Talk:Köppen climate classification

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Köppen climate classification is obsolete and inaccurate[edit]

It would be necessary a paragraph aboout how much useless and unscientific is such classification

eg: it's simply ridiculous that someone could be taken seriously when includes inner Pakistan and even parts of Afghanistan, Tajikistan and Ethiopia in "mediterranean climate" LOL — Preceding unsigned comment added by 78.12.217.244 (talk) 00:46, 21 September 2016 (UTC)



How can anyone could define mediterranean the climate of these cities? Is it a joke?

Tashkent, Uzbekistan (Csa) Dushanbe, Tajikistan (Csa)

Medford, Oregon, United States (Csa)

Sacramento, California, United States (Csa)

Seriously.... the first one have a continental steppic climate, hot and dry summers and extremely cold and dry winters

the other ones have something like oceanic and continental/mild climates.


Not even Los Angeles should be included into Mediterranean climate, it's weather is semi-arid. — Preceding unsigned comment added by 62.10.248.54 (talk) 18:02, 21 September 2016 (UTC)

@62.10.248.54: No matter what objective criteria you use to separate climate, you'll end up with classifications that defy how they're commonly perceived. If you're upset about the Mediterranean climate classification, check out the Trewartha classification system. However, even that one has its flaws: it set out to reduce the area with a Mediterranean climate along the US West coast, but in the process, it nearly eliminated it altogether in California. It also expanded the 'oceanic' zone so much - in an attempt to classify the Pacific Northwest (west of the Cascades) in that zone - that it ended up with the strange result of including parts of Kansas as 'oceanic'.
I'd challenge you to create an climate system with objective boundaries that make everyone happy. Unfortunately, I don't think it's possible. Redtitan (talk) 03:18, 26 September 2016 (UTC)


objective criteria? it's not a matter of objectivity or subjectivity. Koppen classification is obsolete and extremely lacking. The modern climate classifications don't reduce the climate to 2 only parameters like Koppen's one does. The climate is not only the results of the average temperatures and precipitations. — Preceding unsigned comment added by 78.12.218.25 (talk) 13:38, 5 February 2017 (UTC)

Medford. Oregon and Sacramento, California are undeniably Csa. They both have winter rainy seasons and summer dry seasons. Medford is not coastal, and it is at a low altitude, and it is at roughly the same latitude as Detroit, which has a similarly-warm summer. (Detroit is definitely not Mediterranean).

Is the Koeppen classification obsolete? The connection between climate zones and agricultural potential is obvious enough. People in Philadelphia, San Antonio, and Tampa are likely to see their local climates more similar to those of Boston (Dfa), Laredo (BSh), and Miami (Am), respectively. than to the climates of the other three cities within the Cfa classification. Koeppen drew his lines where he did due to ecological realities, and not human perceptions of comfort.

The only way in which the Koeppen classification becomes elite is if some 'new' climate emerges -- perhaps a climate of extreme heat that makes plant growth unlikely irrespective of rainfall. Projections of the future of the Earth suggest that as the sun expands, parts of the Earth (most closely to the equator) will be too hot for warm-blooded animals and perhaps photosynthesis by large vascular plants. Pbrower2a (talk) 07:02, 8 December 2018 (UTC)

This classification is a huge joke, most of Spain is classificated as BSk what is a big mistake when it should be Csa in most of the cases. BSk is only found in Almería, Murcia, Alicante and Ebro valley.

The central Asian locations of Tashkent and Dushanbe have temperatures within the Csa classifications as both have winters at over 0 and plentiful rain along with the hot dry summers. Like it or not, if a winter has a coldest month between 0-18, even if it is much closer to the lower, it is still classed as "mild." — Preceding unsigned comment added by Galen1982 (talkcontribs) 03:43, 1 March 2019 (UTC)

Calculation of Köppen types - is it original research or a routine calculation?[edit]

Hello all,

I'd like to start a discussion about Köppen types and proper citation/sourcing. User Subtropical-man (talk / en-2) has called for a discussion and says that giving a location a certain Köppen climate classification type (such as by applying the rules for the Köppen climate classification system to climate data within an article, such as sourced data in a weatherbox) constitutes original research (for reference: Deep web:No_original_research). I welcome the chance to discuss this and come to a proper conclusion on how to move forward in line with Deep web policies.

