WIP - My firts MAP - Photoshop

[Azélor]

No, I think you misunderstood.

The area near the equator is a low pressure. Therefore it is very wet. Very hot area makes the air rise and create an area of low pressure where the surrounding air masses converge with all the water they got from the evaporation over the water.
That low area is dragged over the continent in the summer bringing precipitation. In Asia it's called the monsoon. How far does it stretch ? Different sources indicate different latitudes. Manchuria is usually considered not affected because it is to close to the pole but it's climate indicate a strong difference in precipitation between the hot and the cold season. So it has a monsoonal pattern.

And something I just noticed is that the monsoon go much more toward the pole as is moves toward the east and I'm not really sure why. Is it an interference with the jet stream?

Your continent is quite big, as big as Asia? But unlike Asia, it has an ocean of cold water in the north. Meaning that the monsoon would not go as far in the north. In summer the low pressure would cover much of the continent south of the mountains and would bend toward the north as it moves to the east. Not too much, I don't think it could go further than the 30th of latitude.

---

your polar front seems alright for the summer. It covers a wide area because it's like a wave that is constantly moving.

---

The subtropical ridge will eventually almost ''dissapear'' as it reaches the eastern coast, where the polar front and the ITZC could meet only during the hottest months.

---

[Facubaci]

Hmm, okay. So how would it look?
Now I understand that the area near the Equator is a low pressure area. Very hot and humid area. And brings rainfall. That area goes over the continent in summer, giving rainfall at the south of it. North of the western mountains, would the wind be dry and a steppe-tundra climate? Would be a constant cold, dry wind from the pole to the Equator? And to the east, the "great lowlands" would be plains? Or the wet wind of Equator would leave the most rainfall in the mountains of southeastern?

Thanks, got complicated the issue, haha.

[Azélor]

In order to get the climates right it would be a good idea if you could tell what other landmass are around this continent. No need to be very specific but large landmasses will influence the climate.

WINTER

In Asia, the high pressure area (Siberian high) is located around the 50th parallel. Since your continent does not go that much to the north, the pressure should be much lower.

The winter ITCZ should be around the equator unless you have a large landmass in the south.

The zones between the ITCZ are in the Koppen classification: A. BW, BSh and also some Ca if I remember correctly. Areas thta are always very close to the ITCZ are usually the wetters. while those that are far will be the one with the most variation in precipitations. This is true for places located inland but not always for coastal areas and islands because they can receive rain because of their proximity to the oceans.

The polar front should follow a pattern like this:
http://www.google.ca/imgres?imgurl=h...d=0CEAQMygWMBY
http://www.google.ca/imgres?imgurl=h...d=0CEgQMygeMB4

it migrate to the south in the summer. Maybe until it reaches the 30 or 35th parallel.

The south, except some parts closer to the equator is now affected by the subtropical ridge. It's usually drier but that depends on the winds.

[Azélor]

Hmm, okay. So how would it look?
Now I understand that the area near the Equator is a low pressure area. Very hot and humid area. And brings rainfall. That area goes over the continent in summer, giving rainfall at the south of it. North of the western mountains, would the wind be dry and a steppe-tundra climate? Would be a constant cold, dry wind from the pole to the Equator? And to the east, the "great lowlands" would be plains? Or the wet wind of Equator would leave the most rainfall in the mountains of southeastern?

Thanks, got complicated the issue, haha.

It is possible but yes I think the summer is dry north of the mountains. It is too hot to be a tundra unless it's a high altitude. Possibly steppe, cold Mediterranean (central Turkey) or cold desert. The east would be much like north east america (Florida, Georgia, South Carolina) while the tip is more like New England.

I'll check that tomorrow but in the meantime you can take a look at this thread, we did the same processes: http://www.cartographersguild.com/sh...=27792&page=10

[Facubaci]

Oh, how complicated. Well, I have to say that there is a large island at the southwest of this great continent. It's far, and measures a third the size of this map. I can not draw a picture now, tomorrow yes. I don't think that island cares, it's like Australia, that it's far than Asia and in the other way (in the southwest).

My map has a middle-low pressure almost entirely. In the southern hemisphere there is no another landmass. And the areas from Ecuador to the parallel 30 or 35 ° would be tropical climate, wet tropical, warm steppe, desert, some Mediterranean climate at the west of the mountains between 30 ° and 45 ° and in the east would be like Manchuria (Dwa?).

The mid-continent area is bisected by a mountain, so in that zone would be mountain climate. And the other areas are relatively close to the coast.

Thanks for the the pictures of the polar front. But i thought that in summer the polar front can be retired near to the pole. Why it can reached to latitude 30? I thought that in winter the polar front should be very wide and narrower in summer.

I wish we can define the temperature of places together, because it seems too complicated for me.
I want to define the winds and where it rains more likely, as I tried to do in the photos above.
Thanks!

[Deadshade]

Another question about the map. The next step is the climatology. How can I define that? It's a fantasy world, but I want to continue with the realism; I thought the following items: the continent is located in the northern hemisphere, near to the northern pole. The south of the continent is close to the Equator line. I don't know how to define the winds, rains, forest regions etc without lose the logic. Can you help me?


!

Your problems are mostly due to the fact that you are mixing up the time scales. That's why it seems complicated even if it is not (for mapping purposes).

