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Thread: WIP (sort of tutorial to be) : Climates, applying Geoff's Cookbook at detail (some)

  1. #21
      Pixie is offline
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    Thanks for the interest Azelor, it's good to know more people are reading and it's not just a 4/5 men show

    Quote Originally Posted by Azelor View Post
    Yes but the latitudes are curved with the Hammer projection so you'd also need to curve your temperature zone (but the impact is minor if you only intend to make this continent)
    Indeed, I couldn't be bothered to curve my temperature zones since I was only using the center of the map. But, if I were to do it again, I would stick to equirectangular map
    or make a "flat" image with the temperature zones and then project it using g.projector. In fact, that's a path worth exploring one of these days for continents at higher latitudes - playing around with non-equatorial projections.

    Quote Originally Posted by Azelor View Post
    I would like to know if your using a particular climate classification for this? It would be good to know how hot is the ''Very Hot'' area.
    Coming up soon. I started using the table from Geoff's web page, but it left out a lot of areas after using my system for rain and temperature. I have a revised table that covers more variety and I will post it soon. It relates directly to Koppen classification, although it still merges a few zones (less than Geoff does). I'm working on the last-but-not-least bits of that.


    Quote Originally Posted by Azelor View Post
    As a side note, your continent is small to have any real continental influence unless I'm missing something. Maybe there is but it's very small as you said in point 4.
    The southern portion is pretty massive. It's being so close to the equator that distorts the perception of area - but it's more than twice as big as Australia and about 1000 km wider than North America (the southern portion that is).
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  2. #22
      Azelor is offline
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    Yea I'm reading it and also other threads but only answer from time to time.

    Quote Originally Posted by Pixie View Post
    The southern portion is pretty massive. It's being so close to the equator that distorts the perception of area - but it's more than twice as big as Australia and about 1000 km wider than North America (the southern portion that is).
    Funny, because Hammer is supposed to prevent area distortion. But not the shape. Well, then it make sense.

    As a side note, I'm working on something on the Koppen climate. I'm trying to make it ''easier'' to understand or so I hope to. Because frankly, climates are complicated and the english wikipedia page is a mess.
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  3. #23
      Pixie is offline
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    Well, Azelor, in that case, I am really really interested in reading what you have to say about my system (see the posts below). While the whole thing makes sense to me, I am not sure at all if I am missing important aspects or not.

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    Default Step 7, the climate zones (how to find them)

    Reaching the final stage of all this work.

    Now, we start to find out the actual climates. This is based on Koppen's classification, but somehwat limited, since we only have graphical information for the extremes. The result will always need some polishing and some reviewing, so you need to understand a little bit about climates. My advice is to follow the steps below and AFTERWARDS, compare your map with Koppen's Climate Classification, at Wikipedia, to see how it compares or with real life locations in similar geographical conditions.

    So, let's put our maps to use.
    All it's needed now is the four maps we produced in the previous stages:
    - January and July Rain Patterns
    - January and July Temperature

    You are going to use the magic wand a lot, sometimes in "addictive mode" (enlarging a current selection with the area under one color), sometimes in "subtractive mode" (excluding an area under a given color from the current selection) and sometimes in "intercept mode". Identifying every bit of a particular climate is a matter of fitting a number of conditions, so I'll slowly go step-by-step for the first one:

    1. HOT DESERT (BWh)
    - at least one of the seasons as Warm/Hot/Very Hot
    - no season as Cold/Very Cold
    - both seasons dry

    So I need to find the areas that "fit" all these three conditions:
    Looking at January Temperature map, I select all areas under dark red, red and orange (adding them).
    Then I switch to July Temperature and I exclude the areas in light blue or colder from this selection.
    Thirdly, using one rain pattern at a time, I intercepted the selection with the DRY areas.


    This sequence of pictures shows the selection area getting smaller (the region under diagonal stripes), step by step.
    WIP (sort of tutorial to be) : Climates, applying Geoff's Cookbook at detail (some)-instructions_for_selecting.gif

    The resulting area is painted in a solid color in a separate layer. Which I name after the climate - one climate per layer (easier to adjust later, if need be).
    But it wasn't all done yet for this climate. I checked January being the warmest and July could be mild, I need to repeat the process for the remaining combinations. After which I got this result:

    WIP (sort of tutorial to be) : Climates, applying Geoff's Cookbook at detail (some)-deserts_in_palamb.gif
    This is a very desertic land, I can see that now. It contains two huge deserts plus a few pockets and two small "coasts of death". But let's find out about the rest of the continent, there has to be some place where people can live and farm comfortably!