According to what Subtropical-man (talk / en-2) is saying, any claim that a particular location has a certain Köppen type should be backed up with a citation to an academic source, otherwise it constitutes original research and should be removed. If I interpret that correctly, that change would mean some fairly radical changes to this article and to Köppen climate classifications for towns and cities across Deep web:

For instance:

-All non-sourced Köppen types would need to be removed from this page and the respective pages of towns and cities, as they’d violate a core Deep web policy, unless a cited source could be found directly referencing that location having a certain Köppen type. That’d require edits on thousands of different pages.
-Giving a town a Köppen climate designation would require sourcing, rather than applying the rules of the Köppen system to climate data, in order for a certain place to be given a particular Köppen climate designation.

Please feel free to weigh in below.


I’d now like to add my own personal thoughts. I would respectfully dispute Subtropical-man (talk / en-2) ’s point on two levels:

1) First, Deep web’s policy on when to cite states that citation depends on its likelihood to be challenged (Deep web:When_to_cite:
• If, based on your experience, a given statement has a greater than 50% chance of being challenged in good faith, either by removal, in a discussion on the talk page, or by the addition of a [citation ::needed] or similar tag, then you should supply an inline citation for that material.
• If, based on your experience, a given statement has a less than 50% chance of being challenged, then inline citations are not required for that material.
• If you are adding a controversial fact, it is best to always cite your source (see Deep web:Neutral point of view).
For pages where there’s continual controversy over a city’s climate type – say Madrid or Barcelona – having a citation makes sense. The climate types for those places are constantly being challenged. However, the climate type for a smaller town such as Wick, Scotland isn’t likely to draw much controversy (it’s quite firmly in the oceanic climate type).

In such cases, a citation would not need to be used. It still needs to be verifiable of course, as Verifiability is a core Deep web policy (see my next point).


2) Secondly, about the charge of “Original Research”, I believe applying Köppen type boundaries to climate table data would fall under the “Routine calcuations” exemption (for reference: Deep web:No_original_research#Routine_calculations.

That policy states that, “Routine calculations do not count as original research, provided there is consensus among editors that the result of the calculation is obvious, correct, and a meaningful reflection of the sources.”

The Köppen climate type guidelines are spelled out on the article, with a source attached. I think it’s fairly routine to look at the following climate table for Apia, Samoa and say it meets the standard of being ‘Af’ (Rainforest):

A: Minimum mean monthly temperature ≥18°C
f: All months ≥60 mm mean monthly precipitation


Climate data for Apia (Elevation: 2 m or 6.6 ft)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 32
(90)
33
(91)
32
(90)
32
(90)
32
(90)
32
(90)
32
(90)
32
(90)
32
(90)
33
(91)
33
(91)
32
(90)
33
(91)
Average high °C (°F) 30
(86)
29
(84)
30
(86)
30
(86)
29
(84)
29
(84)
29
(84)
28
(82)
28
(82)
29
(84)
30
(86)
29
(84)
29
(84)
Daily mean °C (°F) 26
(79)
26
(79)
26
(79)
26
(79)
26
(79)
26
(79)
26
(79)
25
(77)
25
(77)
26
(79)
26
(79)
26
(79)
26
(79)
Average low °C (°F) 23
(73)
24
(75)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
Record low °C (°F) 20
(68)
21
(70)
21
(70)
20
(68)
19
(66)
19
(66)
17
(63)
18
(64)
18
(64)
18
(64)
20
(68)
21
(70)
17
(63)
Average rainfall mm (inches) 450
(17.7)
380
(15.0)
350
(13.8)
250
(9.8)
160
(6.3)
120
(4.7)
80
(3.1)
80
(3.1)
130
(5.1)
170
(6.7)
260
(10.2)
370
(14.6)
2,850
(112.2)
Average rainy days 19 18 17 15 13 11 8 9 12 14 16 17 173
Average relative humidity (%) 81 80 80 78 77 75 76 75 75 77 77 78 77
Source: Weatherbase[1]

I think it’s reasonable to expect that multiple editors could conclude that a Af classification for Apia, Samoa is obvious, correct, and properly reflects the sources provided. It’s a simple mathematical process. It’s not as simple as calculating someone’s age – which Deep web lists as an example of a routine calculation – but it involves comparing a few numbers.

The only possible complication is for where there exist multiple isotherms for separating climate types, all with academic backing. In situations, I’m in agreement with the current situation for the two isotherms used in separating C and D climates: If you’re using the 0 deg C isotherm or the -3 deg C isotherm, it should be stated in the text.