Climate is defined by long terme time averages like 20 years or more. The biomes (e.g the vegetation) depend mostly on these averages and not on all sorts of wild fluctuations that make up weather (short time scales).
To the long term averages add periodical events on smaller time scales which repeat over and over. Monsoons are an example of short term periodical event that repeats every 6 months but they are uninteresting for a map - the winds and precipitations would be different if you draw the map in winter or in summer. People rarely draw 2 maps , one for every season or 12 maps, one for every month.

So if your question is "Where grows what ?" what is a good question for a realistic map, you need really very few parameterss and do not need to worry about how the winds blow in winter or where are low pressures in October.

You start with temperatures : A good formula for average temperatures is : T (latitude, altitude) = a.cos(latitude) - 10.altitude (in km) + b where a and b are constants that you define by fixing the temperature at sea level Tp on a pole and Te on equator
(then we have b=Tp and a = Te -Tp).
With that you have the average temperatures at sea level on every point and from there at every altitude. You trace the 0°C isotherms which will give you the permanent snow and ice limit (e.g solving (Te-Tp) cos (x) + Tp = 0)
I supposed here a vertical rotation axis - it would be (slightly) more complicated if the axis had an angle with the orbit like the Earth.
Done.

Then you need precipitations. There is no handy formula so you may use an empirical linear dependence : maximum (in mm/year) at equator -> 0 at 25° -> half of equator amount at 45° -> 0 at poles. Precipitation depends then only on latitude which is consistent with the Hadley and other circulation cells I already explained earlier. You then only need to fix the precipitation at equator f.ex 3000 mm/year. Crude but sufficient.
Done.

You need nothing more. Now you'll use the Whittaker biome diagram (f.ex here : http://www.marietta.edu/~biol/biomes/biome_main.htm) and you have answered the question where grows what on the whole planet and can finish your map.


It is only, and I insist ONLY if you want to nitpick on details because you are curious and have time to learn quite complex things, that you'll break the precipitation symmetry and look at a few invariants like trade winds, mountain uplift and monsoons (but not much more !). This would introduce slight asymetries like f.ex having deserts more on western side of continents rather than eastern etc. But it wouldn't change fundamentally your map.

Another even easier way to break the symetry to which leads the simple but realistic model above is to slightly and randomly change the frontiers between biomes.
Nobody would notice anyway

[Azélor]

Oh, how complicated. Well, I have to say that there is a large island at the southwest of this great continent. It's far, and measures a third the size of this map. I can not draw a picture now, tomorrow yes. I don't think that island cares, it's like Australia, that it's far than Asia and in the other way (in the southwest).

Ok then I will suppose the impact of the ITCZ is minimal during winter, meaning it sits more or less on the equator or little to the south.

My map has a middle-low pressure almost entirely. In the southern hemisphere there is no another landmass. And the areas from Ecuador to the parallel 30 or 35 ° would be tropical climate, wet tropical, warm steppe, desert, some Mediterranean climate at the west of the mountains between 30 ° and 45 ° and in the east would be like Manchuria (Dwa?).

yes it will look like this on the west coast. The east coast is different and I don't think there is a Manchurian climate. The north east is always wet and cannot be Dwa. More like Dfa/Dfb.

The mid-continent area is bisected by a mountain, so in that zone would be mountain climate. And the other areas are relatively close to the coast.

I'm making a plan and I won't include mountain climate. Following the Koppen classification, alpine climate does not exist. It would cover a wide range of possibilities anyway. I will just ingrone that part for the moment.

Thanks for the the pictures of the polar front. But i thought that in summer the polar front can be retired near to the pole. Why it can reached to latitude 30? I thought that in winter the polar front should be very wide and narrower in summer.

Your right, I contradicted my own sources. It goes south during the winter like the ITCZ.

[Facubaci]

Thanks, Deadshade . It Seemed too complicated . I do not want to have a so changeable weather.
I'll do the math you gave to me.

I made ​​a fast sketch with some latitudes and Their equivalents in average temperatures. All at zero meters above sea level . I estimated that in Equator (TE) the average temperature is 25 °. At the poles, I estimated it to 0 ° (TP) (I did not understand if TP is exactly in the pole or it's in the polar front) .
Well , suppose where the drawing shows latitude 45 ° with 1000 meters above sea level, the temperature decrease in 10 °. So, in these high zones the temperature would be 7,5°.

T = (TE - TP) . cos (lat) - 10 . (alt in km) + (TP)
T = (25° - 0°) . cos (45) - 10 . 1 + (0°)
T = 7,67°



And the rainfall would be something like the following.
I have some questions : why there are 0mm/y at latitude 25 ° and the poles? And at 64° and intermediate latitudes, how would be the precipitations?



Let's see if it's more or less well.
I'll read the Whittaker biome diagram and draw the biomes on the map.

Thanks Azelor too!

[Azélor]

0 degree at the poles does not make sense. You should have a look at this : http://commons.wikimedia.org/wiki/Fi...emp_annual.png

Here you have the 2 ITCZ and Polar front. I think I exaggerated, the summer ITCZ go too far north I think.
Attachment 70442

And the resulting climates, a rough version
Attachment 70443

[Facubaci]

Oh wow, Azelor. That simplifies me much work.
I should delete some rivers (like in the desert) and add some of them in more humid areas. By the sketch you did, the colors would be the following:



How would be the rains? Should I distributed it approximately according to your sketch?
Thanks!