Setting Unnamed - World Map in progress.

[Chick]

Eh, I tried. I still don't know how to represent forests.

At the scale of this map, a lot of little tiny green dots should do forests nicely.

[Azélor]

As long as you don't put a large mountain range on the western side, the interior of your main continent should be plenty humid. Arid regions tend to be downwind of mountain ranges, and with large bodies of water in the center, there should be plenty of rain.

Nope, the Arabian peninsula is surrounded by water and it's a desert. So Is all of North Africa and Australia. The rule you mention is an exception around the tropics. Being next to the sea do not guarantee having rain. I think the confusion comes form the fact that most people will understand the air movement in 2 dimensions only. But in reality, it's in 3 dimensions. The descending air over Arabia is dry because it comes form a higher altitude, possibly around 10 km.

The other thing to consider is why does it rain? Having a lot of water in suspension is not enough to create rain. It can stay in the air for a long time. In order to fall, it needs a confrontation with cold air. As the air cools off, it cannot contain all the water. Becoming saturated, it start to rain. The more drastic the temperature gradient, the more violent the reaction is.

Look at you windows: If you live in the north you probably noticed water condensation during winter. That's the same principle as rain.

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So, I believe the climate on this part of your world should be similar to Africa (turned upside down). Tropical rainforests near the equator with an increasingly dry season as we move toward the tropics. Large areas would be deserts around your seas. And the southern portion as a North Africa like climate with the southernmost area similar to Southern and Western Europe.

That being said, most of your seas either fall into a steppe climate or a desert climate. This means a lot of evaporation. I take lake Nasser (an artificial lake on the Nile) in Egypt for comparison: it contains about 132 cube km of water and apparently he lose 10-16 cube km each year due to evaporation. I means that without external water addition, it would lose 10% of his volume each year. This seems like huge numbers but lake Tchad / Chad also as a high evaporation and is a seasonal lake, the lake can almost disappear during the dry summer.

Based on the Sahara, we can estimate that this land would need between 3m and 6m of annual precipitation in order to be considered as humid as the Mediterranean climates. It's half of this if it's under maritime influence of near a large lake.

Most of you lake only have marginal inputs. With sufficient time, about half of the lakes in the middle will disappear and another bunch will almost disappear in the dry season. Of course that depend, if the water flow toward the desert, it's possible to have lakes there. Just like lake Nasser that would be dried quickly without external water sources.

This brings me to question how these seas/lakes appeared in the first place. Was it an ocean that was trapped between 2 landmasses? It seems improbable because it take thousands, millions of years to complete and by that time, the seas would have dried out.

Option 2 would be that a drastic change in the climate occurred in the last centuries perhaps. Or change in the axial tilt. The region used to receive more rain, enough to feed these large lakes with fresh water.

Or maybe it's a combination of the two.

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Lastly, their impact of the climate could be significant. I doubt it would rain much but the relative humidity would be higher than in the central Sahara. The most important difference would be that the temperature would tend to be lower during the day when near the water but also warmer during the nights, compared to areas that are far from the water. This is just because water takes more time to change temperature.

[Azélor]

About you rrivers:

In my last answer, I considered that most lakes had water inputs but mostly no outputs. Having water flowing from these lake mean they will dry out very quickly, unless the climate is different than on Earth. Or unless it's at the same level than the oceans...

Also, it is rare for lakes to have multiple outputs.

[vaiyt]

Thanks for the in-depth explanations! This is a huge learning experience for me, I'm kinda trying to improvise as I go. I can handwave minor incongruencies as the work of magic (this is a fantasy map after all) but I want a realistic framework to build from. =)

So, I believe the climate on this part of your world should be similar to Africa (turned upside down). Tropical rainforests near the equator with an increasingly dry season as we move toward the tropics. Large areas would be deserts around your seas. And the southern portion as a North Africa like climate with the southernmost area similar to Southern and Western Europe.

Almost. In terms of location it's similar to Africa, but the size is more akin to Eurasia. The southern tip is very close to the south pole, while the northern portions are just barely entering the northern temperate zone.

That being said, most of your seas either fall into a steppe climate or a desert climate. This means a lot of evaporation. I take lake Nasser (an artificial lake on the Nile) in Egypt for comparison: it contains about 132 cube km of water and apparently he lose 10-16 cube km each year due to evaporation. I means that without external water addition, it would lose 10% of his volume each year. This seems like huge numbers but lake Tchad / Chad also as a high evaporation and is a seasonal lake, the lake can almost disappear during the dry summer.