I welcome all your input and hope we can have a calm and civil discussion about this.

Subtropical-man, I hope I've properly and accurately represented your thoughts here. If not, I apologize and I'd ask if you could clarify them here. Thank you. Redtitan 20:56, 4 November 2016 (UTC)

I do not really see the need for sources for climate classifications of locations. I mean, the criteria are objective and there's no uncertainty about the classification as long as you know which formulas are being used (for instance, whether the winter isotherm between C and D is -3 or 0 C, or which month range is used for the summer–winter half-years), what dataset you're using them on, and whether you did the math right. The math could actually be done automatically by a module, if someone wanted to create that. Then the determination would be completely objective and not open to dispute. It would be kind of neat if {{weather box}} had a function to automatically determine the climate classification based on the data displayed in the table. Then we wouldn't have to do the math ourselves, but just put the data into the table and see the result.
Using a source would be confusing when the source is using a dataset from one station and time period, and the weather box in the article is displaying a dataset from another station or time period. Then the article text would have to state that the classification doesn't agree with the temperature and precipitation variables that are actually displayed.
I'm curious, what sources could we use for climate classifications of locations? Weatherbase.com gives climate classifications, but often they are just plain wrong if you actually look at the data for average temperature and precipitation and do the calculations using the formulas. (I don't remember any specific examples at the moment.) I've also noticed errors on other sites. So those are not good sources to use. I don't know why they are often wrong (if they are using the wrong formulas or something), but for whatever reason they are. — Eru·tuon 00:04, 5 November 2016 (UTC)
I really like the idea of a weatherbox that automaticaly calculates climate types. I have no experience in setting such a thing up, but I can look into it. It'd automate a lot of work and would automatically update with new climate data.
I'm envisioning a cell in the weatherbox table with a background color matching the Köppen climate types in the maps. The text in the cell could be the type, linking to that climate type's article, like this: Cfb - Oceanic
Heck, maybe we could even have a cell with the Trewartha type. Just thinking out loud there. I know how to do the Köppen type calculations in my GIS program (I've even done some work in Excel). Maybe there's overlap in that coding and what would need to be done in a Deep web template. Redtitan 00:30, 5 November 2016 (UTC)
I think that idea of integrating the climate classification into the table sounds like what I was envisioning too. I would try to integrate climate classification into Module:WeatherBox (the module behind {{weather box}}), but I don't understand how it works enough to be able to find the average temperature and precipitation values in the module. I think it might work by only creating one row at a time, though, which might make it complicated to take the values from the average highs and lows, or average temperature, and the average precipitation, and do something with them... I'm very new to module coding anyway.
It would be easier to try making a separate module (maybe titled Module:Climate) that you can plug the monthly average temperature and precipitation values (or high and low temperatures, from which average temperature can be somewhat inexactly calculated) and that will output a climate classification. There could be an array of climate codes, names, and color values for each climate, which the module could use in producing the output text. — Eru·tuon 01:03, 5 November 2016 (UTC)

But that location is so obvious in one category. Some cities are borderline due to being close to a dividing line between climate zones (New York City is a prime example because the 0°C January isotherm goes through the city). Thus Coney Island is Cfa and the Bronx is Dfa by that criterion. A city that has a wide variety of terrains, like San Diego (the coast is steppe, but high elevations are Mediterranean due to higher rainfall). Because of differences in topography manifesting themselves in climate I would not use Salt Lake City or Denver as examples of any climate. One can use New York City, San Diego, Los Angeles, Denver, or Salt Lake City as examples of places in which classification creates controversy.

Locations used as examples should be unambiguous. There is some controversy on whether the isotherm dividing C and D climates is rightly 0°C (which puts New York City on the borderline between the Cfa zone Dfa zone, Coney Island Cfa and the Bronx Dfa, and puts Boston clearly in the Dfa zone) or -3°C (which puts the whole of New York City within the Cfa zone and Boston on the borderline between Cfa and Dfa climates. The difference? Daily averages under -3°C make the melting of snow unlikely, which means that snows can accumulate, and under bright sunlight, snow will evaporate at a temperature of 0″C. Koeppen established this in his original classification. Thus Mecca is definitely BWh, Tokyo Cfa, San Francisco Csb, London Cfb, Chicago Dfa, Stockholm Dfb, and the Scott-Amundsen Station at the South Pole as EF.

