Iryth : My second project, a world this time!

[BookOwl]

Wow this is like way cool so far! Love all the technicalities you figuring

[Brennall]

Thanks for the kind comments guys

In a little side note before the climate zone work, I had to work out the physical properties of my world today. Specifically looking at gravity and density, there is a wonderful resource here Planet Designer which can help you find Gravity, geosynch orbit and Roche limit. I was aware I had done some guesswork regarding planetary density to fake the reduced gravity of my world, but I got the urge to understand more last night and see whether it was possible!

Here is a readout for Mars (the nearest in terms of size to my planet)

Day Length: 24.6 hours (2.5 seems to be the lower limit for asteroids, 10 to 24 is typical, more for tidally locked bodies)
Mass: 0.107 relative to Earths
Density: 3.93 g/cm3

Minimum Density for terrestrial planet of this mass (Pure Water) = 1.8 g/cm3
Typical Density for terrestrial planet of this mass (Earth like) = 4.9 g/cm3
Maximum Density for terrestrial planet of this mass (Pure Iron) = 10.3 g/cm3
Diameter = 6780 km
Surface Area = 144.3 million square km
Roche Limit = 900 km (nearest possible natural satelite)
Surface Gravity = 0.38 Gs
To Orbit Velocity = 3.55 km per second
Thrust to orbit time at 3G = 2.3 minutes
Escape Velocity = 5 km per second

Geosynchronous orbital distance = 17020 km, or 10630 miles (from surface of planet)
Geosynchronous orbital velocity = 1.45 km/s , or 0.9 miles per second

As I could not increase the diameter without affecting my mapping, I was left with changing the mass and density (as I had suspected during the guessing done earlier). I noted the Max Density was 10.3 g/cm3 so had some limits to play with.

After some fiddling around with Mass and density I settled for a lower surface gravity (0.83 Gs) than Earth with a 24hr Day length.

Here is the final result in the same format.

Day Length: 24 hours (2.5 seems to be the lower limit for asteroids, 10 to 24 is typical, more for tidally locked bodies)
Mass: 0.2448 relative to Earths
Density: 9 g/cm3

Minimum Density for terrestrial planet of this mass (Pure Water) = 1.8 g/cm3
Typical Density for terrestrial planet of this mass (Earth like) = 4.9 g/cm3
Maximum Density for terrestrial planet of this mass (Pure Iron) = 10.3 g/cm3
Diameter = 6780 km
Surface Area = 144.3 million square km
Roche Limit = 900 km (nearest possible natural satelite)
Surface Gravity = 0.87 Gs
To Orbit Velocity = 5.38 km per second
Thrust to orbit time at 3G = 4.2 minutes
Escape Velocity = 7.6 km per second

Geosynchronous orbital distance = 23060 km, or 14410 miles (from surface of planet)
Geosynchronous orbital velocity = 1.92 km/s , or 1.2 miles per second

As you can see, a denser planet, but with a believable (kind of) gravity and planetary characteristics. Now I can put that to rest and return to my mapping

Comments and Critique welcome ...

[s0meguy]

My big beef with Fractal Terrains is that it almost always generates the mountauin ranges in the middle of continents, and the continent shapes usually don't look very natural, ie as a result of tectonic plate movements. If not for that, i think this style can produce good quality "maps", quotation marks because they look more like satellite pictures.

[Brennall]

That is why I spent some considerable time at the beginning adding land mass around the "mountain ranges" to make sure they were not "Equal" or in the middle.

Quick camera shot of my WIP on the desk ..



As you can it is getting windy in my office

wip.jpg

[Brennall]

The two AD&D books dealing specifically with "The wilderness" were mentioned a few posts above. The World Builders Guidebook (WBG) and the Wilderness Survival Guide (WSG), both of then categorise terrain with similar but different systems. However they both use climate "banding" to break up the globe, specifically Arctic, Sub-Arctic, Temperate, Sub-Tropical and Tropical. The problem is they disagree about the size of these areas. The WBG uses an Icosahedron to represent spherical worlds with a hexagonal grid, each zone getting a certain number of hexes: -

Arctic - 2.5hexes
Sub-Arctic - 3 Hexes
Temperate - 2.5 Hexes
Sub-Tropical - 2.5 Hexes
Tropical - 3 hexes (To the equator about 1.5hexes)

A Grand total of 12 Hexes from pole to Equator. Each hex being 7.5 degrees latitude

So that means: -

Arctic 18.75 Degrees = 71.25 degrees - 90 degrees
Sub-Arctic - 22.5 Degrees = 48.75 - 71.25 degrees
Temperate - 18.75 Degrees = 30 - 48.75 degrees
Sub-Tropical - 18.75 Degrees = 11.25 - 30 degrees
Tropical - 22.5 Degrees (11.25 Degrees to the Equator) = 0 - 11.25 degrees

The WSG gives us real degrees to work with starting on Pg. 107

Arctic 24 Degrees = 66 degrees - 90 degrees
Sub-Arctic - 16 Degrees = 50 - 66 degrees
Temperate - 20 Degrees = 30 - 50 degrees
Sub-Tropical - 15 Degrees = 15 - 30 degrees
Tropical - 30 Degrees (15 Degrees to the Equator) = 0 - 15 degrees

As you can see the numbers disagree, but are broadly similar (as one would hope). Obviously real numbers are much nicer to play with than portions of hex and inherently more trustworthy because of that alone.

Now Wikipedia suggest the following: -

Arctic 20 Degrees = 70 degrees - 90 degrees
Sub-Arctic - 20 Degrees = 50 - 70 degrees
Temperate - 43 Degrees = 23.5 - 66.5 degrees
Sub-Tropical - 16.5 Degrees = 23.5 - 40 degrees
Tropical - 47 Degrees (23.5 Degrees to the Equator) = 0 - 23.5 degrees

As you can see, Wikipedia overlaps the Temperate zones to cover both Sub-Tropical and Sub-Arctic zones. I belive this is current thinking on the subject (sub-arctic and sub-tropic are in decline). Given all the obvious overlaps between zones (which I believe is quite accurate as climate conditions don't just stop on a latitude) and the fact that the WSG zones fit within the scope of the wikipedia ones, I will got with the WSG climate zones.

Here is how it looks ...



As you can see from the WIP above, I am working on Winds for next time!

Comments and Critique welcome ..

climatezones.jpg

[BookOwl]

Ooh, where are you getting the info about winds and currents stuff? I'd love to look at it.

This is looking really awesome so far!!

[Lyandra]

It's great to see this project develop. Very ambitious.

[Brennall]

I am still experimenting with the Winds or Iryth. I firstly produced a Non-season specific wind map which laid out most of the directions and areas on the map such as the equatorial doldrums etc.



Once I had got the basic wind direction and normal patterns, I adjusted for Seasonal variation (the movement of the solar equator due to axial tilt).

Here is the "Northern Hemisphere Winter / Southern Hemisphere Summer" ...



I think I have followed all the basic guidelines about the locations of the High and low pressure systems. If anyone can see anything wrong please don't hesitate to comment as I want to get this right before proceeding.

In addition here is the "Southern Hemisphere Winter / Northern Hemisphere Summer" ...



So if anyone has anything to add before I generate the wind flows between high and low pressure please comment!

Thanks!

@ Bookowl : The climate cookbook was a great help .. The Climate Cookbook

@ Lyandra : I hope it is interesting .. it is consuming massive amounts of time

irythbasicwindmap.jpgirythnorthernwinter.jpgirythnorthernsummer.jpg

[Diamond]

A lot of thought and work put into this. I like what I'm seeing.

[Sathurn]

I like it.