First, specifying format in this question

I will be giving temperature ranges that sometimes appear backwards. This is because I am listing average temperature ranges from southern to northern latitudes. My landmasses are mostly located from the equator to the South pole. Therefore, my civilizations, who will mostly live in equatorial and temperate regions, will probably orient South to where more land exists. To the North there is nothing but ocean for thousands of kilometers.

Relevant planetary and solar specifications

I have a planet, Jasmi, with a 31.1 degree axial tilt. It's located in a relatively Mars-like orbit of 1.55 AU around an F7 type star, Xat, with surface temperature 6414 K, mass 1.21 MSol, radius 1.15 RSol, and luminosity 2.01 LSol. My greenhouse effect accounts for 33.08 K of my planet's average temperature.

In a previous version of this question, I had far too low an average planetary temperature to sustain anything like Earth-like plant life. I significantly increased my star's luminosity to compensate for the temperature, changing it from an F0 to an F7 spectral class.

Temperature variations in the tropics

Shagomir's Planet Calculator Pro gives average yearly temperatures in the tropics of 13.85-16.85 degrees C. Obviously my tropical temperatures don't change much throughout the year compared to the rest of my planet; that's what makes them tropics in a latitudinal sense. They do vary much more than Earth's, though. In the Northern summer, my tropics experience temperatures on average of 0.85 - 20.85 degrees C; in the Northern winter, my tropics experience temperatures on average of 25.85 - 4.85 degrees C. This gives an average yearly range of 25 - 16 degrees C.

My poles, as you might expect, are much more extreme.

My South pole has a yearly average of -25.15 - 0.85 degrees C, but in its summer it is 35.85 - 14.85 degrees C on average and in its winter it is -51.15 - -27.15 degrees C on average, giving an average yearly temperature swing of 87 - 42 degrees C.

My North pole is similar but less extreme in Shagomir's model for some reason: its yearly average is -26.15 - 0.85 degrees C, but in its summer it is 10.85 - 31.85 degrees C on average and in its winter it is -51.15 - -26.15 degrees C on average, giving it an average yearly temperature swing of 25 - 27 degrees C.

Given all this, my question:

My year is 640 Earth days long. Therefore each global "season," or sidereal year/4, is 160 Earth days, or 5.26 Earth months. Keeping this in mind, what biomes and climate classifications should I be roughly looking at in my poles and tropics?

  • 1
    $\begingroup$ "Therefore each season is 160 Earth days" why? On Earth we have places with only two seasons (ie dry and rainy), or with six seasons (traditional Polish seasons included "pre-spring" and "pre-winter" — yes, we do have an entire season meaning "winter is coming" ), and there is no rule that forces seasons to be of equal length. $\endgroup$
    – Mołot
    Feb 25, 2018 at 11:33
  • $\begingroup$ @Molot yes, you're totally correct. I'll edit my question to be more clear about what I meant; I was referring less to climate and more just to the temperature variations over the sidereal year/4. $\endgroup$ Feb 25, 2018 at 11:34
  • $\begingroup$ I am not sure the question should be 'WHAT are you asking?' bit instead 'WHY are you asking it?' You appear to have a really good grasp of temperatures. What is left can not be answered unless there is come description of climactic modifiers. For instance, do you have large land masses and oceans? And if so, are these land masses oriented pole-to-pole, like Earth's, or around the equator, or concentrated at the poles? $\endgroup$ Feb 26, 2018 at 2:27

1 Answer 1


Short answer:

Equatorial regions: temperate rainforest

Polar regions: tundra

Long answer:

I assume that if you made such elaborate question, then you expect something more. ;)


  1. I have mixed feelings about this climate on South Pole. I understand axial tilt and so on, but on our warmer planet, on Vostok Station the average annual temperature is -55C.

  2. Such longer seasons make animal migration much more viable strategy than on Earth. Thus big part of fauna should move with seasons.

  3. Longer vegetation season and longer winters makes slightly favours single year plants.

  4. You don't have 4 seasons. Seasons are arbitrary distinction created by local civilisation. Your civilisation lives in tropical region, where what matters is rain season and dry season. Because of higher axial tilt and imbalanced land mass such pattern should also more or less apply to equatorial region.

  5. With such size of star, it should stay in main sequence for 5.7 bln years. Seems OK, until you include that the star luminosity increases even when its in main sequence. Thus a if right now the planet is so cold, then a bilion years earlier it should have been a snow ball. (yes, workable, but it would require some explanation like orbit migration or much higher CO2 content in the past.)


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