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Thread: The Köppen–Geiger climate classification made simpler (I hope so)

  1. #11
      Pixie is offline
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    Hmm, this complicates things a little bit. But at the same time, it helps. It helps because now we can get a workflow that will yield more accurate climate maps and it complicates because that workflow will be a little more messy now.

    I tried to build a humidity map based on this info and on the scheme I mentioned earlier. It doesn't fit with climate predictions made like I suggested in the other thread in some places - namely, areas classified as savanna/monsoonal close to the tropics now seem Arid (desert?) all throughout the year and steppes at higher latitudes now have a properly Humid season, making them maritime/mediterranean.

    Azelor, you have definitely raised a point that can't be overlooked. I will need to review my stuff Thanks for that (or not! no, seriously, thanks for that)

  2. #12
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    You also need to be cautious with the numbers. For example, Jaipur is classified a steppe but receive a little more than R. Inside one climate one can see huge differences. Lisbon (Csb) is a Mediterranean climate but R=4 it's pretty wet. While Los Angeles (Csa) is barely above 1. It's not always clear because categories includes a broad range of possibilities.

    I like these formulas because they take into account that precipitation have a different impact depending when it fall.
    Logically, if precipitation evaporate at a slower rate in winter, the water (or snow) will stay longer in the environment and thus will have a bigger impact on nature. In theory.

    Two cities receive the same amount of precipitation for the year. City A is summer dry and City B is winter dry. Over the course of the year, which of the two cities will be the driest?




    areas classified as savanna/monsoonal close to the tropics now seem Arid (desert?) all throughout the year and steppes at higher latitudes now have a properly Humid season, making them maritime/mediterranean.
    plausible, but having a wet season does not always make the steppes a maritime/mediterranean climate. Only if they are not too far from the water.

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    Quote Originally Posted by Azelor View Post
    I like these formulas because they take into account that precipitation have a different impact depending when it fall.
    Logically, if precipitation evaporate at a slower rate in winter, the water (or snow) will stay longer in the environment and thus will have a bigger impact on nature. In theory.
    Yeah, that's the basic reasoning I think. That's what made me review the whole process - I am now going combo by combo, it becomes a huge table.
    5 january temperature levels x 6 january rain levels x 5 july temperatures x 6 july rain levels.... 900 entries.
    The original idea is to simplify climate prediction, 900 entries isn't simplifying. Still a work in progress...

    Quote Originally Posted by Azelor View Post
    Two cities receive the same amount of precipitation for the year. City A is summer dry and City B is winter dry. Over the course of the year, which of the two cities will be the driest?
    Did I say I am a science teacher? This is easy, when most of the rain falls in winter, moisture is available for longer. Thus, the location with rain in the summer is the driest.
    However... plants metabolism is very dependent on sunlight, so the location with rain in summer may have more vegetation cover as both factors for plant growth coincide, and a dry hot summer requires plants adapted to drought, which normally means smaller leaves and slower growth rate.

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    Quote Originally Posted by Pixie View Post
    Yeah, that's the basic reasoning I think. That's what made me review the whole process - I am now going combo by combo, it becomes a huge table.
    5 january temperature levels x 6 january rain levels x 5 july temperatures x 6 july rain levels.... 900 entries.
    The original idea is to simplify climate prediction, 900 entries isn't simplifying. Still a work in progress...


    Did I say I am a science teacher? This is easy, when most of the rain falls in winter, moisture is available for longer. Thus, the location with rain in the summer is the driest.
    However... plants metabolism is very dependent on sunlight, so the location with rain in summer may have more vegetation cover as both factors for plant growth coincide, and a dry hot summer requires plants adapted to drought, which normally means smaller leaves and slower growth rate.
    I think we need to make things complicated in order to understand the simples rules that makes the system. With some advanced statistics, we might be able to find interesting informations. I would like to see the file when it's done if possible.

    I got 10 temperature levels, what are your temperature levels?

    For reference, here's some numbers on climate aridity for different cities: I realize that a yearly classification for the wetness level can't include more than 3 categories because the variations are too great.

