# Predicting Temperature Variation on Planets with High Eccentricity or Long Diurnal Periods

Whew! That title was a mouth-full, but accurate I hope. What I'm trying to figure out is a model for calculating the approximate temperature variation for a generally earth-like planet (similar atmosphere, large oceans, etc.) under two concurrent conditions:

1. High Eccentricity: 0.1, 0.2, 0.3 etc.
2. Long Diurnal Periods: 72 hours - 960 hours (the later could reflect a planet in a 2:1 orbital resonance around a M Star).

(Assume Obliquity = 0 so as to simplify things)

I know conditions like the mass of the atmosphere and the size of the oceans play a key role in the retention and redistribution of heat. However I've been unable to locate any research papers or explicit models that would help. It's relatively straightforward to calculate real temperature (effective temperature modified for greenhouse effect) for both periapsis and apoapsis, however I've had no luck in finding resources for figuring out how much of this temperature variation would be mitigated by retention and redistribution. Same with long nights and long days.

If a specific example would help, let's consider a planet with the following characteristics:

• 30-day orbit
• 15-day (720 hour) rotation (2:1 orbital resonance)
• 30-day solar day (sunrise to sunrise)
• 0 obliquity
• 0.25 eccentricity
• Earth-like in other respects

Calculations or even simply links to applicable research papers would be immensely helpful. Thanks!

• You have cross-posted this, with the other almost identical question on Worldbuilding SE. This is against the rules AFAIK. Jan 10, 2018 at 11:12
• @StephenG It is? Can you please link me to the relevant rule(s)? I was under the impression each Stack Exchange is its own little independent world (I'm new to Stack Exchange). Jan 10, 2018 at 18:11
• Rules for SE tend to be developed and defined on the Meta sites and the most relevant statement I could find on this was this Q&A on the StackExchange Meta. This isn't written in stone - SE moderators are generally reasonable about things - but cross posting is discouraged because it dilutes the answers and spreads them out. Astronomy SE ideally deals with facts and known theory, whereas you are really designing a fictitious planet. Jan 10, 2018 at 19:50
• @StephenG How might I modify my question to make it conform more to the purpose of the Astronomy exchange? I'm really looking for good theory and models. I've provided a specific example b/c I think it would be helpful, but what I really want to figure out it the general model. Jan 10, 2018 at 23:14
• There is an Earth Sciences SE which does climate modeling, but I suspect your question is far to general for them. You'd be best to search their answers for climate modeling concepts. Honestly, Worldbuilding, which has science and hard-science tags for questions, strikes me as the most appropriate. I've seen plenty of users from Physics SE and Astronomy SE on Worldbuilding SE as well. Jan 10, 2018 at 23:32