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View Full Version : The Köppen–Geiger climate classification made simpler (I hope so)



Azelor
07-23-2014, 01:03 PM
I see that lot of people have a hard time with their climates when they are creating their world. I'm not an expert, but I'm trying to make it simpler when it come to the climatic zones.

I used this as the main source of information : Köppen climate classification - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification)
But also other pages and some scientific articles. Sadly, I wasn't able to find the original version of the classification other than in german but I can't read it. From what I understand the information on the wiki seems pretty solid but also very confusing. The information is there (most of it) but it's not very easy to understand. The first part I did was to collect the info on the wiki and also elsewhere to get a clear definition for each climatic zone: what it is but also where to place them: where they are the most likely to appear. It ended in something relatively complex and a long document. I still have some questions so I would like if someone could tell me what he thinks about it. By trying to make things simpler yet accurate I fear that I might be missing the boat.


Things left to do:
Find if others fantasy climates are possible
And possibly making some table/graphic

Questions :
Is the description of the climates ok ?
Temperature in degrees or by category?
East and west: is it possible to have it the other way around?
Wiki Color scheme wrong? it could be improved
Easy to understand?
would some infographiccs make it easier ?
[INDENT]I was considering making a map with the different latitudes of each climate, where they are usually located.
A graphic showing the maximum temperature yearly and by seasons for summer and winter (I just need to be sure my numbers are ok)
Make a table with climate characteristics (like in page 6 but with more info)
a graphic like this with the description of the climates but also for the individual letters. They could be all side by side. like this:

Azelor
07-23-2014, 01:19 PM
My main goal was to find if there was a link between the climate and population density. And if so, to find what density would be for one specific climate.
I realized I had a serious issue with a state with similar climate to India and somewhat similar size but the population was about only 9 millions people. I did not make sense and I had no answers how to get population density numbers right.
I also happened to have no clear idea on where to place the climates. That's why I'm doing this, and hopefully I can work on the second part after this one is finished.

But I admit that I'm not sure the population density numbers will make sense. We will see that later.

Iggy
07-23-2014, 01:31 PM
I tried to open the file but OpenOffice tells me it's damaged. Does that document come in any other format?

Azelor
07-23-2014, 01:35 PM
It's a .doc
I will replace it with a pdf

Iggy
07-23-2014, 01:37 PM
OpenOffice Writer can read and write .doc files just fine. Except for this one.

Pixie
07-24-2014, 09:42 AM
I've read the whole thing, it is helpful indeed Azelor.

Being a science teacher and an amateur climatologist/geologist (in fact, an amateur world-builder), I can follow all of it pretty easily. Dunno how less science savvy folks will manage it, but it doesn't seem complicated.
I think it is a very valuable add-on to the tutorial I (we) are currently building.

It made me think of one more climate map that would be very useful: a cross-reference between rain pattern and temperature, to make a two-colored map separating areas where evapotranspiration is greater / lower than precipitation. This could perhaps be helpful (do you think it would be helpful?)

Picking up the word usage in my tutorial, what do you think of this?
Lower precipitation than evaporation (DRY seasons)
Very Hot + Moderate/Low/Dry
Hot + Low/Dry
Warm + Dry
Roughly equal precipitation to evaporation (MODERATE seasons)
Very Hot + Wet
Hot + Moderate
Warm + Low
Mild + Low
Cold + Dry
Very Cold + Dry
Higher precipitation than evaporation (WET seasons)
All remaining combos

Corvus Marinus
07-24-2014, 11:32 AM
Breaking down the meaning of each of the letters is really helpful in understanding the details of the system. And I think Part II: Climate Zones will be very useful; it's a lot clearer than Wikipedia. The formulas in Part I, for me (not very science-literate), do not translate into immediate usefulness in worldbuilding; but I can easily take Part II and use it to "proof" my map after it has gone through Pixie's system.

If I am still around when you have a final draft, I will happily check it for spelling/grammar/formatting, if that is something you'd appreciate.

Azelor
07-24-2014, 06:01 PM
I've read the whole thing, it is helpful indeed Azelor.

Being a science teacher and an amateur climatologist/geologist (in fact, an amateur world-builder), I can follow all of it pretty easily. Dunno how less science savvy folks will manage it, but it doesn't seem complicated.
I think it is a very valuable add-on to the tutorial I (we) are currently building.

It made me think of one more climate map that would be very useful: a cross-reference between rain pattern and temperature, to make a two-colored map separating areas where evapotranspiration is greater / lower than precipitation. This could perhaps be helpful (do you think it would be helpful?)

Picking up the word usage in my tutorial, what do you think of this?
Lower precipitation than evaporation (DRY seasons)
Very Hot + Moderate/Low/Dry
Hot + Low/Dry
Warm + Dry
Roughly equal precipitation to evaporation (MODERATE seasons)
Very Hot + Wet
Hot + Moderate
Warm + Low
Mild + Low
Cold + Dry
Very Cold + Dry
Higher precipitation than evaporation (WET seasons)
All remaining combos

Good to know.