    Af:
    Paramaribo: 3,2
    Biak: 4,1
    Bluefield (Nic) 6,5
    Manaus: 3,5
    Davao: 2,6

    Am:
    Miami: 1,9
    Chittagong: 3,5
    Abidjan: 2,2
    Conakry: 4,7
    Douala: 4,4

    Aw:
    Caracas:1,3
    Mumbai:2,9
    Kaohsiung: 2,4
    Bangkok : 1,7
    Brasilia: 2,1
    Merida : 1,1
    La Havana : 1,4
    Bamako 1,2

    Bwh:
    Nouakchott: 0,15
    Port Sudan : 0,1
    Cairo: 0.04
    Djibouti: 0,2

    Bwk
    Ashgabat: 0,4
    Turpan: 0,03
    Lima: 0,0025 (Bwn)

    Bsh
    Jaipur: 1.06
    Gaborone: 0,6
    Mogadiscio: 0,5
    Niamey: 0,6
    Monterey: 0,8

    Bsk
    Bloemfontein: 0,6
    Granada 0,8
    Valencia: 0,9
    Tehran: 0,7

    Csa:
    Rome: 2
    Los Angeles: 1,2
    Perth: 2,2
    Beirut: 1,3
    Seville: 1,4

    Csb:
    Porto:4
    San Francisco: 2,1
    Cape town: 1,6

    Cfa:
    Durban: 1,5
    Tokyo: 3,2
    Sao Paolo 3
    Buenos Aires: 2,4
    Milan 2,4
    New Orleans: 2,9

    Cwa:
    Guadalajara: 1,4
    Lusaka: 1,3

  5. #15
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    Table isn't finished, but here's what I mean:
    The Köppen–Geiger climate classification made simpler (I hope so)-key_jan_veryhot.pdfThe Köppen–Geiger climate classification made simpler (I hope so)-key_jan_hot.pdf

    Table is being made in an excel file and the result exported to pdf like you see here. Starting point should be january temperature, then using magic wand on intercept, user would shorten selection with january rain, then july temperature, then july rain... (and, to cover the whole map, repeat that 900 times!)

    Any ideas are very welcome at this point.

    Also, as you can see, there are lots of combos which I have doubts about or which, even if I apparently don't have doubts I am plainly wrong about.
    If you have time, please give it a look - so far I only have these.

  6. #16
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    I'm really sorry, nobody noticed but I messed up my numbers pretty badly.


    In post 10: Minimal precipitation requirement
    The letters s and w represent the dry season, but I wrote that it was the wet season. So, winter dry always require more precipitations.

    (f) R=2 x T + 14 if rainfall is evenly distributed throughout the year
    (s) R=2 x T if rainfall occurs mainly in the cold season
    (w) R=2 x T + 28 if rainfall occurs mainly in the hot season.
    (T= mean annual temperature)


    Rain requirement to determine if a climate is dry according to temperature (mm)

    Severely hot: 35 °C or more
    (Minimal rainfall for 35°C, if the temperature is higher than that, more rain is required)
    Forever humid: R=840
    Summer dry: R= 700
    Winter dry: R= 980

    Very hot: 28 to 35 °C
    Forever humid: 700 to 840
    Summer dry: 560 to 700
    Winter dry: 840 to 980

    Hot: 22 to 28 °C
    Forever humid: 580 to 700
    Summer dry: 440 to 560
    Winter dry: 720 to 840

    Warm: 18 to 22 °C
    Forever humid: 500 to 580
    Summer dry: 360 to 440
    Winter dry: 640 to 720

    Mild: 10 to 18 °C
    Forever humid: 340 to 500
    Summer dry: 200 to 360
    Winter dry: 480 to 640

    Cool: 0 to 10 °C
    Forever humid: 140 to 340
    Summer dry: 0 to 200
    Winter dry: 280 to 480

    Cold: −10 to 0 °C
    Forever humid: 0 to 140
    Summer dry: 0
    Winter dry: 80 to 280

    Very cold: −25 to −10 °C
    Forever humid: 0
    Summer dry: 0
    Winter dry: 0 to 80

    Severely cold: −38 to −25 °C
    Forever humid: 0
    Summer dry: 0
    Winter dry: 0

    Deadly cold: −38 °C or below
    Forever humid: 0
    Summer dry: 0
    Winter dry: 0

  7. #17
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    But I also have some good news!
    If you look at the bottom of the previous post, you will notice that the coldest climates doesn't require rain at all. I have some doubts but that is was the formula says.

    climates that are classified humid but requires no precipitation

    No precipitation in winter: Dsb, Dsc, Dsd, Dfb, Dfc, Dfd,
    (apparently Dwd is still too hot in winter so he still need some precipitation, but it should be close to 0)

    ET: some area could be fine without any precipitations since summer temperatures are close to 0.

