Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Polar areas would be much much colder than they are now. They would not see the sun at all for much of the year. If the south pole was a mile below sea level I think it would regularly see temperatures of at least -200F...if not lower. Just look at the moon's craters that don't see sun.
I was considering creating a new thread, but I think this post belongs here; not to mention it would bump this fascinating topic .
I was wondering about a possible scenario with these extreme low altitude climates. What if there was a planet with a rift valley like a post on the last page with large areas of these low altitude places, combined with extreme high altitude places next to the low areas? Assuming an otherwise Earth-like atmosphere, these may cause extreme chinook winds for instance, and extreme rain shadow effects. With such altitude extremes, leeward of the mountain ranges may be a extremely hot, dry, and windy deserts, and on the windward side there may be more typical temperatures (cooler at altitude) with extreme amounts of moisture due to orographic lift. The extremes of the Western U.S. would look tame in comparison.
Would the extremes in altitude also drive stronger storm systems? And what would the differences in weather be like with extremes unlike anything seen on Earth, like a mountain range at 10 000 meters above sea level with a valley 10 000 meters below sea level? Assuming of course the ocean arrangements are such that moisture is extracted and all the low altitude areas don't fill in with water.
And another concept to ponder - on an alien planet with thinner air than the Earth, say more Mars-like, extreme variations in altitude like above could lead to interesting phenomena. For instance, if the air is marginal for habitability at "sea level", 5000 or 10 000 meters down the air may be thick enough for habitability, whereas other altitudes would be too thin. This could lead to a place with life and plant cover in rift valleys with lifeless Mars-like deserts at higher altitudes, and an ice cap state at intermediate altitudes. This would also lead to an interesting landscape as seen from space, with rifts of green alternating with oceans and desert mountain ranges.
These questions do veer into astronomical speculation, but it is an interesting climatic question connected to the original post of this topic.
Definitely worth thinking about! Actually, it sounds very C.S. Lewis - Out Of The Silent Planet.
I've thought of the opposite, too - a heavier, super-tropical earth with oceans around 40-50C and life clustered around the ( I imagine extremely rainy ) high altitude locations, the lowlands a steamy desert.
Mars reminds me of Olympis Mons and the intriguing idea of a mountain that extends above the atmosphere. I'm imagining a world with a mountain range so high the atmosphere must move around it, and what kind of climates that might generate.
The wind question is a good one. Antarctica generates huge Katabatic winds due to its height and temperature difference... I'm imagining given any deep basin's pressure and temperature difference it would have a similar dynamic.
I've thought of the opposite, too - a heavier, super-tropical earth with oceans around 40-50C and life clustered around the ( I imagine extremely rainy ) high altitude locations, the lowlands a steamy desert.
Have your oceans too hot and you'll have a runaway greenhouse effect.
Not sure what the threshold is, but a mean global ocean temperature of 40°C-50°C might be enough.
Have your oceans too hot and you'll have a runaway greenhouse effect.
Not sure what the threshold is, but a mean global ocean temperature of 40°C-50°C might be enough.
That's a good question, but from studies of how "ocean planets" would behave in hotter orbits, it seems like such temperatures would create a thick, steamy atmosphere, but not a runaway greenhouse effect. The studies examined "supercritical" ocean planets with temperatures near the boiling point. Notwithstanding the case of Venus and Gliese 581 c, terrestrial planets which naturally would work differently, I still think 40-50C would be pretty safe as a mean ocean temperature, although not necessarily safe for any humans living near it .
Quote:
Originally Posted by CairoCanadian
Definitely worth thinking about! Actually, it sounds very C.S. Lewis - Out Of The Silent Planet.
I've thought of the opposite, too - a heavier, super-tropical earth with oceans around 40-50C and life clustered around the ( I imagine extremely rainy ) high altitude locations, the lowlands a steamy desert.
Interesting that I (a cold weather fan) would think of a marginally habitable cold, thin-air planet, and you (a warm weather fan) would think of a marginally habitable hot, thick-air planet. It's likely that your low-altitude regions would be deserts, and likely would be hotter than the oceans due to the heating of land versus water. So there would be on your hypothetical planet super-humid deserts at perhaps 60C in the lowlands. If it's 50 or 60 C and super-humid, then it would likely kill a human on the spot, considering that the dew points (which would likely be well above 37C) would be enough to cause a human to drown due to condensation in the lungs (it's a real phenomenon, look it up). Of course if the humidity doesn't kill you the heat would, as I imagine heat indices in excess of 100C.