Were you considering a map or some info graphic like this one : http://powerfulinfographic.com/wp-content/uploads/2011/10/transparency-11.jpg
I don't know about the idea. There is a relation between temperature and minimum precipitations to avoid desertification. Did you know that the Sahara would need between 3000mm and 6000mm of rain per year to become a moderate climate similar to Spain? That's a lot of water and it's just the minimum.

There is a part in the guide where I talk about yearly precipitation not seasonal. The problem with the classification is that it compares the driest month with the wettest without taking in consideration if the driest month is really dry. Sometimes, it's not the case. It's considered dry only because the wet month receive a lot more rain. So the letters s and w are more or less valuable here. At the equator, at least we know that under 60mm it's considered dry.



edit : this ! http://en.wikipedia.org/wiki/Aridity_index

and this : http://upload.wikimedia.org/wikipedia/commons/c/cc/K%C3%B6ppen-aridity-index.png

Azelor
07-24-2014, 06:13 PM
Breaking down the meaning of each of the letters is really helpful in understanding the details of the system. And I think Part II: Climate Zones will be very useful; it's a lot clearer than Wikipedia. The formulas in Part I, for me (not very science-literate), do not translate into immediate usefulness in worldbuilding; but I can easily take Part II and use it to "proof" my map after it has gone through Pixie's system.

If I am still around when you have a final draft, I will happily check it for spelling/grammar/formatting, if that is something you'd appreciate.


I got the idea and some of the info from the french page of the wiki. But I think some info were not 100% accurate. It's hard to tell since I made a lot of modifications+translation to english. Talking a'bout spelling, I have no doubts that there is room for improvement. Thing I did not know: the rules for capital letters in english are very different from french.

Azelor
07-26-2014, 01:03 AM
Hey, I got some numbers!

Replacing this :

• 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

by this:

if the annual precipitation (in centimetres)

are Greater than R= humid
are Smaller than R but greater than R/2= semi-arid
are Smaller than R/2= arid

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




Examples:
Biak Indonesia (climate Af) precipitation = 284 cm: T= 27
R=2 x 27 + 14
R= 68
R/2= 34
284 is greater than 34, therefore it’s a humid climate (that is really wet)

Let’s try with Rome (Csa) T= 15,2 /precipitation 80,4 cm
R=2 x T
R= 30,4
30,4 is greater than 15,2 = humid

Los Angeles (Csa) T= 17,8 precipitation: 45,2
R=35,6
45 is greater than 35,6 but it’s much closer (R= 38 downtown LA partly because large cities tend to influence climate)

Tehran BSk (semi-arid): t=17 precipitation = 23
R=34.
23 is smaller that 34 but larger than R/2 so it’s semi-arid

I tried with Tabriz (also BSk) and it was considered humid !

Pixie
07-28-2014, 10:01 AM
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)

Azelor
07-28-2014, 07:34 PM
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.

Pixie
07-28-2014, 08:15 PM
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...



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.

Azelor
07-29-2014, 08:38 PM
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

Pixie
07-30-2014, 05:41 AM
Table isn't finished, but here's what I mean:
6614266143

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.

Azelor
07-30-2014, 11:49 AM
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

Azelor
07-30-2014, 12:15 PM
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.

Pixie
07-30-2014, 05:25 PM
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.

Azelor
07-30-2014, 06:13 PM
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.

Pixie
07-30-2014, 06:54 PM
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?

Azelor
07-30-2014, 08:01 PM
You are perfectly right. The extremes can be combined together without having a great impact. At 20mm per month, you might have some scarce cacti and some lichen. I thinks it's still considered as a desert.

1: 0-10
2: 10-20
3: 20-40
4: 40-80
5: 80-160
6: 160-320
7- more than 320

1: 0-20
2: 20-40
3: 40-80
4: 80-160
5: 160-320
6- 320-640
7- more than 640

1: 0-20
2: 20-40
3: 40-80
4: 80-160
5: 160-320
6- more than 320

or another combination with 7 categories

I'm not sure what we are doing right now. It is very interesting but I'm not sure what our goal is.
The things is, using the basic Koppen classification, s,w and f are distinguishable only with the difference in precipitation between the seasons. The overall precipitation does not matter, neither does the evaporation ratio. They matter only if you want to know if it's humid, semi-arid or arid on a yearly basis.

Azelor
07-30-2014, 09:23 PM
My idea was to use the average temperature of a climate to find the required level of precipitation in order to have a humid climate following the R=2T... formula.

