 question. Has there ever been a case where wind moved in a vertical fashion? even for a little while? You know, how wind moves circular like the Earth spinning? Angelofdeath275 19:03, 30 September 2006 (UTC)

Microbursts would be wind moving in a verical fashion. But I am not sure this is what you are looking for.

Convective updrafts are another - but it's not wind except where it has a horizontal speed which can be measured. Crimsone 07:47, 11 December 2006 (UTC)
My word! Picked up as unsigned by a bot before I had chance to notice and sign it! A bit too quick off the mark there I suspect!Crimsone 07:47, 11 December 2006 (UTC)

[edit] "...egg of air"?

"Wind is the rough part of a egg of air..." -- what's an "egg" of air? CSWarren 17:51, 6 February 2007 (UTC)

[edit] Um Help?

What causes Winds? And what are Horse Latitudes? —The preceding unsigned comment was added by 70.245.112.243 (talk) 00:54, 20 March 2007 (UTC).

The fist sentance says: Wind is the ruf horizontal movement. Is is maybe supposed to be rough? not ruf?

Retrieved from "http://en.wikipedia.org../../../w/i/n/Talk%7EWind_c02a.html"