As some of you may know, I don't like to use lots of math when creating things for Traveller. I will, and I have, and I've written code to do it for me, but ideally I prefer to know what I'm doing. And often the complexity of math hides what's going on, resulting in a surprise output. I dislike those kinds of surprises.
But when it comes to world building, there seems to be no escape from math. Solar systems and worlds are both complex systems.
Here's my first stab at making it simple: a set of tables which map to average equatorial temperature and the hadley latitude.
1. World Orbit. If the world is one orbital track outward or inward from the Habitable Zone, then the Temperature Index is -1 or +1, accordingly. Similarly, the index is -2 or +2 if it's two orbital tracks outward or inward.
2. World Density. Low density worlds get -1 to both the Temperature Index and Hadley Index, while high density worlds get +1 to both. Density itself is generated with a flux roll, not included here.
3. Day Length.
A day length of less than 1 hour gets +2 to the Hadley Index.
A day of 1 to 11 hours gets -0.25 to the nighttime temperature index, and +1 to the Hadley Index.
A 12 to 24 hour day gets -0.5 to the nighttime temperature index.
25+ hours gets -1 to the nighttime temp index and -1 to the Hadley Index.
Day length itself is generated with a flux roll, not included here.
4. Eccentricity.
1 to 5% gets +0.5 to the Seasonal Temp Index and +1 to the Hadley Index.
6 to 10% gets +1 to Seasonal Temp and +2 to Hadley.
10 to 20% gets +1.5 to Seasonal Temp and +3 to Hadley.
Over 20% gets +2 to Seasonal Temp and +4 to Hadley.
Eccentricity is generated with a flux roll, not included here.
5. Axial Tilt. This affects the Hadley Index only, as follows.
0 to 2 degrees, -3.
3 to 10 degrees, -2.
10 to 20 degrees, -1.
30 to 40 degrees, +1.
40 to 50 degrees, +2.
50 to 60 degrees, +3.
Over 60 degrees, +4.
Tilt is generated with a flux roll, not included here.
6. Trade Codes. This is still in process, but suffice to say that trade codes can have a strongly moderating effect on temperature, or alternately may help create highly hostile environments.
7. Albedo. Albedo strongly affects Temperature and Hadley Indices in identical ways. First, however, I typically restrict albedo between [0.1 and 0.9].
Albedo 0.1 = +2 to both.
Albedo 0.2 = +1 to both.
Albedo 0.4 = -1 to both.
Albedo 0.5 = -2 to both.
Albedo 0.6 = -3 to both.
Albedo 0.7 = -4 to both.
Albedo 0.8 = -5 to both.
Albedo 0.9 = -6 to both.
Albedo is generated with a flux roll, not included here.
8. Greenhouse Effect. This affects the Temperature Index only:
0.0 = -6
0.1 to 0.2 = -5
0.2 to 0.4 = -4
0.4 to 0.6 = -3
0.6 to 0.8 = -2
0.8 to 1.0 = -1
1.0 to 1.2 = +0
1.2 to 1.4 = +1
1.4 to 1.6 = +2
1.6 to 1.8 = +3
1.8 to 2.0 = +4
2 to 3 = +5
3 to 4 = +6
Higher = +7
GE is generated with a flux roll, not included here.
9. Continents. The sizes and placement of continents (again, generated by a flux roll) may bump up the Hadley Index by 1, maybe 2, while the presence of High Volcanism may push down the Temperature Index by 1.
10. Variance (a flux roll). The Temperature Index might have a final push, or not. about half the time it will go up or down by 0.5, and about 5% of the time it will go up or down by 1, otherwise it stays as-is.
The result of all this are some indices centered around (1) a Temperature Index, and (2) a Hadley Index. These two indices are lookups on an "Average Tropical Temperature" table, and a "Hadley Latitude" table.
The Temperature table runs from an index of -12 to +17, and represents temperatures ranging from Absolute Zero (which should not be possible in most cases... maybe in no cases) to 1725 C (where titanium melts). An index of +0 is ideal Temperate, representing 25C plus or minus. -1 is 0 C, and +1 is 50 C, and temperatures go from there by 25s, with some acceleration around +325 C.
The Hadley table runs from -5 to +7, and maps to Hadley Latitude - a measurement in degrees on when the next temperature band begins, starting from the equator. For example, a Hadley Index of +0 maps to a Hadley Latitude of 20 degrees, indicating that temperatures decrease roughly every 20 degrees from the equator. So there are temperature bands at 0 degrees, 20 degrees, 40 degrees, 60 degrees, and 80 degrees (90 degrees is at the poles). On the other hand, a Hadley Index of +3 maps to a Hadley Latitude of 45 degrees. That means there would only be TWO temperature zones between the equator and a pole -0 degrees, and 45 degrees. A Higher Hadley Index also implies stronger winds and more devastating storm activity.