Example:

Dsb:


D. Continental climates
• Average temperature of the 3 coldest months < 0 °C
• Summer and winter season are well defined
s. Dry summer
• Combined with D : driest summer month < 30 mm and < 1/3 of the wettest winter month
b. Temperate summer
• Average temperature of the hottest month ≤ 22 °C
• Average temperature of the 4 hottest month > 10 °C
Combined with D : driest summer month < 30 mm and < 1/3 of the wettest winter month

Dsb: Warm Continental Mediterranean
• Precipitations: moderate
o Summers = dry
o Winters= wet
• Average monthly temperature between -25 °C and 22 °C
o Summer: mild to warm
o Winter: very cold to cold

there are 4 thermal possibilities with this one:
This is the average of the average monthly temperature of the hottest and coldest months

Mild summer, cold winter (14/-5)
Mild summer, very cold winter (14/-17,5)
Warm summer, cold winter (20/-5)
Warm summer, very cold winter (20/-17,5)

now I was wondering, your a science teacher so you probably have a better understanding of this than I do.
Based on observations the climate usually do something like N=2 : File:Dice sum central limit theorem.svg - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/File:Dice_sum_central_limit_theorem.svg)
So we can agree that the climate follow a linear progression toward the year. (Another assumption)
For example this temperature distribution:
8,10,12,14,16,18,20,18,16,14,12,10

The average is 14, the same as 8+20/2
so, with the average monthly temperature of January and July, we can easily find the yearly average temperature, right? And if so, does it make things simpler from your point of view?
(or maybe you already figured that out long ago and I'm just making a fool of myself :mrgreen:)


For precipitations, the < 30 mm and < 1/3 could be changed to something else to make it fit with the categories, otherwise as you said, it becomes impractical.


The problem with the precipitation is that you only have a snapshot of it, one in January and the other in July. I'm not sure how this info can be used to determinate the overall wetness of the climate. Do you have any ideas?

Proposition:
if it's f: take average precipitation of the category, multiply by 12, since the variation is small and it's all about the average. example: 80-160 (120 on average) becomes 1440mm
if it's s or w, take average precipitation of the category. multiply the January precipitation by 6 and July precipitation by 6.
(I just tried this on several cities, taking the closest category average, and my yearly numbers are pretty close to reality)

example: 0-10 (average 5) and 40-80 (average 60) (5x6)+(60x6)=390mm

So let say I have a Csa climate


• Precipitations: moderate
o Summer: dry
o Winter: wet
• Average monthly temperature between 0°C and 35 °C
o Summer: mild to very hot
o Winter: cool-mild

with a warm summer: 20 on average
with a mild winter: 14 on average
yearly average: 17

R=2T
R=340mm
This is the minimum precipitation required to have a humid climate. It's good because we have 390mm, just enough.

so to make this fit into your graphic:


January: mild/category 4
July: warm/category 1


I'm not sure I understand what the humidity column is about. Because as I said earlier, it's more relevant when it's on a yearly basis unless I'm missing something.

Azelor
07-31-2014, 01:05 AM
Also, I think you are miscalculating the possibilities.

The 2 desert climates are always dry (0-20) or maybe could go a bit above that
Af: precipitation are always very wet (almost)

Some climates have only 1 or maybe 2 possibilities for a specific season
Example: Aw and Am must have a wet or very wet summer
Cwb/Cwb: are dry in winter (almost 0 rain)
Cwa is never dry even in the dry season.

etc...

that reduces the possibilities but it's still a lot.

I also made some modifications in order to only take into account the hottest month, not the whole season like it was before. Again, it reduce the temperature range of several C and D climates. That is what I got:

Arid:

Bwh:
• January: mild, warm, hot
• July: hot, very hot, severely hot


Bwk
• January: Very cold (rare), cold, cool
• July: mild, warm, hot

Semi arid

Bsh
• January: mild, warm
• July: hot, very hot

Bsk
• January: cold, cool
• July: mild, warm, hot


Humid :
• Af : warm, hot, very hot
• Aw: warm, hot, very hot
• Am: warm, hot, very hot
Csa:
• January: cool, mild
• July: hot, very hot
Csb:
• January: cool, mild
• July: mild , warm

Cfa:
• January: cool, mild
• July: hot, very hot
Cwa:
• January: cool, mild
• July: hot, very hot
Cfb:
• January: cool, mild
• July: mild , warm
Cfc:
• January: Cold, cool
• July: cool, mild
Cwb/Cwc:
• January: cool, mild
• July: mild, warm

Dfa:
• January: cold,cool
• July: mild, warm, hot
Dwa:
• January: cold,cool
• July: hot
Dsa:
• January: cold,cool
• July: hot

Dfb:
• January: very cold, cold
• July: mild, warm
Dwb:
• January: very cold, cold
• July: mild, warm
Dsb:
• January: very cold, cold
• July: mild, warm

Dfc:
• January: severely cold, very cold, cold
• July: mild, warm
Dwc:
• January: severely cold, very cold, cold
• July: mild, warm
Dsc:
• January: severely cold, very cold, cold
• July: mild, warm

Dfd:
• January: deadly cold, severely cold, very cold
• July: cool, mild
Dwd:
• January: deadly cold, severely cold, very cold
• July: cool, mild
Dsd:
• January: deadly cold, severely cold, very cold
• July: cool, mild
ET:
• January: severely cold, very cold, cold
• July: cold, cool
EF:
• January: Deadly cold, severely cold
• July: severely cold, very cold, cold

I hope we will be able to simplify this because I have already 131 possibilities and that is just for the temperatures, not the precipitations. But it covers all the climates.

Some of them like the tundra can have any precipitation level. And the ice cap receive no rain, so we could discard them right now because the precipitation is not a important element for them. I'm left with 119 possibilities.

