# Talk:Wind shear

WikiProject Meteorology (Rated GA-class, Mid-importance)
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WikiProject Aviation / Gliding (Rated GA-class)
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WikiProject Physics / Fluid Dynamics  (Rated GA-class, Low-importance)
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WikiProject Tropical cyclones (Rated GA-class, Mid-importance)
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Wind shear has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
Date Process Result
November 2, 2006 Good article nominee Not listed
December 16, 2007 Good article nominee Listed
Current status: Good article

## Initial efforts to organize article

Added references and a couple sections regarding wind shear's effects on thunderstorm formation and tropical cyclones. Thegreatdr 16:13, 21 October 2006 (UTC)

I think the article is good enough for B class. If not, useful comments for it reaching B class would be appreciated. Thegreatdr 19:56, 22 October 2006 (UTC)
Very good article! I'm going to send it to WP:GAN. -Runningonbrains 12:18, 25 October 2006 (UTC)

## Failed GA

I'm afraid that the writing in this article isn't really up to GA standard. The second paragraph in the lead is a very blank summary of the main headlines, with no variation in sentence structure and no common theme tying the statements together. The section on when and where wind shear is observed really ought to be in prose form rather than in bullet points. And the final three sections have only two sentences each, which really leads to the suspicion that they could do with some expansion.

Please feel free to resubmit once these points have been addressed. MLilburne 11:39, 2 November 2006 (UTC)

## Merger?

Should this article be merged with wind gradient? It looks like the articles define it identically. Thegreatdr 14:47, 28 November 2006 (UTC)

Either they should remain separate (and expanded), or gradient should be merged here. Wind shear is the chief term and of multiple usage in meteorology. The Glossary of Meteorology (AMS, 2001) doesn't list wind gradient but defines wind shear as follows:
wind shear—The local variation of the wind vector or any of its components in a given direction.
The vertical shear can be expressed in terms of height ∂V/∂z or of pressure ∂V/∂p as the vertical coordinate. If the wind is geostrophic, the vertical shear is given by the thermal wind equation. The wind shear at a point is said to be cyclonic or anticyclonic according to whether the sense of rotation from the wind vector to the shear vector at that point is cyclonic or anticyclonic.
Evolauxia 19:38, 28 November 2006 (UTC)
I agree that the other article would be merged into this one, if merger is deemed acceptable. I can't imagine both articles being expanded. It would be like having two articles, with one named thermal wind and another called wind shear. Same deal. Thegreatdr 23:12, 28 November 2006 (UTC)
Oops. There is also a thermal wind article! This could be merged in as well, since thermal wind is another term used for vertical wind shear. Thegreatdr 23:13, 28 November 2006 (UTC)
Merge and add redirects. One concise and thorough article is better than many short ones. --Patar knight 21:41, 27 May 2007 (UTC)

## downburst

The downburst definition doesn't seem to match the link to the downburst article. --Gbleem 11:05, 24 May 2007 (UTC)

## Cleanup tag

I started cleaning up this article, and the more I did, the more work I found. First, the lede does not fully define and develop the subject. The article also needs further development, as it focuses heavily on aviation aspects, and does not cover other areas much. Also, it fails to compare and contrast high vs. low level and vertical vs. horizontal wind shear. More research and references are also needed. Dhaluza 11:01, 29 May 2007 (UTC)

The lead has been completely reorganized per the new information included from wind gradient and the cleanup tag has been removed. Thegreatdr 13:51, 3 June 2007 (UTC)

This article still contains obvious grammatical errors. —Preceding unsigned comment added by Cemcclelland (talkcontribs) 21:17, 23 January 2008 (UTC)

We are woring cross purposes now, because I am still working on the content at wind gradient, and the differences will be lost. Please remove the bulk of the that content now, and reorganize and expand this article first. In particular, it needs to be expanded to cover the more general cases first. Then we can see where this fits. For example you have lumped the effects on flight together, but there are many different ways wind shear affects aviation, e.g. microbursts, lee waves, wind gradient, and they are completely different cause and effects. Dhaluza 15:00, 3 June 2007 (UTC)

