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View Poll Results: Which classification system do you prefer?
Köppen-Geiger 12 32.43%
Trewartha 13 35.14%
Neither 12 32.43%
Voters: 37. You may not vote on this poll

Old 08-19-2012, 06:36 PM
Location: PA
21,894 posts, read 14,779,780 times
Reputation: 9820


I've poured over the Trewartha classification system that seems to be the preference of some of the posters on here, more so the European and Oceania posters, and it's oddly more broad and simplistic than Köppen-Geiger. I think both has their good and bad points, I haven't been on here long enough to call myself a knowledgeable person on either system. So, as the climate classification novice that I am, educate me on why you prefer one system over the other, and the criticism/shortcomings of the system you oppose I prefer Köppen because that seems to be the system with the most easily accessible information on it and looks to be the more modern one. Trewartha, on the other hand, his map is confined to 2 scanned textbook pages (not the graphic that Köppen has) and almost all Wikipedia articles on climate reference the Köppen system. So, I prefer Köppen based on availability

Also, is there a detailed website that can fully explain to me how Trewartha classified each place in the world? I can only seem to find the map (that seems to have been scanned out of an old textbook) for his system. Not looking for a battle per se, but some education for us weather/climate novices (I've spent considerable time on here, but I know most of you are more knowledgeable than me in meteorology and climatology)

Last edited by theunbrainwashed; 08-19-2012 at 06:56 PM..
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Old 08-19-2012, 07:09 PM
Status: "waiting for spring" (set 18 days ago)
Location: Western Massachusetts
38,570 posts, read 25,104,756 times
Reputation: 12306
Those of us who object to both should post their climate classification
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Old 08-19-2012, 07:32 PM
Location: Wellington and North of South
4,464 posts, read 4,362,650 times
Reputation: 2017
My (probably unpopular) take on it: I have no interest in these schemes. For a given locality or region, I'm only interested in its specific climatology as it stands, and in what phenomena (the whole range from small-scale random fluctuations through meso-scale to global scale) can affect it on various timescales. If I'm considering a holiday in place X (or moving there to live), I'm not interested in its near-relatives elsewhere.
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Old 08-19-2012, 09:27 PM
Location: Vancouver, BC
7,170 posts, read 6,841,626 times
Reputation: 2769
I think I prefer Trewartha over existing systems as it seems more accurate in the temperate latitudes. However, that is not to say that Trewartha is the ultimate in climate classification systems.. I think that there could be a better one out there that I either don't know about or it hasn't been developed yet. I think both Koeppen and Trewartha both have their shortcomings with Trewartha coming out on top for the reason indicated above.
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Old 08-19-2012, 10:36 PM
Location: SW London
6,027 posts, read 3,097,702 times
Reputation: 1580
Trewartha has additional letters for the warmest and coolest month, so it's better for Oceanic climates than Koppen is.

For example; London and Sydney are both Cfb under Koppen, but under Trewartha, London is DObk and Sydney is CFbl.

From wiki:
'An option exists to include information on both the warmest and coldest months for every climate by adding a third and fourth letter, respectively. The letters used conform to the following scale:
i — severely hot: Mean monthly temperature 35 °C (95 °F) or higher
h — very hot: 28 to 34.9 °C (82 to 95 °F)
a — hot: 23 to 27.9 °C (73 to 82 °F)
b — warm: 18 to 22.9 °C (64 to 73 °F)
l — mild: 10 to 17.9 °C (50 to 64 °F)
k — cool: 0.1 to 9.9 °C (32 to 50 °F)
o — cold: -9.9 to 0 °C (14 to 32 °F)
c — very cold: -24.9 to -10 °C (-13 to 14 °F)
d — severely cold: -39.9 to -25 °C (-40 to -13 °F)
e — excessively cold: −40 °C (−40 °F) or below.'
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Old 08-20-2012, 12:07 AM
Location: Ann Arbor, MI
1,709 posts, read 1,975,986 times
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Overall, Koeppen with the 0C threshold for temperate-subtropical. I think some of the cooler Csb climates should be in the oceanic category and that the cool desert climates (BWn in Trewartha) should be classified, but other than that, I prefer Koeppen.

Originally Posted by B87 View Post
Trewartha has additional letters for the warmest and coolest month, so it's better for Oceanic climates than Koppen is.

For example; London and Sydney are both Cfb under Koppen, but under Trewartha, London is DObk and Sydney is CFbl.
Ah, it would be interesting to see a map using this. My thoughts on Trewartha being too broad were because of the maps, but this is good. I still prefer Koeppen because of the maps, but a detailed Trewartha map would probably be more accurate.
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Old 08-20-2012, 06:33 AM
Location: Laurentia
5,443 posts, read 4,271,398 times
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Koeppen-Geiger for me, with the -3C line between the Cxx and Dxx climate groups.

I also agree with RWood in that I'm more interested in the actual climate and history of a given place than which box it fits in.
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Old 08-20-2012, 06:36 AM
Location: Buxton, England
7,032 posts, read 5,837,675 times
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Trewartha, because it makes sense in the ways others have described. and for mid-lat climates. However, it still doesn't compete with my own definition which places subtropical climates with winters at least 8°C and summers at least 24°C for example.
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Old 08-20-2012, 08:42 AM
504 posts, read 569,830 times
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I prefer Koppen, with 0C for temperate-subtropical (personally I'd have it higher than that)

I prefer Cfb to Do and I don't like Trewartha's precipitation limit for Cs climates.

For Australia, I prefer the Australian classifications (like how the cooler subtropical climates are thought of as being temperate) and perhaps there are other countries with their own modified system that works better for them too, but I'm voting for Koppen out of the two.

On the topic of other classification systems, I have an Australian atlas that doesn't have a subtropical zone. It has a "warm humid" zone instead. I think for Southern Hemisphere places (since they are quite mild-to-warm-to-reasonably hot for all of the year), it's a good description instead of using the term subtropical.
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Old 08-20-2012, 08:47 AM
Location: London, UK
2,671 posts, read 2,879,153 times
Reputation: 1536
Koppen with the 0°C threshold.

If I were to modify it slightly, I would use 5C as a threshold, suppress the B category and instead use "x" as the precipitation letter for dry climates, e.g. Las Vegas would be Cxa, etc. (Two letters could be used, one for steppe climates, another for deserts, etc.)
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