Pixie
07-31-2014, 06:24 AM
This post got me thinking about how short is a 6 tier classification for mean temperature... You are using 11 different ratings in this and yet, there are some temperature combos present in more than one kind of climate, which means it becomes useless for classification means if there isn't more information as the same temperature range can be found in two of the climates...

So I thought the way to counter this sort of lists where we get confused is to use a 2-entry table. So I sat down and made one, I went for an 8 tier classification, including your terms "cool" and "severely cold". More than 8 is too much in my opinion.
So this is it. This table would be the source for classifying the entire thing according to temperature (precipitation/humidity) would come at a later stage.

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question 1:
what do you guys think of the use of a 2-entry table?

question 2:
and what about the actual key used to fill in each position?

note:
cold deserts and cold steppes are a miss in this table, as their temperature ranges would be more in the tune with a D-climate - they would have to be determined separately.

note 2:
instead of terming the table X/Y axis as july and january, it could be termed as hottest month vs. coldest month, and then the classifications in each position wouldn't have to be symmetrical, allowing more flexibility - but at the same time, doubling the workload for the user, as it meant working the two hemispheres in separate.

Azelor
07-31-2014, 12:18 PM
I do like your table, it look simple and clean.

The keys look alright to me so far.


To get rid of the problem with the 2 hemisphere having the summer and winter seasons at the opposite, climatologist use ''high sun'' (summer in that hemisphere) and ''low sun'' (winter in that hemisphere). It doesn't really change that the seasons are opposed, so the cartographer will need to consider this. Did you took this in consideration with Palamb? I admit I did not.

But the difference is almost inexistent at the equator.

note2: as said earlier I was suggesting the assumption that January and July are always the coldest and hottest months. Even if it's not always exactly the case, it is never really far.



I'm gonna go back at the precipitation topic a little. It's too complicated and even if we try to simplify it, only scientist and masochist will what to use it.
I need to go back to what I said initially that was : when climates get colder, less precipitations are require to stay wet.

We have that formula: Precipitation= temperature/2 (+something)
So, every time you move by 2 temperature categories, the minimum rain required move by one
In photoshop, this could translate in having another layer. The original if for the total precipitation, we don't change that. The second and new layer is a modifier added to the original. It take in consideration that more rain is required in hotter climate to stay wet. The first serves only as a reference representing total precipitations and the second represent the ''wetness level'' or ''relative precipitation''?
It could be done by making colder climates appear wetter using the same color scheme as the original.

here's what I mean:
All these places receive the same amount of precipitation
the categories are just placeholder

Temperature of the month/ total Precipitation / wetness level


cold/ humid / humid /
cool / humid / humid/
mild / humid/ sub-humid /
warm / humid / sub-humid /
hot / humid / semi-arid/
very hot / humid / semi-arid/
super hot/ humid / arid/

I don't go below cold because the evaporation is almost 0 at that point so it's a good place to start.

What should we use for precipitation level?

if I use the holdridge precipitation on the right combine with a possible equivalent on the left.
very wet/ super humid
wet/ per humid
moderate/ humid
steppe?/ sub humid
steppe/ semi arid
steppe/ arid
desert/ per arid
desert/ super arid

Pixie
08-01-2014, 10:00 AM
We have that formula: Precipitation= temperature/2 (+something)
So, every time you move by 2 temperature categories, the minimum rain required move by one

It doesn't. It is a linear relationship, it changes the scale (temperature and precipitation are measured in different units anyway), but not the progression. The graphs you showed earlier (temperature vs. precipitation) had that straight line. Twice as much temperature requires twice as much precipitation for the same level of "wetness".



In photoshop, this could translate in having another layer. (...) . The first serves only as a reference representing total precipitations and the second represent the ''wetness level'' or ''relative precipitation''?

That's what I was trying with the "available humidity" map and the column called "humidity" in that reference table. Still, I admit having only arid/semi-arid/humid is too short to accurately classify climates - it's well enough to determine deserts but insufficient for anything else.



What should we use for precipitation level?

if I use the holdridge precipitation on the right combine with a possible equivalent on the left.
very wet/ super humid
wet/ per humid
moderate/ humid
steppe?/ sub humid
steppe/ semi arid
steppe/ arid
desert/ per arid
desert/ super arid

I'll try to come up with a second 2-entry table adding up mean temperature and precipitation pattern. I mean, if I understand your idea (and if this is it I am for it), we will have three maps:
1. mean temperature
2. precipitation pattern
3. "wetness level" / "available humidity" / "humidity" (pick your preferred denomination, I vote for "humidity")

Climate regions would then be determined by finding particular combos of mean temperature and humidity.

Azelor
08-01-2014, 12:17 PM
You are right, I have the wrong numbers.

In words: On a yearly basis, an increase of 1 °C require an increase of 20mm (2cm) in precipitation in order to stay humid. (prevent from becoming a steppe)

But yea, the progression is erratic but maybe we could find a good way to scale it?


That's what I was trying with the "available humidity" map and the column called "humidity" in that reference table. Still, I admit having only arid/semi-arid/humid is too short to accurately classify climates - it's well enough to determine deserts but insufficient for anything else.
it's also helpful to determine steppe and humid climates.