But when it comes to world building, there seems to be no escape from math. Solar systems and worlds are both complex systems.
Here's my first stab at making it simple: a set of tables which map to average equatorial temperature and the hadley latitude.
1. World Orbit. If the world is one orbital track outward or inward from the Habitable Zone, then the Temperature Index is -1 or +1, accordingly. Similarly, the index is -2 or +2 if it's two orbital tracks outward or inward.
2. World Density. Low density worlds get -1 to both the Temperature Index and Hadley Index, while high density worlds get +1 to both. Density itself is generated with a flux roll, not included here.
3. Day Length.
A day length of less than 1 hour gets +2 to the Hadley Index.
A day of 1 to 11 hours gets -0.25 to the nighttime temperature index, and +1 to the Hadley Index.
A 12 to 24 hour day gets -0.5 to the nighttime temperature index.
25+ hours gets -1 to the nighttime temp index and -1 to the Hadley Index.
Day length itself is generated with a flux roll, not included here.
4. Eccentricity.
1 to 5% gets +0.5 to the Seasonal Temp Index and +1 to the Hadley Index.
6 to 10% gets +1 to Seasonal Temp and +2 to Hadley.
10 to 20% gets +1.5 to Seasonal Temp and +3 to Hadley.
Over 20% gets +2 to Seasonal Temp and +4 to Hadley.
Eccentricity is generated with a flux roll, not included here.
5. Axial Tilt. This affects the Hadley Index only, as follows.
0 to 2 degrees, -3.
3 to 10 degrees, -2.
10 to 20 degrees, -1.
30 to 40 degrees, +1.
40 to 50 degrees, +2.
50 to 60 degrees, +3.
Over 60 degrees, +4.
Tilt is generated with a flux roll, not included here.
6. Trade Codes. This is still in process, but suffice to say that trade codes can have a strongly moderating effect on temperature, or alternately may help create highly hostile environments.
7. Albedo. Albedo strongly affects Temperature and Hadley Indices in identical ways. First, however, I typically restrict albedo between [0.1 and 0.9].
Albedo 0.1 = +2 to both.
Albedo 0.2 = +1 to both.
Albedo 0.4 = -1 to both.
Albedo 0.5 = -2 to both.
Albedo 0.6 = -3 to both.
Albedo 0.7 = -4 to both.
Albedo 0.8 = -5 to both.
Albedo 0.9 = -6 to both.
Albedo is generated with a flux roll, not included here.
8. Greenhouse Effect. This affects the Temperature Index only:
0.0 = -6
0.1 to 0.2 = -5
0.2 to 0.4 = -4
0.4 to 0.6 = -3
0.6 to 0.8 = -2
0.8 to 1.0 = -1
1.0 to 1.2 = +0
1.2 to 1.4 = +1
1.4 to 1.6 = +2
1.6 to 1.8 = +3
1.8 to 2.0 = +4
2 to 3 = +5
3 to 4 = +6
Higher = +7
GE is generated with a flux roll, not included here.
9. Continents. The sizes and placement of continents (again, generated by a flux roll) may bump up the Hadley Index by 1, maybe 2, while the presence of High Volcanism may push down the Temperature Index by 1.
10. Variance (a flux roll). The Temperature Index might have a final push, or not. about half the time it will go up or down by 0.5, and about 5% of the time it will go up or down by 1, otherwise it stays as-is.
The result of all this are some indices centered around (1) a Temperature Index, and (2) a Hadley Index. These two indices are lookups on an "Average Tropical Temperature" table, and a "Hadley Latitude" table.
The Temperature table runs from an index of -12 to +17, and represents temperatures ranging from Absolute Zero (which should not be possible in most cases... maybe in no cases) to 1725 C (where titanium melts). An index of +0 is ideal Temperate, representing 25C plus or minus. -1 is 0 C, and +1 is 50 C, and temperatures go from there by 25s, with some acceleration around +325 C.
The Hadley table runs from -5 to +7, and maps to Hadley Latitude - a measurement in degrees on when the next temperature band begins, starting from the equator. For example, a Hadley Index of +0 maps to a Hadley Latitude of 20 degrees, indicating that temperatures decrease roughly every 20 degrees from the equator. So there are temperature bands at 0 degrees, 20 degrees, 40 degrees, 60 degrees, and 80 degrees (90 degrees is at the poles). On the other hand, a Hadley Index of +3 maps to a Hadley Latitude of 45 degrees. That means there would only be TWO temperature zones between the equator and a pole -0 degrees, and 45 degrees. A Higher Hadley Index also implies stronger winds and more devastating storm activity.