    My choice of colors comes from this map.
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  5. #25
      Pixie is offline
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    Default Step 7 (part two), temperature and rain conditions for every climate

    Word of warning: the following is a lengthy task. There are 4 variables (4 maps) and a lot of possible combinations. This will take time. The end result, however, is very rewarding, and I'll show you a neat map in the next post... for now, here's the list of climates possible and how to find them:

    (Some climate classifications have been merged)

    1. HOT DESERT (BWh)

    - at least one of the seasons as Warm/Hot/Very Hot
    - no season as Cold/Very Cold
    - both seasons dry

    2. COLD DESERT (BWk)
    - at least one of the seasons as Mild/Cold/Very Cold
    - not qualified as Hot Desert
    - both seasons dry

    3. TROPICAL MONSOON (Am)
    - no season is below Warm
    - one season Wet/Very wet and the other Low/Moderate

    4. TROPICAL RAINFOREST (Af)
    - no season is below Warm
    - rain Moderate or above in both seasons
    - not qualified as tropical monsoon

    5. SAVANNA (Aw)
    - no season is below Warm
    - one season Very Wet/Wet/Moderate and the other Dry
    (OR Moderate and then Low)

    6. HOT STEPPE (Bsh)
    - no season is below Mild
    - both seasons are Low or one is Low and the other is Dry

    7. COLD STEPPE (Bsk)
    - both seasons are Low or one is Low and the other is Dry
    - colder season is Cold
    OR
    - colder season is Very Cold and warmer season is Warm or above

    8. MEDITERRANEAN (Csa)
    - one season Hot/Warm and one Mild
    - warmer season is Dry/Low and colder season is Wet/Moderate

    9. COLD MEDITERRANEAN (Csb/Csc)
    - one season is Hot/Warm/Mild and one is Cold
    - warmer season is Dry/Low and colder season is Wet/Moderate

    10. TEMPERATE MONSOON (Cwa)
    - one season is Hot/Warm and one is Mild
    - warmer seaon is Very Wet/Wet/Moderate and colder is Dry/Low

    11. TEMPERATE HIGHLAND OR SUBTROPICAL (Cwb/Cwc)
    - one season is Hot/Warm/Mild and one is Cold
    - warmer season is Very Wet/Wet/Moderate and colder is Dry/Low

    12. HUMID SUBTROPICAL (Cfa)
    - one season is Hot/Warm and one is Mild
    - warmer season is Very Wet to Moderate and colder is Moderate/Wet

    13. MARITIME TEMPERATE (Cfb)
    - one season is Warm/Mild and one is Cold
    - both seasons are Moderate/Wet/Very Wet (or
    - not qualified as Humid Subtropical

    14. MARITIME SUBPOLAR (Cfc)
    - one season is Warm/Mild and one is Very Cold/Extremely cold
    - both seasons are Moderate or above

    14. MANCHURIAN (Dwa/Dwb)
    - warmer season is Hot/Warm and colder season is Very Cold
    - rain is Very Wet/Wet/Moderate in warm season and Dry in cold season

    15. LAURENTIAN (Dfa/Dfb)
    - warmer season is Hot/Warm and colder season is Very Cold
    - rain is Wet/Moderate in cold season and Moderate/Low in warmer season

    16. CONTINENTAL HIGHLAND (Dsa/Dsb)
    - warmer season is Hot/Warm and colder season is Very Cold
    - rain is Dry/Low in colder season and Moderate/Wet in warmer season

    17. TAIGA (Dfc/Dsc/Dwc)
    - warmer season is Warm/Mild and colder season is Very Cold/Extremely Cold
    - not qualified as Cold Steppe or any other D-type climate

    18. TUNDRA (ET)
    - one of the seasons is Cold and the other one is colder

    19. ICE CAP (EF)
    - temperature is always Very Cold or Extremely Cold

    EDIT 1: fixed/revised some "rules" for D climates.
    Last edited by Pixie; 07-17-2014 at 07:40 PM.

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    Default Step 8 (AND FINAL!), neating things up

    So, you went through all the climates and the map looks a mess (or not). Well, climates can be a mess, and the magic wand may not select some pixels, and you may have overlooked some combinations - the remaining is to be done by hand.