One could use Koeppen classifications for reconstructions (giving some leeway for imprecision) for the prehistoric past or projections of climate change. Models of climate change would find expression as climate boundaries change. Would the eastern divide between steppe and humid continental climates move into Minnesota from North Dakota and South Dakota? Would desert climates appear in southeastern Spain where they do not exist yet? Would tropical climates appera in southern Louisiana? I am not saying that projections and reconstructions fit Deep web standards. Pbrower2a (talk) 07:38, 8 December 2018 (UTC)

First, if the climate data is sourced and Koppen’s climate parameters are sourced, then there is no original research if you merely apply the sourced Koppen’s parameters to the sourced climate data. It’s firmly based on sourced material. Secondly, some seem to be in an uproar that NYC is humid subtropical. This seemingly bizarre classification for NYC is almost certainly symptomatic of climate change. NYC has almost always used Central Park as the official weather station. Most of the city is within the category. If we started to get specific about climate types based on specific locations we can overload on details. San Francisco and San Jose has a number of microclimates. Los Angeles’ climate can go from mild-summer Mediterranean to hot-summer Mediterranean to semi-arid. Miami can go from tropical monsoon climate, to tropical savanna climate to tropical rainforest climate depending on the station used. Sections of the Tampa Bay area are apparently tropical depending on location. The best guideine is whether most of a specified area falls within an area, particularly its main weather station. G. Capo (talk) 21:24, 13 December 2018 (UTC)

References

  1. ^ "Apia Climate Info". Weatherbase. Retrieved 4 November 2012.

Azores is not a country[edit]

I see that for the subtropical humid (Cfa) climate, (Horta) Azores appears as a country. But Azores is in Portugal. There´s no country with the name of Azores. So I removed Azores and placed Horta, Portugal there. Also there are some cities on the Cfa list, that have dry months in the summer... Those exact locations, therefore cannot have a Cfa climate. Be careful with that and confirm with their respective climatograms. And I´m not even sure that Horta is Cfa. Corvo or Flores island (both also in the Azores islands), one of those surely is, because I do remember to have discussed that in the past and saw some climatograms that confirmed it. It´s possible that other Azores islands have it, but I´m sure that one of those 2 (Flores and Corvo) had it. — Preceding unsigned comment added by 188.37.171.168 (talk) 03:29, 22 February 2017 (UTC)

There are two criteria for determining a dry summer. One is that the place must have a dry summer month under 30 mm. Secondly the wettest winter month must have over 3 times that of the driest summer month. So a place could have a driest summer month of 29, a wettest winter month of 85 and therefore it would not be considered "dry summer." Such a place might still have enough rain to avoid an overall dry classification, particularly if there were also very wet summer months. I will give a fictional data set, don't have time to look for a real example. The location has a mean temperature of 17°C and is in the Northern Hemisphere. The rainfall figures are 81, 62, 73, 44, 28, 60, 53, 105, 89, 72, 64, 69. This equals 800 mm. The summer/winter distribution is even. Therefore it needs under 480 to be B (assuming I don't have to explain that math). So it is clearly not a dry climate. The summer month of May has 28 mm, but the wettest winter month (January) has 81, therefore it falls under the necessary 3 ratio for a dry winter (2.9). So it is not dry summer. The ratio of the wettest summer month to the driest winter month is 1.7, under the 10 necessary for a dry winter. So overall it does not have a dry summer or winter and is therefore Cfa. — Preceding unsigned comment added by Galen1982 (talkcontribs) 03:18, 1 March 2019 (UTC)

-3 instead of 0[edit]

Using 0 as the border between temperate and continental is apparently only an American thing, so I think we should use the -3 system instead, as that is apparently the normal in other parts of the world, and the vast majority of people are not American. Socialistboyy (talk) 23:03, 7 April 2017 (UTC)

What is the reason for the different isotherms? I’ve been searching all over the place and usually the article reference the works written by Russell (Dry climates of the United States. I. Climatic map - Russell - 1931), Wilcox (or sometimes Wilcock -- Köppen after Fifty Years - Wilcock - 1968), Essenwanger (Classification of Climates - Essenwanger - 2001). I can’t find any of these online and nobody who references them bothers to explain their reasoning for the -3 --> 0 change.