Deserts include BWh,BWk and ice cap
Steppe:BSh,BSk,
Humid : everything else
Tundra can be anywhere

As for the rest, on a yearly basis the variation in precipitation can be large inside the same climate. the Koppen classification gives more importance to the precipitation pattern than the quantity of precipitation. By searching on the Internet, I saw many people complaining that some cities received 3 times more rain but were still classified in the same climate. My numbers confirmed that and I saw some researchers trying to solve the issue. They ended up adding subcategories...
I always thought that the Mediterranean climates were dry. While some are close to become steppe (southern Spain) some receive quite a lot of rain like Porto.

So as long as we use this classification, we got to use these 3 categories (arid/semi-arid/humid). Otherwise we will have the modify most of the categories.



I'll try to come up with a second 2-entry table adding up mean temperature and precipitation pattern. I mean, if I understand your idea (and if this is it I am for it), we will have three maps:
1. mean temperature
2. precipitation pattern
3. "wetness level" / "available humidity" / "humidity" (pick your preferred denomination, I vote for "humidity")

Climate regions would then be determined by finding particular combos of mean temperature and humidity.

Yes something like that. The precipitation maps are just temporary.
And you mean ''mean temperature'' for the whole year or hottest/coldest month only ?

Azelor
08-01-2014, 12:59 PM
I made a table that might help you. It have the mean temperature for the hottest/coldest month based on the average for each categories. And the mean annual temperature.
The formulas are explained in the top.

There is also a column for minimum precipitation for each possible combination.

I'm not sure the formula for the annual temperature is ok. It's supposed to be an approximation.


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Pixie
08-03-2014, 05:22 PM
Great effort there, Azelor. That will help a lot in developing that reference table I mentioned earlier. I am still most worried with the sheer number of possible combinations...

But, I thought of a possible solution. This is a question for expert PSP/Gimp users, as well... If there was a way to set up a filter, in photoshop, that would do a look up based on the color of a pixel in different layers and paint the result of the lookup in a separate layer (did I explain myself in a legible way?) - then we would automate a part of the process.

I mean, automating this tedious task:
- if #color in layer "january mean temperature" is X and #color in layer "january precipitation" is Y and #color in layer ".... (etc.) then #color in layer "CLIMATES" becomes ZZ.

Azelor
08-03-2014, 07:38 PM
what your looking for is probably a script. But I know much about that.

Pixie
08-03-2014, 07:43 PM
Well, if it is a script, a script it is. I might google for a "how-to" later on. But first need to work on that table..

Azelor
08-03-2014, 08:09 PM
I did a small correction to my last table. Apparently I used the average to calculate the boundaries of each categories...
here I used the min/max, it's more logical
good numbers are in parenthesis

cold 0-70 (0-140)
cool 70-240 (140-340)
mild 240-420 (340-500)
warm 420-540 (500-580)
hot 540-640 (580-700)
very hot 640-770 (700-840)
super hot 770-900 (840-940+)

Azelor
08-08-2014, 09:55 PM
Hey Pixie I got an idea

the classification your trying to make have 4 parameters right? Otherwise 2 parameters are useful only if you take in account the yearly temperature and precipitation. But we have 2 seasons so we need 4.

I think we could do that with colors. Every combination would have it's own resulting ''color''.
For that, we won't be using the RGB system but the CMYK.

more or less:
Cyan-summer temperature
Magenta- winter temperature
Yellow-summer precipitation
Key (black)- winter precipitation


Temperature: My classification has 10 levels of temperature:
Cyan and Magenta in percentages:


Severely hot: 100 %
Very hot: 90 %
Hot: 80 %
Warm: 70 %
Mild: 60 %
Cool: 50%
Cold: 40 %
Very cold: 30 %
Severely cold: 20 %
Deadly cold: 10%


Precipitations: I still need to decide the categories but I'M going to use this as an example:
Yellow and black in percentages


0-20 mm: 20 %
20-40 mm: 40 %
40-80 mm : 60 %
80-160 mm: 80 %
more than 160 mm: 100%


example:

Milan, Italy (Cfa)
Temperature in summer: over 22 = hot
C= 80 %
Temperature in winter: below 10= cool
M= 50 %
Precipitation in summer: 40-80 mm
Y= 40 %
Precipitation in winter: 40-80 mm
K= 40 %

Milan
color=#1e3c37

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I don't know what you think about this but the precipitation part is useless without good categories. But when you have the precipitation level you know what are the minimum rain requirement for each temperature categories. In Milan case, it's humid all the time since the average is 78 mm per month. Another place with same temperature but a drier winter would have a different resulting color. The percentage of Y or K would indicate what's dry depending on the rest of the combination.

I'll try to make a table.

Azelor
08-09-2014, 01:03 AM
all possible combinations !
also include some very unlikely possibilities. According to my previous excel document, only 39 of the 100 temperature combinations are possible. Those that are not are inside the gray border.
So it's something like 975 and probably less because some temperature and precipitation combos are impossible. Such as very cold with a lot of rain.

Have fun !

