PLANETARY MODEL | PART 1 | BASIC CLIMATE MODEL

CLIMATE MODEL OF YOUR WORLD

Being 4,2Byo, Vol is a main sequence star, bearing 80% the Sun's luminosity and pushing Paart into the mid-HZ.

The planet receives ~72% the light Earth receives from the Sun, what sounds bad 'cuz is a little bit more than what Mars receives and it is pretty cold.

Paart has lots of Titanium, Silicon, Aluminum and Bismuth, combined with Oxygen and Carbon, those can form black rocks of Titanium silicon carbide, Titanium carbide, a black sand made of carbon and titanium, anorthite, a mineral rich in aluminum crystals, and of course Bismite ores.

But that is where enters the magic if physics and chemistry my friend, proportionally, Paart's average temperature should be around 10 degrees Celsius if it had Earth's Atmosphere, but remember the color of the rocks?

They're black, and dark colors absorb light re-irradiating it as heat, at the time, Ozone is not so present and UV and X-ray help warming up the place, with lots of volcanism, even at 4,2Byo Paart has a great balance of greenhouse gas emissions.

Talking about greenhouse effect, the few gases we have proportionally in our atmosphere warm the planet up by ~33 degrees Celsius, without them Earth would be freezing at -18 degrees in average.

Earth at 4,2Byo had a proportion of around ~35% Oxygen to ~65% Nitrogen.

That peak of 35% occurred during the Carboniferous when plant-life over produced Oxygen while consuming the Carbon dioxide content in the atmosphere and volcanic soil.

At the time, Earth average temperature was ~20 degrees Celsius.

Note, our current average temperature is around 15°C.

At the Carboniferous the amount of Carbon dioxide was around  800ppmv, or ~3x times Pre-Industrial Age (~280ppmv), today the average concentration is around ~410ppmv.

Lets assume for a moment that Carbon dioxide is directly related to global temperature, WHICH IS NOT, but we will take that to a future post.

We need ~12,4ppmv per 1°C increase in the global temperature, as taking from -18°C to our global average 15°C.

And then ~80ppmv per ~1,5°C increase to reach the Carboniferous 20°C average at 800ppmv.

(reality shows roughly ~100ppmv per ~1°C).

This change in scale is needed probably due to the atmospheric pressure, when the air can't get any denser in order to increase it's heat transfer capacity, unless you have some serious amount of CO² like Venus.

Anyways, we can consider any value between 400 and 1000 as "Valid" within 10°C margin.

Using this model I poorly made, we can tell a certain range of temperature increase for certain amounts of Carbon dioxide in a Earth-like atmosphere pressure/basic composition.

I don't want to flee much from Earthly standards, remember when I said stromatolites are dead due continental rise? We can say that by this time the Great Oxygenation Event didn't happen in Paart, life went on after the stromatolites died and life on Paart didn't needed to breath oxygen at all, they can use all that available carbon dioxide to obtain the oxygen gas and carbon needed for their metabolism to work nicely, that's why I choose some kind of amphibian-like creature to start, not only because it is the age of the first tetrapods hexapods, but because they can breathe through their skin, releasing some methane and carbonic gas as output of their functions.

Carbon absorbed through respiratory system can easily make up the pearl-looking bismuth oxides, the dark-blue copper compounds in shells of marine animals, scales of armored fishes, teeth and claws of other animals, like some deep sea worms actually have.

In this case, Paart's atmospheric carbon dioxide content may be around 855ppmv.

For now we stick with the average temperatures ranging from 10° to 30°C.

If you plan an earthly biology going around, keep it below 1000ppmv (0,1% atmosphere).

UPDATE

A planet's average temperature relative to Earth is given by:

Where T~Earth = 1 = 255K, L is the luminosity of your star to the power of 1/4 and D is the distance of your planet to the star in AU to the power of 1/2.

In this case, Paart is T~0,899, or about 228K, or -45ºC, what makes sense of a planet without any atmosphere, as said Earth is expected to be at -18ºC without an atmosphere.

But, the formula doesn't take into account, the Greenhouse effect, the more far away from 288K you get, the less reliable it will be, so comes Indiana's Planetary Temperature Calculator.

Using Indiana, the result is around 30°C, pretty close of what we previously established already, hence I would recommend calculating your Greenhouse effect into the amount of carbon you have, at 855ppmv, I consider Paart as having ~2,08x the greenhouse effect than on Earth, hence -15ºC + 2(33ºC) = 51ºC, but Paart only receives as much as 64% sunlight as Earth, then 51ºC*0,64 = 32,64ºC, which is also into the range we defined earlier.

Good modeling, bye :)

- M.O. Valent, 13/05/2019
- M.O. Valent, Updated in 09/09/2019