Judging by the scale of this map, these lakes are much, much larger than Lake Nasser. My sense of scale is totally wack, but I think the bigger ones dwarf even the Caspian Sea.

Based on the Sahara, we can estimate that this land would need between 3m and 6m of annual precipitation in order to be considered as humid as the Mediterranean climates. It's half of this if it's under maritime influence of near a large lake.

I guessed correctly in this case, then... but that also means I may have to re-evaluate the desert locations in my remaining continents. Would you be able to help me point them out if I gave you a map of the climate zones?

Most of you lake only have marginal inputs. With sufficient time, about half of the lakes in the middle will disappear and another bunch will almost disappear in the dry season. Of course that depend, if the water flow toward the desert, it's possible to have lakes there. Just like lake Nasser that would be dried quickly without external water sources.

This brings me to question how these seas/lakes appeared in the first place. Was it an ocean that was trapped between 2 landmasses? It seems improbable because it take thousands, millions of years to complete and by that time, the seas would have dried out.

Option 2 would be that a drastic change in the climate occurred in the last centuries perhaps. Or change in the axial tilt. The region used to receive more rain, enough to feed these large lakes with fresh water.

Or maybe it's a combination of the two.

Heh, I thought the same thing about lake drainage. I tried to divert the big tropical rivers towards the desert in order to give these lakes sufficient input, but I guess that doesn't explain how they could fill those gigantic bodies of water faster than the sun could dry them up in the first place.

Filling some of those seas up is not out of the question.

Lastly, their impact of the climate could be significant. I doubt it would rain much but the relative humidity would be higher than in the central Sahara. The most important difference would be that the temperature would tend to be lower during the day when near the water but also warmer during the nights, compared to areas that are far from the water. This is just because water takes more time to change temperature.

That's interesting.

About you rrivers:

In my last answer, I considered that most lakes had water inputs but mostly no outputs. Having water flowing from these lake mean they will dry out very quickly, unless the climate is different than on Earth. Or unless it's at the same level than the oceans...

Also, it is rare for lakes to have multiple outputs.

Oh, that's interesting. I actually added the outputs late in the process because I thought it would be nice if they weren't too saline.

[Chick]

But doesn't the Hadley Cell circulation rise at the ITCZ along the equator, making rain forests in equatorial regions?

http://www.srl.caltech.edu/personnel...ere/whemap.gif

I thought the deserts were north and south of the equator, around 20 degrees N and S latitudes where the Hadley circulation sinks, as you described.

http://planetolog.com/maps/map-world...-world-map.jpg

[Azélor]

The top of the middle part of the middle continent is around the equator. Thea part toward the south: that was the part I was talcking about.

I thought the deserts were north and south of the equator, around 20 degrees N and S latitudes where the Hadley circulation sinks, as you described.

Yes, is there a contradiction ? (I can be very distracted sometimes)

[vaiyt]

But doesn't the Hadley Cell circulation rise at the ITCZ along the equator, making rain forests in equatorial regions?

http://www.srl.caltech.edu/personnel...ere/whemap.gif

I thought the deserts were north and south of the equator, around 20 degrees N and S latitudes where the Hadley circulation sinks, as you described.

http://planetolog.com/maps/map-world...-world-map.jpg

The horse latitudes go right through the middle of the lake-filled area and near the north edge of the big eastern/western masses respectively. Everything between them is pretty much equatorial.

[Chick]

The top of the middle part of the middle continent is around the equator. Thea part toward the south: that was the part I was talcking about.

Yes, is there a contradiction ? (I can be very distracted sometimes)

Sorry, thought you were objecting to my statement that the big lakes would be fine and humid if no mountains were placed to block the airflow.

[vaiyt]

The top of the middle part of the middle continent is around the equator. Thea part toward the south: that was the part I was talcking about.

I noticed that a while after I made the post. Your analysis is spot-on.

[Azélor]

Yes the location and the climate should be similar to Africa. Lake Nasser was just an example for water evaporation ratio. Of course, some of your lake are well over 1m sq km and depending on their dept, the evaporation rates can be lower or higher if they are shallow.

I could help with climates but I have a really hard time putting the things at the right place with this map projection. I really like it, I think it look good but it's not practical to work with especially when we move away from the center of the map.

I did a small rough map to explain where the major zones are: red is desert, orange is steppe and green is temperate climate, blue is tropical forests

Attachment 70870