Some bits I found:

The delimitation of California's areas of microthermal climate (Ds) is based on the January isotherm of -30 C. in Figure 3 and on the January isotherm of o? C. in Figure 4. The latter delimitation yields a better correlation of the regions of D climates with the areas of heavy snowfall where snow commonly remains on the ground for more than a month. The use of the o? C. isotherm for the delimitation of D climates in California is thus preferable, as was shown by Russell fifteen years ago.
and
He discusses at length the most suitable criteria for separation of cold (microthermal) and warm (mesothermal) climates, and claims that for North America as a whole the line of the 32° F. January isotherm is superior to the 50° F. isotherm proposed by van Royden (Monthly Weather Review, 1927) or the more elaborate basis in Koppen' s later classification (mesothermal = mean temperature of one month under 18° C. [c. 64° F.] and at least 8 months above Io C. [c. 34° F.]). He has already shown the value of the 32° F. line in California in an earlier field study (The Climates of California, this series, Vol. 2, No. 4) and now points out its close correspondence with important vegetational boundaries in the arid areas (especially between the creosote scrub to the south and sage brush to the north). Further east it corresponds remarkably closely with the northern boundary of the Corn
How is this US-centric system gaining traction?
Does anyone have any of the 3 articles I mentioned?
Where can I read more about the change of the average temperature of the coldest month classification change? (btw, sorry if this isn’t formatted properly. I don’t normally edit wiki talk pages and I don’t have an account. This was added on 29th May 2018. — Preceding unsigned comment added by 31.15.137.53 (talk) 16:21, 29 May 2018 (UTC)

BWn[edit]

What's the definition of the mild desert climate (BWn) climate? Both this page and mild desert climate just give general adjectives to describe it, no definition in terms of average monthly temperatures. — Eru·tuon 07:46, 11 May 2017 (UTC)

...also applicable to BSn as in coastal San Diego, California) and some humid climates (San Francisco, California, has a Csbn climate)...

The small n (N for German Nebel, or fog) refers to the commonness of fog in places in which cold currents frequently preclude hot weather at a coastline in tropical, subtropical, and temperate locations. It applies to places that are too cool in the summer to be truly hot but too warm in the winter to qualify as having cold winters. Most deserts and steppes have hot summers and cold winters for the latitude. Along western coastlines of the continents, the offshore cold current may prevent rainstorms that would otherwise create humid conditions. (In zones of Mediterranean climate, like the central coast of California, the cold current moves poleward in the summer and establishes a zone of extreme seasonal drought. But the air may be saturated in moisture! Pbrower2a (talk) 03:54, 7 December 2018 (UTC)

The BWn/BSn is used as a modification for classifying the climate of Chile to describe the desert climate founded in the coastal areas in Chile, which is described already above by Pbrower2a as being a unique case. I thinking the n is more of description than rather than being used for classifying the climate as the Peel et al (2007) nor the Beck et al. (2018) uses it. For example, one of the sources describes Central Chile's climate as Csbn with frequent fog in the winter, indicating that n is just used for descriptive purposes and not really based on some temperature or precipitation thresholds that the other letters would use. It is a misnomer to call it mild desert climate as originally, the BWn is technically described as a desert climate with frequent fog without regards to temperature and would be original research and unsourced. My biggest concern is what is the criteria used to define a location as having a "mild desert climate"? In fact, the section on mild desert climates, since it was first added in November 2009 (based on the desert climate editing history) has been unsourced for 9 years. I have removed the BWn, BSn categories in the Köppen climate classification with this edit but kept the definition of using the n (it is not a third letter). Ssbbplayer (talk) 00:16, 11 December 2018 (UTC)

Reference problem and those pretty flag bits[edit]

The lists in the article are unsourced (only one location has a ref). I've also again removed the redundant links including the "colorful" but meaningless (in this article) flag icons. Please address the reference problem and explain the need for the flags (other than making the article "more attractive". Vsmith (talk) 01:23, 9 March 2018 (UTC)