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Azelor
08-09-2014, 12:21 PM
I'm going to bring some corrections because ,

Problem 1: when the blacks are too strong, Photoshop cannot separate the different colors. The square appear black but the level of CMY are not always the same. So I lowered the black : 90%,80%,70%,60% and 50%.
He is still mixing the colors in some rare cases where the borders are not 100% accurate but otherwise it look fine.

Problem 2: the magic wand is not good enough. I have to use another selection tool : SELECTION/COLOR RANGE
the result are much more accurate

Problem 3: I'm not sure I can use Jpeg (or another normal image file) for this because the colors need to stay the same. There is room for slight alterations but not so much.


Now the good part !:
less possibilities!

if I take the bottom of the temperature graphic, what i call thermal possibilities. Out of the 100 possibilities, only about 37 (before it was 39) of them exist on Earth. For the precipitation I'm pretty sure that all the 25 combinations are possible, with a grand total of 925.
But then you combine the temperature and precipitation. Some combinations are again, not possible. (Or extremely unlikely)
I do admit that in a fantasy world it is possible to have a deadly cold summer with an even colder winter but this means that the temperature rarely go over -38. No one can live there and the precipitation pattern is identical to severely cold.


Severely cold summers only have 2 possibilities in winter: severely cold and deadly cold. That is the eternal snow and ice climate. It's a desert so they only have the driest precipitation possibility for both seasons (between 0 and 20mm in this example)
so they only have 1 of the 25 precipitation possibilities. So the total possibilities for them are not 2*25=50 but 2*1=2

Very cold summer is in the same situation but the precipitations in summer could be a little higher (I'm not sure) but the only place to have very cold summer is again the ice caps. Very cold winters could have higher precipitations but it's another case. possibilities are: 2*1=2 (same as above)

Cold summer: I made a mistake: tundra can't have a cold summer. So again we are stuck with just the ice cap. as above, only 2 possibilities



With these 3, I just eliminated 144 possibilities with 781 to go.
Ok they are the most extreme but I will see if I can get this to be useful.

Pixie
08-09-2014, 08:09 PM
I like your idea.

We would need to have a key "color to climate type", wouldn't we?

I'm off on holidays in a couple of hours, but will get back to this in September. That is, if you didn't fully solve the problem by then.

Azelor
08-10-2014, 04:20 PM
yes some color key. You see, I already have ET and EF done. They have their specific colors, 6 each that are unique to them. But other climates are generally more complicated.
What I did was to look at the temperature combos and place the climate zones in the graphic. I did the same thing for the precipitation but now I need to association each temperature combo with the possible rain pattern. Or something like that.
I have been able to find some BWh that have a unique termal color but most of them are in the sames categories as other climates. They usually have different rain patterns so we can split them with that criteria but it is not always the case. So, it the end you have some climates that have the same temperature and same rain pattern. In some cases, it's not possible to associate a specific temperature with a specific rain pattern. So even if I try to clean it up, some climates will get stuck together.

Most of the mixes are not so bad such as having the Dc and Db on the same temperature spot. The second letter (fsw) will change but the limit between the b and c zones need to be established by the mapper. The lower half is b and the rest is c.
But it is also possible that some climate are not well categorized...

Setting apart the humid, steppe and desert is easy if you go with each temperature combo alone. To make this, I will probably need to do a smaller version on the graphic for each of these possible temperature combos.




Have a nice holiday!

Azelor
08-11-2014, 02:31 PM
This is what the simplified color table look like right now, and it's not finished. There is around 350 possibilities. Climates that are possible on Earth but other combination are possible, I will ignore these for now.
Apparently, 4 of the 25 rain pattern do not exist with any climates. This is probably due to the fact that humid climates (f) are located in the central axe, winter dry is above and summer dry is under. Since dry season do not have a lot of precipitation, no suitable climates are found in these categories. I guess it's not really a problem.

White squares: they could exist but they are generally more extreme than Siberian climates. If you have a very large continent not too far from the pole (larger than Asia) or have a bigger planet tilt, you might encounter these climates.
Magenta (pink): thta is too hot: the temperature rarely drop below 30 degrees.
Too cold: colder than Antarctica: temperature rarely go above -38.
Grey: while they do not seems to exist (or maybe I just lack of informations) I think they are plausible. With cold (but not extreme) temperature but a small annual variation. Maybe at high latitudes close to the sea or on high tropical mountains.

This grid is temporary so the colors you see are probably wrong. I can't use JPEG because the file is not in RGB. The forum automatically change the colors to RGB when I upload it. But this is not the final edition.
every climate will have his own colors in time, but some could share the same color. I will try to limit this number to 2.

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I see several problems:
1- it is possible to make some area colder in the summer that winter (by mistake) this should not happen
2- it is possible to get a combinations that is not in the table, when all other areas are categorized, I guess it's easy to take care are these. But the mapper will have to figure it out.
3- some climates fall exactly in the sames categories. Like Dsc and Dsd, but their temperature are supposed to be different. The system got rid of that difference so my solution is to try to find a balance. Climates thta are a little colder will be categorized Dsd and hotter ones will be Dsc. I will do the same thing with precipitations.
4- some climates are considered humid even when they are in the lowest precipitation square. I'm not sure what to think about this because it could end up having a lot of climates there.
5- Aw and Am look exactly the same, I'm thinking about fusing them together. One of them receive slightly more rain but the impact is small.