    EF: It's considered a desert but since it does not need precipitation at all, it could be considered humid as well. Humid desert !



    January

    cold
    rain: any
    humid

    July:

    mild
    rain: ...

    I'm trying to classify the Dsb climate using your classification but I'm not sure how to.

    • Precipitations: moderate
    o Summers = wet
    o Winters= dry
    • Average monthly temperature between -25 °C and 28 °C
    o Summer: mild to hot
    o Winter: very cold to cold

    the problem I'm having is that I know how much precipitation are required yearly but not for the specific seasons.
    I think I might have an idea, but it could make the numbers above useless.
    Last edited by Azelor; 07-30-2014 at 12:34 PM.

  8. #18
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    Quote Originally Posted by Azelor View Post
    I'm trying to classify the Dsb climate using your classification but I'm not sure how to.

    • Precipitations: moderate
    o Summers = wet
    o Winters= dry
    • Average monthly temperature between -25 °C and 28 °C
    o Summer: mild to hot
    o Winter: very cold to cold
    You're doing it again... Dsb means "dry summer"
    I would make it warm summer with arid or semi-arid conditions (low/dry rain patterns) and very cold winter with humid conditions (any kind of rain pattern except "dry" gives humid conditions in a very cold season)
    A mild summer would make it Dsc... A hot summer would make it Dsa... this is the sort of reasoning I am making in building the table.

  9. #19
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    I know. I chose this one as a test subject and realized I made a mistake. Another thing is that climates ending with b can't have hot summer. It's either mild or warm. Only the D's were wrong.
    I'm going to check the rest to make sure I don't have other mistakes.


    Finding the aridity of each area is complicated. Your trying to use a yearly formula to see if a climate is dry in one season in particular? I am correct?
    I don't know if it make sense to do that. We don't have the annual temperature or the annual precipitations. We just know that the driest month is < 1/3 of the wettest winter month. less than 30 or 40 depending if it's C or D.

    I have another idea. It will make it easier to decide if one climate is winter/summer dry or forever wet.

    first we need to set these assumptions:
    It’s in the northern hemisphere: july is in summer and january is in winter
    January is always the coldest month
    July is always the hottest month
    January is the driest month of the year (w=winter dry)
    July is always the driest month of the year (s=summer dry)

    Now, to determine the rainfall level, we use the Holdridge life zones.

    Average monthly precipitation (mm)

    0-5
    5-10
    10-20
    20-40
    40-80
    80-160
    160-320
    320-640
    640-1280
    1280+ ?

    (need better wording)
    f: precipitation levels are either on the same category, 1 category down or up.
    w and s: they are separated by at least one category

    example: Pixiland receive 30mm of rain in January and 70mm in July. =f because they are just 1 category apart.
    Azelor Town receive 15mm in July but 75 mm in January. It's a dry summer, category 20-40 is separating each seasons.

    Both climate could be considered humid, maybe one is more humid than the other but that's not too important.
    That way, it's simpler than the : precipitation < 1/3 of the wettest winter month
    and the numbers are not very different.
    Last edited by Azelor; 07-30-2014 at 06:16 PM.

  10. #20
      Pixie is offline
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    I see what you mean, and that makes it very easy to decide between a s-climate, a w-climate or a f-climate. But, that's 10 levels of rain.

    Say.. we keep the 6 levels of temperature as the current system gave pretty matching results in my test with ascanius and add more levels of rain.
    Instead of the existing 7, we add two more levels (could we merge the 0-5 with the 5-10?). The current process gives 7 levels, but I ignore the 6th and 7th.
    This can be done adding two layers in the present composition of rain patterns and I think it can be done in a few different ways.
    This could work, but it now becomes a 6 x 6 x 9 x 9 set of combinations.... 2916 different combos. That's complex enough, but we're getting to the point where it is impractical.

    If I may say, Azelor, you are focused on getting accurate at a given point, knowing the exact conditions, whereas I am focused in getting an overall map of the land. What are we trying to reach here?
    Last edited by Pixie; 07-30-2014 at 07:05 PM.

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