See the comment on the wind gradient article. I could live with the differentiation I spelled out on that talk page, and it would appear to fall in line with the gradient and shear articles within wikipedia. This is my second attempt to compromise with you on this topic which would allow for two articles rather than one. Right now, scholarly references overwhelmingly favor wind shear over wind gradient otherwise, per a check made by someone else. I just don't see the differences between the two topics, since both emphasize changes of winds on the microscale (particularly in the vertical) and their effects. Clearly differentiate wind gradient from this article, somehow, and there wouldn't be this problem. Thegreatdr 16:25, 3 June 2007 (UTC)
Also see the reply at Talk:wind gradient. As far as references, they are cited in the wind gradient article, and you can check them at Google or Amazon, and all appear to be reliable. This is not necessarily a case of either/or or right/wrong. I would expect that since wind gradient generally refers to a special case, there would be less reference material on it, but there is more than enough to support that article.
As for this article, dropping in the bulk of the content from there has taken this article from needs cleanup, to needs cleanup^2. My strong suggestion is to take most of it back out, and clean this up by addressing the issues already identified above. I would recommend organizing this article to fully develop high-level vs. low-level and vertical vs. horizontal wind shear first. I think once that is done, it will make sense to take the special case of "low-level vertical shear of horizontal wind with a logarithmic velocity profile" (whatever it is called), and paraphrase the content in the wind gradient article with a {{main}} link to the other article. Dhaluza 16:56, 3 June 2007 (UTC)
Horizontal wind shear is talked about within the weather fronts line, and is talked about within the weather fronts article. There is wind shear near the jet stream which hasn't been discussed...I can add that in easy enough. Most of the important effects of wind shear lie near the top of the planetary boundary layer, or just above vertical slices of frontal zones/outflow boundaries/squall lines and on the lower periphery of the low level jet. Ekman layer and Ekman spiral (which have merge tags) and planetary boundary layer already discuss what you appear to be proposing for wind gradient. If that is what you are proposing, move the information you're developing over to planetary boundary layer or ekman layer. It would still call for wind gradient to become a redirect. Thegreatdr 17:07, 3 June 2007 (UTC)
Yes, most of the important meteorological wind shear effects happen above the surface, and these are not well developed yet in this article. It also does not address horizontal shear of horizontal wind vs. vertical shear of horizontal wind, or vertical shears in detail. For example, the word "convergence" does not even appear in this article, and there is no link to Convergence zone or shear line. Dhaluza 17:33, 3 June 2007 (UTC)
Wikilinks are now added for convergence zone and shear line. Thegreatdr 02:37, 9 October 2007 (UTC)

SUGGESTION: Another cause of windshear is a CONVERGENCE ZONE, like a seabreaze front —Preceding unsigned comment added by 68.71.79.65 (talk) 20:04, 16 February 2009 (UTC)

## Nominated again for GA

Now that it appears that wind gradient has little chance of being merged in with this article, and the details in the lead fit the article below, I've nominated it anew for GA. Thegreatdr 22:19, 3 October 2007 (UTC)

Good job cleaning the article up and recasting it in summary style. I would suggest you address the two specific suggestions above to cover convergence zone and shear line (meterology) as well. Also some additional references would be good, for example the lead as well as the "Definition", "Weather fronts" and "Thermal wind" sections have no inline cites. Good luck with the GA nom. Dhaluza 14:57, 8 October 2007 (UTC)
Added inline references to definition, weather fronts, and thermal wind sections. Thegreatdr 04:12, 9 October 2007 (UTC)

### GAC

#### On Hold

This article passes a lot of criteria, and based on the references, it appears to be correct too. However:

1. In my opinion the article is not layman-friendly. It relies too much on jargon much of which needs to be explained to consider this article accessible and well-written.
2.  Done At the time I reviewed this at the start of the month, at least two paragraphs were not referenced. (If a reference convers all the text in a section, either refer to it multiple times or put it at the far bottom).
3. I also think that the lead should be referenced for people who read that as a summary and go no further as per Wikipedia:Summary style.
5.  Done In the "effects on tropical cyclones"-section it says "in the direction of the shear". If wind shear is a difference windspeed or direction - let's say it's strong west 5 here and weak north 1 a couple of miles south - then what is the direction of the shear? I think that's impossible to say without laying down the rules or clarifying what you have already. - Mgm|(talk) 21:59, 13 November 2007 (UTC)
Have rewritten the article to be more easily understood. Removed the duplicate links from the see also section as well. Also added links to paragraphs where links were missing. Thegreatdr (talk) 15:25, 25 November 2007 (UTC)

