[WIP]: A new RPG World

[SteffenBrand]

Wow, I'm really impressed by your response to this, thank you! =)

Pressure Zones and winds are my achilles' heel, I really have difficulties wrapping my head around the concept. I understood it this way:

1. There are global winds, the atmospheric circulation you mentioned. This doesn't change. You correctly assumed earth-like circumstances (rotation, planet mass, etc.).

2. There are winds that change direction. This can't be predicted more than theoretical 30 days in advance, making this highly irregular. But some of them are recurring phenomenons like monsoons, uplifting winds at mountains, etc.

3. Coriolis force describes the winds direction, changing in the northern / southern hemisphere. I need to do this again I guess in my map.

4. A question to your post: Are you sure about the wind direction between 30° and 60°? It seems to me you are the expert on this, however it really feels off. The cells you described on the right are pointing in another direction. Is this, because of the pressure zone there?

5. Thanks for the biomes you drew in. Doing some fixes there. This overall feels like a neverending process, there will come a point where I need to just stop and go on with the work on this... =)

Cheers, have some Rep!
Steffen

[Deadshade]

I wouldn't call what I drew "winds" but atmospheric circulation.
The difference being that winds are what happens at a given time at a given point e.g locally while AC is the yearly average of what happens over a zone.
That's why winds are more or less random and may change all the time while AC is neither random nor changes all the time. Well it is and it does but at much, much bigger time scales - decades, centuries and more.

That's why if you do a map and want to place the biomes correctly, it doesn't matter if you get all the micro climates (monsoons included) right. You only need to get the fundamental (invariant) climatic features e.g temperatures and humidities right. It is onlyif you have time and interest that you can then fine tune the climate and the corresponding biomes at regional scales.
And these fundamental features are all resumed in the schematic on the right edge of the map I joined.

To 4.
Yes I am
The cells on the right edge are a vertical section of the atmosphere. The green line is the ground and the blue (cold) and red (hot) lines show how the atmosphere circulates in these cells. You must imagine a cell like a cylinder with its axis running all around the planet and parallel to the latitude circles.
So back to what made you Wonder.
At 30° the high altitude cold and dry air of the Hadley cell is going down what creates there incidentally high pressure zones.
Once it is on ground, it must close the loop (mass conservation) and starts to move back to the equator.

The neighbouring Ferrel cell is doing the same - high altitude cold dry air is also going down at 30°.
Once it is on ground, it must also close the loop and starts moving northwards (towards the 60°) where it will go up.
But as I said in the previous post, the Coriolis force in N hemisphere deviates to east what moves northwards (and to west what moves southwards).
Also its intensity increases when the latitude increases.
So as the air of the Ferrel cell travels on ground northwards, it is deviated more and more strongly to east and the result are the arrows I drew.

Basically the temperate humid zones I drew are like Ireland.
The dominating circulation comes from the west (Coriolis etc) and to the west is an ocean. That's why this air is saturated and will release the rain at any occasion it gets. What is quite often

Just incidentally - you don't need to take the polar cells seriously. They are the smallest and weakest of the 3 so they are not very important. The only thing Worth noting is that you have a high pressure on pole, everything is cold and horribly dry (lowest humidity on a planet are not deserts but poles), and the circulation is basically just a ring flowing clockwards (N pole) around the pole's High.

[Azélor]

There is one thing that was overlooked with the AC: it moves following the seasons. The equatorial low pressure can above the tropic during the northern summer.

[Deadshade]

There is one thing that was overlooked with the AC: it moves following the seasons. The equatorial low pressure can above the tropic during the northern summer.

Well not really overlooked but neglected. The ITCZ oscillates with seasons but only if the rotation axis is not orthogonal to the orbital plane (e.g the Hadley cell moves N in northern summer and S in northern winter).
The exact movement of the ITCZ is very complex and depends completely on the distribution of oceans and continents so that on Earth it hardly seasonaly moves on some places (America) while moving quite a distance on others (Eastern Asia)
As I assume in this simplified schema that the rotation axis is orthogonal to orbital plane, there are no such oscillations.

[Azélor]

Steffen, Is the planet tilted like Earth ?

I understand it gets more complicated but it does have a large impact on the climate in Asia, as you mentioned. If there is no tilt at all, the temperature at a given place would be similar to the temperature on Earth during the equinoxes. Meaning that I would almost live in the tundra

[SteffenBrand]

@Azelor: Yes, it is. I thought about it but it offers much more diversity if it is tilted, even thou as you mentioned this makes it a bit more complicated. And hey, who wouldn't like Québec as it is?

@Deadshade: Thanks for the clarification, you've been - once again - a huge help! I'll look for more infos about this and try to get the concept completely. Being able to recreate this is usually the point when you got it =)

[Deadshade]

Glad to help. Especially because your map is really nice - I can't wait to see the mountains.
So now when you decided that the axis is tilted (Earthlike ?) you get an oscillating ITCZ what means that the cells seasonally move N (in N summer) and S (in N winter).
I would not recommend to go in this effect deeper - unless you have at home a supercomputer and a full atmosphere-ocean coupled circulation model

Actually it is not important if what you want to get (approximately) right are the biomes. The biomes are distributed according to climatic averages (e.g decades and more).
And a time average of an oscillating function is 0. That means that the time averaged position of the ITCZ is the equator and the time averaged circulation looks like what I draw.
Of course when the equator runs on the continent the amplitude is bigger than on ocean but luckily your map has no large land masses on equator.

The only seasonal feature that you could look up because it impacts biomes are the monsoons. And if you have the time of course.
F.ex here : http://isites.harvard.edu/fs/docs/ic...lo_Monsoon.pdf. I like this paper much because they start with a very simple planet model to show what the fundamental dynamics of monsoons are.

[SteffenBrand]

Geez, Deadshade, thanks again, this will be my evening lecture
I guess all I can say now is I'd rep you, but since I can't at the moment I'll invite you for a beer if I ever meet you in person.

I'm on the mountains btw, testing out stuff. Since I'm writing on the core book simultaneously I can't say when I'm able to show the next step. But I'll stay on it, the planning and brainstorming along with building the rule set for this RPG took years. =)

[Deadshade]

I guess all I can say now is I'd rep you, but since I can't at the moment I'll invite you for a beer if I ever meet you in person.

=)

Haha danke. Eine Pilsner Urquel lehne Ich nie ab Jedoch bin Ich nicht sicher wann/ob Ich Hamburg nächst besuche ( insbesondere da Ich jetzt wegen einer schweren Ischiaskrise an der Wirbelsäule operiert werden musste).

[SteffenBrand]

Irgs, klingt furchtbar. :/ Gute Besserung in jedem Fall, sag einfach bescheid wenn du mal da bist