On the high side, all that moisture, if it was flowing up the mountain ranges, would generate extreme amounts of rainfall, especially considering the cooling of temperature with altitude. One would likely have zones of the "steamy desert", a steppe-like zone, a very hot and steamy savanna-type zone (where the hardier plants would be), followed by a jungle zone more extreme than anything seen on Earth, with high temperatures (perhaps around 30C?), high humidity, and extreme rainfall. Higher up than this, the air may become noticeably thinner, and there would be jungle areas with temps more Earth-like, but with even more extreme rainfall, followed by the tropical highland-like areas, then some subtropical highland-like areas. These places would have thinner air, perhaps approaching Earth-like pressure. This may cut back on the amount of moisture, but I'm not sure .
Your places that would correspond to the tropical and subtropical highland type climates on Earth would have even more extreme amounts of rainfall, perhaps in the form of constant downpours. Beyond this point you may run out of mountain height, and also it would depend on the seasonality of the planet you've created, but I think this is about the highest you want to go, considering snowcaps don't fit into the picture. However, if you had a sudden spike in elevation next to such a steamy place enough to get subfreezing weather, you could have constant pouring snow.
Another thing that may be considered is rain shadow effects on the lowlands and leeward slopes of these mountains. Of course if there is a huge source of moisture on both sides it may not make much of a difference, but there's bound to be less rainfall on the sides of the mountains leeward of the prevailing winds
Quote:
Mars reminds me of Olympis Mons and the intriguing idea of a mountain that extends above the atmosphere. I'm imagining a world with a mountain range so high the atmosphere must move around it, and what kind of climates that might generate.
Such a setup wouldn't make a whole lot of difference on a global scale if it's an isolated mountain like Olympus Mons, but if it were more widespread and the atmosphere were only in rift valleys as in my idea, it may lead to blocked circulation if the rift valleys are not widespread in longitude. On Earth we have large-scale atmospheric circulation between hot and cold regions which help balance temperature out, but on such a world there wouldn't be any intrusions of air from somewhere else, so a subtropical region may stay very hot whereas a polar region would stay cold. Extremes of climate would be commonplace, like Death Valley or the Alaskan Valleys on steroids. A polar valley cut off from any source of tropical warmth may become very cold and stay that way. There's also the issue that atmospheric evolution may be different, and that atmospheric composition could vary between valleys.
Of course on my world there isn't that problem as the canyons and rifts are widespread enough to allow for some air circulation.
Wouldn't a high latitude, extreme low elevation place like this have a persistent inversion in fall and winter (beause the weak fall/winter sun wouldn't be able to warm the surface on the bottom enough) so that it would be actually cold down there?
Also, do you think it could rain in such a place or would its extreme low elevation generate so strong persistent high pressure area over it that it would be impossible to rain there?
That's a good question, but from studies of how "ocean planets" would behave in hotter orbits, it seems like such temperatures would create a thick, steamy atmosphere, but not a runaway greenhouse effect. The studies examined "supercritical" ocean planets with temperatures near the boiling point. Notwithstanding the case of Venus and Gliese 581 c, terrestrial planets which naturally would work differently, I still think 40-50C would be pretty safe as a mean ocean temperature, although not necessarily safe for any humans living near it .
Do you have any links on those studies? I've read otherwise, and I'm rather curious about these studies.
Wouldn't a high latitude, extreme low elevation place like this have a persistent inversion in fall and winter (beause the weak fall/winter sun wouldn't be able to warm the surface on the bottom enough) so that it would be actually cold down there?
Also, do you think it could rain in such a place or would its extreme low elevation generate so strong persistent high pressure area over it that it would be impossible to rain there?
I think there would be precipitation but it would be generated by the high pressure, like a heavy drizzle/mist.
If temperatures were freezing then I guess it would take the form of ice fog and very fine ice crystals.
Take a look at Turpan, China.
The city proper is about 30m above sea level, but some places in the suburbs are 100m BELOW sea level.
The climate is very extreme.
Fascinating!
I wonder if this is the northernmost point (43°N) where high temperatures exceed 100°F any time of year)?
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Extreme Altitude Variation and Thinner Air
.
.