I’ve again included the flags. There isn't a problem here. If you go to each city’s climate section, you should find the climate chart for that city, which is typically sourced. Utilizing Koppen’s parameters (or calculations in some instances) you’ll find that the climate classifications for the cities are generally accurate. As for those “pretty flag bits”, since you’re the only one who has raised objections about it (and the only one who seems hell-bent on removing them), is there any reason why you feel it is of utmost importance to take the flags down? Other editors have thanked me for including them in the article. G. Capo (talk) 22:08, 9 March 2018 (UTC)
And you have re-added a bunch of redundant links:
In this single line you have two links to Colombia and that is redundant. Beyond that in your revert you re-added that link to Colombia even though Colombia is linked in the line just four lines above:
  • Colombia Medellín, Colombia (Af) - the result is four links to Colombia in close proximity - and that is rather in violation of MOS:OLINK and that problem is abundant in the article. And just below are 4 links to Brazil. As for the United States in the article - how many links are there? Each line of a US city has two links to the United States. I do see you were a bit inconsistent on that in your last edits.
I consider the "colorful" flag icons to be unhelpful verging on unneeded jingoism; they simply add nothing to the article and are a distraction in addition to violating overlinking policy.
As for the reference needed tags - Deep web articles essentially need to be independent and are not referenced by articles linked within. Examples: the Valdivia, Chile article which does say Oceanic climate, but with no source except for the climate table. But, if you look at the Collinsvale, Tasmania article - there is no climate data. So it seems the article does need references - as the linked articles don't always provide that support.
So, the problems are excessive link redundancy, lack of references in the article, and what I call colorful clutter which adds nothing to the article except redundancy and distractive jingoism. Please address each point in your response. Thank you. Vsmith (talk) 00:02, 10 March 2018 (UTC)

Too many "example" links[edit]

The article is cluttered with far too many links to cities or locations supposedly exhibiting the climate types, especially as the lists are not supported by references. I would suggest paring down those lists to just a few examples that can hopefully be backed with solid references. Vsmith (talk) 00:30, 15 March 2018 (UTC)

That is a really good idea. There are about 40 examples of BS climates, which is at least 30 too many. It would be best to pare these down to a half dozen or so well known places so the reader gets a better idea of what a climate is like. In fact I may be boldly start doing just that. Shock Brigade Harvester Boris (talk) 01:08, 15 March 2018 (UTC)
Apparently when we need to prune examples, we need to prune “third world” examples. Tropical Rainforest Climates are most commonly found in “third world” nations. They should be represented here. G. Capo (talk) 17:01, 23 April 2018 (UTC)
The problem is that a lot of these locations cites climatedata.org, which is unreliable because on their website, they explicitly stated how their data is modelled data and not observed data. Observed data is obviously more reliable than modelled data due to the inherent errors that modelled data has (e.g. not taking in account of local topography and microclimates). Any city that cites that source and included in here, should be removed from the list. Ssbbplayer (talk) 05:24, 22 September 2019 (UTC)

Recife, Brazil[edit]

Recife's climate is classified here as Dry-Summer Tropical Savanna (As), but according to the city's article page, it has a Tropical Monsoon (Am) climate. Which one is correct? Heavyarms2025 (talk) 02:21, 6 November 2018 (UTC)

The article. Recife receives nearly 2500 mm of precipitation and it has at least one dry season month. If you run the calculations based on the data, it isn’t a tropical savanna climate. I've changed this article to reflect that fact. G. Capo (talk) 16:47, 8 January 2019 (UTC)

Climate map of Europe[edit]

At the end, where we find the climate maps for continent, on the map of Europe is missing the climate type BSh, which is refered with color pink, and is located in the southeast Iberian Peninsula (near to Murcia). Thanks!--186.59.227.179 (talk) 19:15, 30 January 2019 (UTC)

Possible Double Ups and Other Issues[edit]

There are at least five situations which could be said to fit into two classifications. Two of these definitely exist (one which appears two have an obvious answer). The other three are probably theoretical only (one of which appears to have an obvious answer).

A) B or E?

As temperature drops, the threshold for "dry" also drops. E places usually have very low average annual temperatures and at certain levels the dry threshold becomes negative when one does the math. If a place is driest in the summer and has an average below 0°C, it is "moist" at any precipitation level, if the rain or snow is evenly distributed and it is below -7°C it is automatically moist and if the winter is the driest and the average is below -14 it is also automatically moist. However on Climate-data.org I have discovered some very high locations in Bolivia that average below 10°C in every month and are also dry. These places due to their tropical location have low ranges of monthly temperatures so lack the extremely cold months of most E climates, some of them average around 6-7°C but I will use the coldest location in Bolivia recorded on the site as an example. Rio Blanco has an elevation of 4810 m, an average temperature of 2.2 (5.8 in January and -3.0 in June) and just 51 mm of precipitation of which 100% occurs during the summer). We can use these figures to calculate a dry threshold of 324 mm and it only has less than 16% of this figure so it is well and truly desert if a climate can be "B" with all months averaging under 10°C. It seems that such places are typically classified as E regardless of their precipitation.

