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My another question related to already introduced planet Artemis is related to temperature gradient. Whether it will work also in depression deep under sea level and if yes what could be increase of temperature at the sea at bottom of such depression if depth of depression would be 2 km and if it would be 4 km.

Now some details for your consideration, if you would have time to comment (answer) or advice. Artemis has size similar to Earth, it is orbiting its star in average distance like Earth, but with little bit larger eccentricity (causing that differences in seasons in northern hemisphere are larger than differences in southern hemisphere).

Oceans are placed only in northern hemisphere, deserts are almost completely covering southern hemisphere. Two inland seas are placed at southern hemishpere. Smaller sea was discussed yesterday. Concerning larger here is my another question. Larger Southern sea has area of 6344640 sqkm and it is placed between 30° and 50° latitude (on the map in the hyperlink and down under text marked latitudes are 0°, 30° and 50°. One part at latitude and longitudes on map is 1°).

I came with idea, that due to its position so far south, I will place this Southern sea into depression (comparing with northern ocean which is at level 0 m above sea level) with aim to have more mild and more warm climate (than surrounding arid desert placed above 0 m a.s.l.). I calculated temperature gradient at level 0,6-1°C/100 m and for me result was, that if I would like to have tropical climate at sea, than depression should be around 2 km deep.

My question is, will temperature gradient work also in deep large depressions and would temperature increase also in such conditions? Or is it so, that if depression is surrounded by higher placed regions, then temperature gradients would work differently?

Here is my expectation, how weather would work at southern sea. Due to fact that Southern sea in Artemis is in apogee in summer - despite longer days, temperature remain lower during the day in comparison in situation at 50° southern latitude, if planet would have no eccentricity of orbit. In winter in Southern sea is Artemis in perigee. Therefore despite short day, temperature rises very fast in the day, what does not allow sea to be cold, what helps sustain high temperature also in night. Temperatures will be more balanced between seasons - more balanced in comparison with situation, if orbit would not be eccentric. So for instance winter average temperature for July (if they would have moons like Earth) would be 20°C at 48° southern latitude, what is 15° more than in Paris in 48° northern latitude in winter (in January 5°C). In summer (like January in southern hemisphere on Earth) I expect average 25°C in Southern sea. Especially in southeastern part of Southern sea (due to prevailing winds and currents) would be very high precipitation rate and lot of haze in winter due to long nights and warm sea.

So that is all from my description of this Southern Sea at planet Artemis. So if you could write me, how temperature gradient would work (and if) in conditions of my Southern sea at Artemis, I would be glad. And if you would have any remarks concerning weather more generally, I would be also glad.

Just one explanation, why I write here. By coincidence I found this website for discussion concerning wordlbuilding, when I was searching answer about issues concerning water moons. I already published many pictures from Artemis. When I was reading other issues discussed here - I realized, that some of my assumptions were wrong. For instance I thought that at my planet will not be southern polar cap. But according to discussion here in other described similar worlds, solar cap should form also in southern desert hemisphere (so I have to adjust my planet little).

But I did not find topic discussing temperature gradient in depression, so that is why I ask.

Here almost complete map of Southern sea (more detailed in hyperlink above): enter image description here

Approximately 10 % of western corner of sea is missing on the map.

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  • $\begingroup$ Adiabatic lapse rate. 10 °C/km. $\endgroup$
    – AlexP
    Commented Apr 17 at 9:06
  • $\begingroup$ Thank you for this information about adiabatic lapse. That I included into my calculation, just I forget to write that this temperature gradient 0,6°C-1°C is for 100 meters. I will correct it. Unclear for me is, whether temperature gradient will work also in such deep and huge depression and whether in such circumstances will be temperature 2000 m under sea level really higher than it should be at 0 level. Or whether temperature 2000 m under sea level would be like it would be at 0 m asl. Question for me remains, whether such extensive depression would not alter temperature gradient. $\endgroup$ Commented Apr 17 at 17:25
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    $\begingroup$ Oh yes, it works downwards just like it works upwards. It has nothing to with the size of the depression. (The fundamental cause is the variation of air pressure with altitude.) For example, the temperature at the bottom of the dry Mediterranean basin during the Messinian salinity crisis is estimated to have reached 80 °C (176 °F) in summer. $\endgroup$
    – AlexP
    Commented Apr 17 at 17:44
  • $\begingroup$ I just could not imagine example (Dead sea depression is not sufficiently deep). But Messinian crisis is perfect example. Thanks. $\endgroup$ Commented Apr 17 at 18:04

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