I'll stop there because I'm probably speaking to myself...

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And that is the result so far with 1/7 left to classify.

Azelor
08-15-2014, 03:22 PM
update: some progress

Most of the climates make sense now except the steppes. I don't know where to place them.
Each block of blocks represent 1 rain pattern. Generally, the top left is hot and the bottom left is cold. So, if all receive the same precipitations the driest should be in the top left...

in order to keep the steppes in these areas I need to move them to the top left but if I do so, they usually fall in a place too hot for them. So either:

The top left become a desert, middle is the steppe and bottom right= humid
or I just get rid of the steppe, maybe it's not possible to have that there.

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Azelor
08-25-2014, 02:04 PM
I got the color key, but I haven't tested it yet. I will do it very soon.

Climate tutorial version 1:

color reference file:

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Several assumptions about climates to make thing simpler:

1- July is always the hottest month is the north and the coldest month in the south.
2- January is always the coldest in the north and the hottest month in the south.
3- Some places close to the equator might have a summer temperature colder than their winter temperature. It’s possible if the difference is small. If you encounter this elsewhere, it’s not normal unless you have a very particular microclimate. The color scheme won’t tell you about this issue.
4- I assumed that the temperature variation was constant throughout the year. So if some place has an average temperature of 6 during the coldest month and 12 for the hottest month, the monthly temperature variation is 1.
5- Precipitations map represent the precipitation for a specific month. Yearly precipitations are estimated as follow:

a. If July and January are inside the same precipitation category or only one category apart, the area is considered to receive the same amount of precipitation all year long. Letter f.
b. If the difference between the precipitations of July and January is more than one category apart, the area is considered to have one dry season. If the dry season is the hottest; the letter is s, if the dry season is the coldest; the letter is w.
c. Take note that these 3 letters: s,f,w; doesn’t tell you if the climate is either humid, semi-arid (steppe) or arid (desert). It’s just about the precipitation pattern.

Also, I used 10 levels of temperature, it’s more than Pixie. I use 10 because they are necessary to differentiate some climates. If you don’t have 10, it might cause problem.


Info about color key

You need to work in CMYK for the scheme to function properly. You don’t need the whole map to be in this mode, just the relevant layers. I tried to make it in RGB mode but I could not get a good combination. Most of the time, several climates had the same color, rendering it useless. The ‘’color key’’ is obtained by combining the Cyan (hottest month temperature), Majenta (coldest month temperature), Yellow (hottest month precipitation) and black (coldest month precipitation).

Before starting, you need several layers. You should already have them if you followed Pixie’s tutorial.

1- July temperature map (Summer of the northern hemisphere, winter in the south)
2- January temperature map
3- July precipitation map
4- January precipitation map


0- Create a new file by selecting CMYK as the color mode. Or you can also use the file containing the other layers as long as you make sure that the file is in CMYK, very important. Import the file named ‘’color reference’’.

a. Take the table I made and put it in the same file. You need to make sure that the elements of the table do not overlap with your landmasses otherwise you will miss these parts. So either put the table over an empty spot, at the poles or the ocean, or aside from the map.


1- First thing you need to do is to make sure your precipitation maps only have 5 levels of rain possible so you need to fuse the highest levels of rain. To do that, select the first 4 categories with the magic wand and use inversion. This should select everything that is not inside the 4 first categories. Paint it in the same color as the very wet category.
Why? Past a certain amount, the precipitation stops to have an impact on the climate. This is according to the Koppen classification, because the tourist agency could think otherwise.


2- Temperature maps: You can use the maps you already have. You will need to change the colors.

a. July temperature layer should be paint using Cyan only. Use the colors from the table.
b. January temperature map uses Magenta only. The exact values are as follow for cyan and magenta. To make these two maps, you need to paint the temperatures using the specified colors. One in cyan and the other in magenta. Make sure you only use one of the four colors per layer.

Severely hot: 100, Very hot: 90, Hot: 80, Warm: 70, Mild: 60, Cool: 50, Cold: 40
Very cold: 30, Severely cold: 20, Deadly cold: 10


3- Precipitation maps: Use the values of the table.

Sadly, you will need to make 2 versions of both precipitation maps. One version of the maps is for the north and the other is for the south. The reason you need to do it separately is that the impact of the precipitations on the environment depend if they fall during the cold or the hot season. You need more to keep the area wet if it falls mostly during the hot season.

To make the map, start with the north, with the July precipitation map. Change the previous colors to the appropriate colors in yellow. Do the same process with the January precipitation map but using the blacks. You will need to stop at the equator.

For the south, you will need to use black for July since it’s the cold season in the south. And use the yellow for the January precipitation map. Make sure the north and south layers don’t overlap past the equator. So in the end, you have the July precipitation with yellow in the north and black in the south and the January map with black in the north and yellow in the south.