#### Second opinion

• The "effects on tropical cyclones"-section is still too complicated. I've asked for a second opinion on the word usage. -- Mgm|(talk) 23:01, 30 November 2007 (UTC)
• It's down to two lines. I can't imagine stating it simpler, unfortunately. Does anyone have an idea of how it can be reworded to be more understandable? Thegreatdr 08:38, 2 December 2007 (UTC)
• I reworked it to be more lay friendly. Dhaluza 15:19, 2 December 2007 (UTC)
• The first line of the article says that Wind shear is sometimes called wind gradient, yet wind gradient has its own article, and appears to be a separate but related phenomenon? The sections in this article on flight and architecture use "wind gradient". Perhaps the "definition" section could explain what the difference is, and the flight section state why gradient is used, not shear? Jonathan Oldenbuck 11:35, 3 December 2007 (UTC)
• I wish I understood the difference completely. According to Dhaluza, it appears wind gradient is used in some circles to talk about frictional effects within the planetary boundary layer, close to the ground (very low level wind shear). We would need a reference explaining what the definition of wind gradient is before including it in this or any article. I changed the gradient wording to low level wind shear to avoid the issue. Thegreatdr (talk) 04:22, 5 December 2007 (UTC)
• Outside meteorology, wind gradient is commonly used to refer to frictional (or, more technically, drag) effects from surface interaction with the wind. It is a special case of vertical shear of horizontal wind at the bottom of the atmosphere. The separate article on wind shear is intended to deal with this specific case and its implications, and this article should only address wind gradient in summary style leaving the main points to the dedicated article. This article still contains much duplicated material copied from that article. Dhaluza (talk) 14:49, 22 December 2007 (UTC)

You asked for someone who is not an expert in the field - you got one. :-)

• This sentence: "The meteorological concept of thermal wind deals with how differences in wind with height are dependent on horizontal temperature differences." is convoluted and confusing.
• Tried to simplify the beginning of the sentence...but cannot think of a way of simplying section after "deals with" Thegreatdr (talk) 20:05, 12 December 2007 (UTC)
•  Done The thermal wind equation section : "Since f is small or zero there" By f do you mean ${\displaystyle f}$? it's not immediately obvious to a non-expert that these are the same.
•  DoneThe main article notes are overused. These are supposed to point to an article that has more detail on the topic of the paragraph than can fit in this section. "When Wikipedia articles become too large, subarticles are usually created. This template is used to mark the section of the "Main" article that was separated to add a link to the new article." That's not what they're being used for.
•  Done Sailing, for example, has darn little on wind shear and sailing - I can't find the term mentioned in the article at all. It should be at most a See also, but frankly, since it has so little relevant information, I'd leave it out altogether - the links around the word sailboats, sail twist, etc., should more than suffice. Same for several others, I'm sure.
•  Done Wind engineering is a field of engineering ... Wind Engineering draws upon meteorology ... - decide whether or not to capitalize the E and stick to it.
• All that said, this is a good article, and I mean it in the formal sense. These are just minor tweaks and can be easily fixed. I haven't reviewed many GAs (yet!), but I think it's ready for promotion. Beautiful photos, excellent references, well organized, and probably as simple as it can be without being actually incorrect. --AnonEMouse (squeak) 15:40, 12 December 2007 (UTC)
• I'd be willing to promote it. If it were going for FA, that might require a bit more scrutiny to see if it's "perfect", but it's fairly clearly "good", even Good. Mgm, disagree? --AnonEMouse (squeak) 20:14, 12 December 2007 (UTC)
• I would like to add some comments for the GA review as a gliding instructor and private pilot if I may:
•  DoneThe definition para could be better, I looked for an official definition but could not find one. A speed of 30 knots is mentioned, the FAA in this 64 page circular FAA windshear advisory circular states that 40 to 50 knots would be significant for a large airliner. This speed would be much less for light aircraft.
•  DoneAgain in the definition para there are mixed units, metres per second is given for horizontal velocities but metres per minute are given for vertical velocities, this should also be metres per second.
• Wind gradient/wind shear seems to be an insolvable problem. Glider pilots in the UK would know the loss of airspeed on approach to be caused by the wind gradient. Powered flying training books I have call it wind shear.
•  DoneThe gliding paragraph is very good, I would note that ground launch is more commonly known as a winch launch or wire launch. The term ground launch is a redirect to the gliding article where the launches are described as winch/wire.
• Will try to find an appropriate reference for this. Do you know any offhand? Thegreatdr (talk) 04:03, 16 December 2007 (UTC)
• Actually ground launch is the correct generic term which covers both winch launch and auto tow. Dhaluza (talk) 14:49, 22 December 2007 (UTC)
•  DoneIt could be mentioned in the dynamic soaring section that this technique has been recently discovered by slope soaring aeromodellers and allows their model gliders to reach extremely high speeds.
• Added this information into the dynamic soaring subarticle. Thegreatdr (talk) 04:07, 16 December 2007 (UTC)

I thought I should help as I have just nominated an article for GA myself, I think this article is nearly there, cheers. Nimbus227 (talk) 18:09, 14 December 2007 (UTC)

## GA

GAC has passed on this article. Congrats. Juliancolton (talk) 14:12, 24 December 2007 (UTC)

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