Gurps Space. Axial tilt and Climate

[ericthered]

Originally Posted by pro100kostya

Yes. I should consider all this. But I think air and oceanic currents make way more impact on heat transportation than thermal inertia and the latter is negligible.

I think thermal inertia drives the air and oceanic currents.



Observe that two months on each side of the summer solstice each receive the same amount of sun. The 20th of april and the 20th of august have the same amount of sun, but radically different weather. This is because in april its been cold all winter and spring and the heat goes into warming the place up, while in august things have already been hot for a while. The greatest amount of sun is received in late June, but the average temperature doesn't start dipping until the amount of sun starts approaching average again.

[pro100kostya]

Originally Posted by ericthered

I think thermal inertia drives the air and oceanic currents.



Observe that two months on each side of the summer solstice each receive the same amount of sun. The 20th of april and the 20th of august have the same amount of sun, but radically different weather. This is because in april its been cold all winter and spring and the heat goes into warming the place up, while in august things have already been hot for a while. The greatest amount of sun is received in late June, but the average temperature doesn't start dipping until the amount of sun starts approaching average again.

Oh, this is thermal inertia!
I thought of completely another thing.

[Frost]

Originally Posted by pro100kostya

So.. I've built a world. I've got axial tilt and Average surface temperature. But how to get temperatures at different latitudes and time of year depending on axial tilt?

I know there are no such rules. I'd like to know what you guys think. Maybe some of you did such computations.

I know I am coming in a bit late here but there certainly were bare bones rules for this in 3e. Possibly as a side bar in Space.[Edit] Actually Traveller First In[/Edit]

Off the top of my head it assumed that the surface temperature in the stats determined the climate type at 30° with temperatures at the equator being two climate levels higher and the poles being four levels lower. More detailed changes with latitude and variations with terrain were worked out using a planetary map.

Temperatures at higher latitudes were assumed to be one level higher than this in summer and one lever lower than this in winter for every 15° (I think) [Edit] 18° and 12°[/Edit] of axial tilt.

[pro100kostya]

Originally Posted by Frost

I know I am coming in a bit late here but there certainly were bare bones rules for this in 3e. Possibly as a side bar in Space.[Edit] Actually Traveller First In[/Edit]

Off the top of my head it assumed that the surface temperature in the stats determined the climate type at 30° with temperatures at the equator being two climate levels higher and the poles being four levels lower. More detailed changes with latitude and variations with terrain were worked out using a planetary map.

Temperatures at higher latitudes were assumed to be one level higher than this in summer and one lever lower than this in winter for every 15° (I think) [Edit] 18° and 12°[/Edit] of axial tilt.

Wow, I should read it. Thanks.

[thrash]

Possibly of interest, from the arXiv:

The Key Factors Controlling the Seasonality of Planetary Climate

"Several different factors influence the seasonal cycle of a planet. This study uses a general circulation model and an energy balance model (EBM) to assess the parameters that govern the seasonal cycle. We define two metrics to describe the seasonal cycle, ϕs, the latitudinal shift of the maximum temperature, and ΔT, the maximum seasonal temperature variation amplitude. We show that alongside the expected dependence on the obliquity and orbital period, where seasonality generally strengthens with an increase in these parameters, the seasonality depends in a nontrivial way on the rotation rate. While the seasonal amplitude decreases as the rotation rate slows down, the latitudinal shift, ϕs, shifts poleward. A similar result occurs in a diffusive EBM with increasing diffusivity. These results suggest that the influence of the rotation rate on the seasonal cycle stems from the effect of the rotation rate on the atmospheric heat transport."

[hal]

World Tamer's Handbook from GDW has formulas for what you want, including seasonal effects, night/day effects, etc

You could easily adapt it for use with GURPS SPACE. You can either pick it up from Far Future Enterprises and buy disks of entire Traveller products by line, or buy the one PDF by itself.