If it’s easier, you can also use different layers for north and south with a total of 4 layers. It the end you still need to merge them.


a. Summer precipitation: paint in yellow. Here are the values.
Very wet: 95, Wet: 73, Moderate: 51, Low: 29, Dry: 7
b. Winter precipitation: Paint in black. Here are the values. The last one is different from the Yellow one. It’s because the magic wand could not select the last category correctly. It was too pale.
Very wet: 95, Wet: 73, Moderate: 51, Low: 29, Dry: 18

***This part might need adjustments, since it might give weird results)


4- Now take you 2 sets of precipitation maps. Set one under the other (doesn’t matter which one) and the other above set to multiply mode. Now you should duplicate these layers and merge them. By doing so, make sure that it keeps the same colors (just to be sure). This will get you the precipitation pattern map.


5- Now, you won’t keep all the categories. Some precipitation patterns contain the same climate zones. It makes no differences if we ignore them and it lessens the possible combinations. So you will merge some of them. Look at the table at step 5 and follow the arrows. Select these colors from the precipitation pattern map and paint it into the new color. This will give you the final precipitation pattern map.


6- Layer placement to get the color key:

a. The precipitation pattern map is placed at the bottom in normal mode
b. Then, the magenta layer set in multiply mode
c. Finally, on top of all, the cyan layer is in exclusion mode

Now I would recommend that you duplicate these layers and merge them into one layer. Make sure you keep the same colors. Name it ‘’color key map’’.
This should produce a color key with 1000 combinations. Well not really, in fact, it’s more than 1000 but we can simplify it. You see, for the coldest temperatures, the precipitations are irrelevant so:


7- Create a new layer for the climates. I recommend putting all the different climates on a different layer each.

a. Using only the temperature layer paint the ice caps and tundra climates, see their colors at the top of the reference file. tO DO THAT YOU NEED TO HAVE ONE OF THE TWO LAYER IN MULTIPLY MODE AND SELECT MORE THAN ONE LAYER WITH THE MAGIC WAND.

Using the magic wand, only keep useful layers visible. Set the wand to be able the select all the layers and to be able to select multiple object one after the other (add to selection). Make one climate at a time and select all the corresponding colors on the table. This will also select the colors of the color key map at the same time. After each color are selected for one climate, paint it in the climate layer.

Start with the ice caps by making only the temperature layer visible (not the precipitation layers). And do the tundra after that. When they are done, make the precipitation map visible. You can proceed with the other climates.

Each climate has a certain number of colors. Some have more than other but it does not mean they are more frequent. Some also have the + next to them, especially the coldest D climates. D climates are already extreme, but this is even more extreme. Some have 80 Celsius in difference between the mean temperature of the coldest and hottest month. The maximum on Earth is closer to 60 Celsius. These climates are not impossible but very unlikely. They are usually found far from the ocean at high latitudes like Siberia but the conditions are more extreme. To have these, the planet probably needs to have a bigger axial tilt and since this tutorial is mostly about Earth-like climates, I consider them unlikely to happen. They can be ignore or left out for later to save some clicking.

Note TO MYSELF: use 300 DPI
when changing RGB to CMYK, don't merge layers. The colors will change, it's normal and it can take some time if the file is large.
Last yellow is 29 but should be 7, need an update
Magic wand tolerance: 10 not lisse (not fuzzy ?)
Paint tool fuziness to 255
Part 3: 2 layers in total
start with july, select the north, to do that choose select all in the selection menu and modify the selection to only 50% of the file's height and select on squares at the top left that is in the top layer before clicking ok.
the ideal is to make a temporary layer with this selection, covering the top half with one flashy color. Put the dummy layer over the south to beging then move it north
do the same for the south but paint it in black, and make sure that all the layer is either black or yellow. If you forget something , you will miss some climates.
After this, do it for january with yellow in bottom and black on top.
Step 5: when selecting rain pattern reduce the tolerance of the magic wand to 0 or 1

That is all for now. I will update the tutorial later.

Azelor
08-28-2014, 01:16 AM
This is what the layers should look like. The forum usually convert the files from CMYK to RGB, so the colors are not the same if I use a Jpeg.

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66961

and with multiply:

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January rain
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July rain
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When you multiply them
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Precipitation map after step 5, the simplified version
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And when you combine all the layers, you get this !

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This is the rough climate map, the black climates are the one is the + sections. As expected they are really marginal so you can skip them. Other areas are missing near the equator, I will investigate. No so bad but there is a lot of mess.
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Azelor
08-28-2014, 02:55 PM
A couple of things that are questionable with the climate map. The method looks good but can be improved.

Cfa and Cwa (pale green) take too much space. Cfb is almost inexistent. That being said, outside of Europe, that climate is somewhat marginal. Should I make it more likely by moving some of the Ca colors into Cb ?

I'm not sure if it's normal to find the Dfc (green-blue) in the center of the largest continent. A lush pine forest dominating the surrounding steppes and cold desert... Not sure this make sense. It does look similar to Tibet and northern Mongolia.


And my last concern is about desert hot and cold vs the steppes. I think the steppes take too much space. Not so much but I think the north-est continent should be drier.
Desert: hot = red cold=pink
steppe: hot= orange cold=brown

On Earth, when it's hot almost 2/3 is a desert with only 1/3 steppe
when it's cold it's close to 50/50 for each

thought ?