B) C and D climates with dry months in both summer and winter

When factoring dry seasons for C and D climates, a summer is considered dry if the driest summer month has less than 30 mm and the wettest winter month has at least 3 times the amount of the driest summer month. The winter is dry if the wettest summer month has 10 times that of the driest winter month, regardless of how much the latter month has. This creates the potential for at least one dry month in both summer and winter, which actually exists in some places in Central Asia. The climate data website tends to classify such climates as dry summer, even in the following extreme example. Dehradun is a city in Northern India that is classified on the website as Csa (subtropical dry summer). Here are its rainfall figures, temperatures are not needed for this exercise 63 42 56 16 45 149 545 567 276 96 17 24. The driest summer month is April (16) and the wettest winter month is October (96).So it is correct to say that there is one dry summer month. However the driest month of winter is November (17) and the wettest summer month is August a whopping 567. It is frankly ridiculous to say that overall this place has a dry summer. It is extremely wet from July to September (interestingly the average temperature peaks at May and June). Overall the summer percentage is nearly 84 (1588/1896). It seems to have been classified as Csa on a technicality, the decision to determine a dry summer before a dry winter. Not sure if this is a convention or just used by the website, the Deep web article doesn't give examples of this situation. I would think that the best decision here would be to classify the season that is driest overall as the dry season.

C) Af or B?

The theoretical minimum for an Af climate is surprisingly low at 720 mm (60 x 12). In contrast an Am climate has a 1000 mm limit. The example here is theoretical only as I doubt that there are any existing climates with barely 720 mm of rain in a year that are also Af, due to the fact that tropical climates, even without a marked dry season, have uneven seasonal distributions of rain. The Climate Data website gives some Af locations in Brazil with around 1200mm and I doubt any are drier. There is no theoretical maximum precipitation level for a dry climate given that it goes up as the temperature rises. To avoid fence sitting at 60 mm in any month, the fictional example here as 61 mm in every month or 732 mm overall. It has an annual average temperature of 30°C. The rainfall is obviously evenly seasonally distributed, meaning this place needs 740 mm to avoid being dry (30x20+140). I think it would definitely be classed as dry, given that A, C and D climates must be above the dry threshold.

D) Hottest month over 22°C but less than 4 months over 10°C

Again I doubt if this scenario exists. If it did, it would almost certainly contain months below 0°C (or -3°C depending on which one is used). So it would be a D rather than a C. Determining dry seasons isn't the issue here so for argument's sake I will say it has no dry season (Df). The question is, would it be a Dfa because it has a month over 22°C or Dfc due to having insufficient months over 10°C. From what I know of the Mongolian climate, this would appear to be a possible analysis for a given year with an abnormal summer heatwave but probably not a long-term average. Also due to the Mongolian low rainfall, the place would have to avoid being B first.

E) Coldest month under -38°C but 4 or more months over 10°C

The climate over much of Siberia is Dfd, the same as the regular subarctic (Dfc) except with even colder winters including at least one month under -38°C. So what would happen if a place had winters that cold but a slightly longer summer with 4 months over 10°C? Dfb or Dfd? (It is not worth bringing the possibility of a month over 22°C to the discussion here as it would clearly be impossible). This is again more likely to be the analysis for a given year rather than an average figure, in the event of an abnormally warm September. It seems likely that the reason the severe winter was set as low as -38°C was to avoid the possibility of this clash. I live in New Zealand and find anything below zero as severe but even most people living in the US would find a month that averaged -10°C (14°F) as severe.

Other Issues

Dry climates deserve more temperature information. At the moment, depending on what system you use, they are merely classed as hot or cold, depending on if you take an average of above 18°C or all months above 0°C as the cutoff. The latter is particularly problematic, making some "cold" climates having higher averages than some "hot" climates. Dry climates exist with all the temperature classifications of the A, C, D and E categories and this is relevant information that should be incorporated somehow. Pointing out the problem with treating a climate with all months below 0 as "hot" it is true that most such locations would have very hot summers but there are exceptions. According to Climate Data, Oruro in Bolivia (height 3719 m), averages 11.3°C in January, 2.4°C in June, average overall 8°C and 394 mm of rainfall, mostly in summer making it a semi-arid climate. The website uses the under 18 classification, making a BSk, but if you use the alternative definition, which Deep web states is currently most fashionable, it is a hot dry (BSh) climate because all months average above zero, when it is clearly not a hot place by any "normal" person's definition). There are also a few dry climates with moderate year round temperatures such as Northern Chile, the coast of Namibia and the high altitude Sana'a in Yemen.