    And we can start by the following
    - there is probably an area very close to the equator that appears to be desert, between areas of savanna or monsoon... Well, it is savanna or monsoon! it's the rainy season in that region that doesn't match january or july (the ITCZ passes through in a different month, in its north-sound annual movement), so it slipped right under out radar.
    - in some parts, a transition climate may not be appearing (like tropical monsoon between rainforest and savanna, hot steppe between hot desert and mediterranean, cold steppe between cold desert and continental, etc), add a strip of such climate manually and delete what was there before.

    Then, you need to find out bits that aren't colored in any particular color and find the best fit manually (comparing with available information on Koppen classification, like I said before).

    Thirdly, time to merge it all together and make it final. But I recommend you duplicate all the layers and simply merge the copies, just to be safe. Once this is done, you can smooth boundaries between regions, make very small micro-climate regions disappear if they are cluttering the map too much, etc.

    After some work, including adding a key and a title (work-in-progress, still), this is my end result for the continent of Palamb:
    WIP (sort of tutorial to be) : Climates, applying Geoff's Cookbook at detail (some)-final-presentable-.jpg
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  7. #27
      Naima is offline
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    Can u type in also a real wprld sampleof ur climatic zones prototypes? For example cold desert is like Gobi or Atacama?

  8. #28
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    Quote Originally Posted by Naima View Post
    Can u type in also a real wprld sampleof ur climatic zones prototypes? For example cold desert is like Gobi or Atacama?
    I don't know. Honestly, I think it depends on the location and there was no way it could get that detailed. Read through the wikipedia page on Koppen's Climate Classification, it helps.

  9. #29
      Azelor is offline
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    I will comment from the beginning:

    I still have no clear idea of your temperature classification but I'm going to take a guess:
    extreme is below -38, very cold is below -10, cold is below 0, cool 0-10, mild 10-18, warm 18-22 ?, hot 22-32, very hot is over 32 degree Celsius


    BSh and BSk: small detail but it's S and not s, otherwise it mean summer dry
    these two climates can have a rainy season, some places could receive up to around 200mm of rain in a month because they are subject to the monsoon (mostly the hot one). Large parts of the steppes in Africa and Eastern Asia are affected. Examples include Niamey and Hohhot.

    BSk : is usually found at higher altitude than the hot desert

    Dont forget that : (I know it's pretty complicated!)

    B. Dry climate: Annual evaporation is greater than precipitation (also called potential evotraspiration). To determine whether a location has an arid climate, the precipitation threshold must first be determined. The threshold value (in millimetres) is determined as:
    • If less than 30% of annual precipitation occurs in the summer : Annual precipitation (mm) < 20 × average annual temperature (°C)
    • If more than 70 % of annual precipitation occurs in the summer: Annual precipitation (mm) < 20 × average annual temperature + 280
    • Else : Annual precipitation (mm) < 20 × average annual temperature + 140
    o If annual precipitation is < 50 % of the threshold = BW: desert climate
    o If annual precipitation is between 50 and 100 % = BS: steppe climate

    So the steppe climates can be more or less rainy if the evaporation is very high too. The same principle stand for colder climates too. They receive much less rain than hot climates but are still considered wet because the evaporation is much lower.

    (detail) Also, according to the classification, it's possible to have cold winters in BSh as long as the average yearly temp are high enough. Rare but possible

    (detail) BWn: it's an additional class for desert near water that have a small temperature variation like Namibia. I was considering incorporating it


    Csb:
    monthly temperature never go over 22, so it's not hot and not cold either because it never go below 0 (monthly)
    I just like to specify that Csc form usually at higher altitudes at it's not very common

    Cwb/Cwc: monthly temperature never go over 22, so it's not hot and it's even colder for Cwc, they are located at higher altitudes

    Cfb: it pretty sure that the temperature rarely go under 0. And what do you mean by very wet ?

    Cfc: : it's hard to say because only a few places are said to have this climate. Like Reykjavik: the temperature difference are small and winters are cool around 0 degree.

    D climates: if I have the temperature right for the extreme cold, it should only be applied with : Dfd, Dwd, Dsd and the other colder climates. I tried to find other climates in the D group with winter months under -38 but I could not.

    Dfa,Dfb: you inversed the summer and winter precipitations.

  10. #30
      Azelor is offline
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    I admit that it's like a puzzle, there is a lot of elements you need to think at the same time. But even so, a puzzle always have pieces that have similarities and that you need to put one next to the other.

    I'll try to take a look at the map but do you have a detailed precipitation map ?

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