Talk:Trewartha climate classification

Then what happened?
The article is partly written in the past tense, "it was considered", "were seen", etc., which suggests that this classification is no longer in use. But the article doesn't describe why that is the case. It lists several problems with the Köppen system that were solved by the Trewartha system. So why do so many wikipedia articles give classifications in the Köppen system? 2602:306:CEAE:E60:6C18:646D:2ABF:EF73 (talk) 01:27, 17 May 2016 (UTC)

Issues with Trewartha
I'm having trouble tracking down classification guidelines for Trewartha that make sense. I've been making climate maps with the Koeppen scheme, and was attempting to do a Trewartha map of the US. I was using the guidelines from the following paper: http://www.int-res.com/articles/cr_oa/c059p001.pdf

I hit trouble for Cs, their dry-summer subtropical/Mediterranean climate.

It outlines that type as having:
 * A winter half year with more than 3 times the precipitation of the summer half year.
 * Less than 30 mm precipitation in driest summer month
 * Less than 890 mm precipitation annually

In contrast, Cf is classified as: Not meeting the guidelines of Cs or Cw (there is no Cw in the U.S.), and have no month with less than <30 mm.

My issue is that that leaves out a lot of land that doesn't meet the guidelines for Cs, Cw, or Cf. There's a significant amount of land in California that meets the criteria for C (>8 months with mean temp >10C), has a driest summer month <30 mm, but has >890 mm annual precipitation. Currently, I'm unable to classify large stretches of land in northern California that are essentially category-less. Not sure why Cf has the 'no month <30 mm.' restriction.

Does anyone have access to the 1980 work by Trewartha and Horn who can elaborate? I don't currently, and would appreciate any clarification. Redtitan (talk) 02:08, 22 September 2016 (UTC)


 * I tracked down the original work. Think I'll make some updates to this article, as well as include some criticisms of the scheme. Redtitan (talk) 16:54, 18 October 2016 (UTC)

Trewartha is not without weaknesses. Amarillo, Texas, for example, is Do under this system but the difference between the warmest and coolest months is pretty sizable. People from Amarillo would laugh if one were to tell them that their climate is oceanic. Heff01 (talk) 01:03, 5 August 2019 (UTC)

Actually, Amarillo is a short distance west of the Do zone and has a semi-arid climate. It has seven months >10° C. Heff01 (talk) 08:02, 19 September 2020 (UTC)

Accuracy of Classifications
I think it is extremely difficult to categorize the World's Climates, and be 100% accurate, but I think there are some glaring inaccuracies. I doubt that anyone who lives in NC or Va would compare our Winters to any part of Florida in the vast majority of years, yet we are all in the same "Subtropical" Climate, although NC/Va is sharply colder. This is just one example. The categories under both Koppen and Trewartha are just too broad to be truly meaningful. — Preceding unsigned comment added by 152.28.195.227 (talk) 18:59, 18 February 2019 (UTC)

As a climate researcher...the above concept is 100% logical and the climate data backs it up. Yet. the Koppen climate classification groups an even LARGER area of the eastern USA into a single zone. A winter in Jacksonville is far different from one in New York City or Boston. yet koppen grouped them all into the same Cfa zone. At least Trewartha tried to logically separate climates that have modest snow in winter (like NYC) and climates that are 60 F in winter like north Florida. Yet, someone has just changed the "subtropical humid " climate to include NYC and Orlando into the SAME climate zone. Why? Marketing maybe. That's the trouble with wikipedia...it is now nothing more than a biased or market based source. I can't autosign like you above because i don't know how. — Preceding unsigned comment added by 2601:188:180:4D86:F857:A28:41D2:F34C (talk) 19:27, 9 August 2019 (UTC)


 * Are you referring to recent edit disputes on Humid subtropical climate? For better or worse, Wikipedia has typically heavily used the Köppen system, under which that change is accurate. I do notice at least one spot where the article already specifies "Under Köppen's climate classification", so that the reader should know that that information depends on the classification system.


 * Wikipedia certainly has problems with paid advocacy, but this seems more like a garden-variety content dispute to me. Feel free to start a discussion on Talk:Humid subtropical climate if you'd like to argue that that article should be written more from a Trewartha perspective (which wouldn't be unreasonable, if Köppen never used the term "humid subtropical"). WP:CONSENSUS may currently lean towards Köppen, but that's what talk pages are for: discussing and possibly changing consensus.


 * Also, adding  will sign your comment. Note that it doesn't add a space on its own. Benny White (talk) 20:31, 9 August 2019 (UTC)


 * This is just my WP:OR but I'd say as Trewartha and Köppen both have fairly few climate zones, these problems are going to recur around the world in both systems. Trewartha may have been fine tuned for USA but that doesn't mean it won't e.g. categorise half the Europe from London and Sarajevo as "oceanic". The reason Köppen is more widespread is probably because it's more present in reliable sources. It seems to me that Trewartha sees little use outside USA.  Daß &thinsp;  Wölf  00:34, 10 August 2019 (UTC)


 * Any attempt to categorize the world's climates into a fixed number of "types" will face severe limitations. Yes, Koppen put NYC and DC in the same climate type as Orlando or New Orleans. But Trewartha's "fix" put NYC and DC in the same climate type as Vancouver, Canada; Edinburgh, Scotland; Bergen, Norway; and even the southernmost reaches of Alaska. This is obviously far more absurd; in most of these locations July is colder than a New York October. But Trewartha specifically set the cutoff for Cfa at 5 months below 10 Celsius, and it just so happens in the fifth month below 10C (November) NYC averages 9.5C and DC averages 9.9C. Bend over backwards to fix the problem of the Mid-Atlantic coast having the same climate as most of the Southeast, create a new problem where it has the same climate type as parts of Alaska. You can't win. In my view, Koppen is the most simple, straightforward and reasonable, because any attempts to correct it just create more complexity and more errors. NYC/DC climate is obviously much closer to the southeastern US than to northwestern Europe or bloody Alaska. 96.242.144.8 (talk) 17:36, 7 February 2022 (UTC)

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