It is theoretically possible to step across the equator from an As (tropical dry "summer") into a BSh climate because you would have a dry "winter" and increase the dry threshold. This points out the limitations of rigidly applying adding 280 for a dry winter, 140 for even distribution and 0 for a dry summer at places that have uniform temperatures. The situation appears unlikely. Savannah climates are rare in the immediate vicinity of the equator which is typically Am or Af, but Climate Data has some South American locations which are as such. They are much too wet to risk being BSh however. A location with an average temperature of 26°C and a dry "summer" needs under 520 mm. When you step across the equator into the dry "winter," this figure increase to 800 mm. The Savannah areas outside of the area very close to the equator seem to exclusively have winter as their dry season.

Finally a "precipitation-heat" index would be a more useful tool for casual data observers than total precipitation. This would be a ratio of total precipitation divided by the dry threshold, possibly multiplied by 100. Climates that were A,C or D would have indexes over 1 (or 100), BS climates would vary from 0.5 to 1 (or 50-100) and BW climates would be under 0.5 (or 50). E climates could have any index. There are points for very cold climates, depending on seasonal distribution, where doing the math would result in negative numbers, these would have to be indicated as index not applicable. The classification system is not imperial unit friendly (not an issue for me as I live in New Zealand). Using rounded figures, to determine dryness for imperial units multiply the annual average Fahrenheit temperature by 0.44 and subtract 14 if more than 70% of the precipitation is in the winter months. For an even distribution, subtract 8.5. For more than in the summer, subtract 3. This will give you the dryness threshold in inches.

Sources Climate-data.org Galen1982 (talk) 02:58, 1 March 2019 (UTC)

To my comment about potentially crossing the equator from a Bs climate into a semi arid climate I have found on the Climate Data website that this does actually happen in Somalia. This country has only a small portion south of the equator and in this area the wet season is the northern summer. I had only examined South American equatorial regions, not African, I'm pretty sure all of Indonesia is very wet. Anyway it appears that several southern Somalian stations in the Lower Juba state have mean temperatures of around 27°C and annual rainfall of about 550 mm. For a dry "summer" this only just crosses the dry threshold sufficiently to create a dry "summer" savannah (As) climate (540 mm). North of the equator when "winter" is the driest season, the threshold increases to 820, meaning the area is well and truly BKh. Again it reflects the limitations of adding a factor for dry "winter" or "summer" in an area where these terms are virtually meaningless. I suspect I will find a similar situation in some Kenyan stations, though further west in the African equatorial region places tend to be much wetter. The website has literally millions of stations and is clearly automated in terms of computing classifications. Longitude and latitude information are not given for each station so I can't tell straight away for an unfamiliar station in an Equatorial country which side of the equator it is on, but in these instances, having temperature so high and rainfall so low means that it can only avoid being a B climate by having a dry "summer" so it's then a case of looking at the data to determine the drier season. — Preceding unsigned comment added by Galen1982 (talkcontribs) 09:44, 1 March 2019 (UTC)

I think some of these issues are solved by having a fixed order in which a climate is assessed for the various categories. For a theoretical Af/BSh marginal climate, I think you'd first determine whether it was semi-arid and then if not proceed to determine whether if was Af. This avoids the problem of a climate being simultaneously Af and BSh. In practice I doubt there are any marginal climates of this type as climates this warm year round with barely 60 x 12 mm of rainfall tend to be highly seasonal in rainfall; Af climates with consistent monthly rainfall tend to be very wet, with a lot more than 720 mm of rain. One also runs into the problem that for a climate with 60 x 12 mm of rainfall to be BSh it would need to have an average temperature of more than 29C, which is getting towards the hotter limits of climates of this type. Booshank (talk) 19:16, 19 March 2019 (UTC)

Cwc & Dsd[edit]

Why are there no listed samples of climate type Cwc and Dsd? — Preceding unsigned comment added by 69.206.181.191 (talk) 01:02, 26 April 2019 (UTC)

Three country examples in each climate section.[edit]

I don't understand why G Capo says only three is enough for those cities. In some big countries with a predominant climate zone, it's fine to add more than three country examples. 2607:FEA8:A2A0:1880:5CAC:3B9D:6923:8D98 (talk) 21:11, 14 August 2019 (UTC)