Possibility of flipping short days in winter and vice-vas

[Crossroads Inc.]

Basically would it be possible, depending on Axial tilt and Planetary orbit, to have a season cycle of Long days during winter, and short days during the summer? Very simple question I know, but curious of the possibility of it.

[Broomstick]

Yes, if you had an orbit in an extended oval such that the most distant part of the orbit coincided with one of the hemisphere's axil tilt toward the sun.... although the season on the other hemisphere would be highly extreme. Such a situation probably wouldn't be stable over the long term, either, so you have periods of that effect on first one hemisphere then the other.

[LaCroix]

Day lenght difference comes from the inclination of axis.
Tilted away - short days. Tilted towards - long days.
Long days = long exposure to sunlight (lots of heat)
Short days = short exposure to sunlight (less heat)

You would need a highly elliptical orbit to achieve that effect, where you are a lot closer during winter of one hemisphere than during summer. But there are some problems:

For earth, you'd need to be a god bit closer during northern hemisphere "winter", and a lot further away during summer. But the other side? During "winter", it would have summer, and be scorched. And during "summer", it would be a frozen glacier, as their winter would be a lot worse. That would also affect temperature on the northern, moderately temperated hemisphere, but if the orbit is tailored just right, you'd get Earth-like seasons there.

Basically, only one hemisphere of that planet would be habitable, with moderatte weather, but wrong day length. For the other, you'd have weather oscillating between Sahara/Death Valley and Sibiria/Antarctica on that hemisphere, with a brief period of acceptable during mid spring/autumn. Vegetation? Probably little to none. Just a desert that freezes over during winter. Animals? Maybe ones with a crazy hibernation pattern.

[Simon_Jester]

It would be a lot easier to just have a planet with near-zero axial tilt and no seasons.

It would be incrementally less difficult to have a planet with no seasons, but with an orbit elliptical enough that exposure to sunlight created them to a limited degree (say, eccentricity to the tune of 10% of the orbital radius).

Either way, though, day length would be effectively constant.

[Also as a side effect, in any one place the sun always follows almost exactly the same track in the sky, which has consequences for things like building design and plant growth.

[Broomstick]

Basically, only one hemisphere of that planet would be habitable, with moderatte weather, but wrong day length. For the other, you'd have weather oscillating between Sahara/Death Valley and Sibiria/Antarctica on that hemisphere, with a brief period of acceptable during mid spring/autumn. Vegetation? Probably little to none. Just a desert that freezes over during winter. Animals? Maybe ones with a crazy hibernation pattern.

I disagree about the vegetation. Let's take Death Valley as an example:



There's actually a LOT of life in Death Valley, it just stays dormant until conditions are right. Just as a lot of temperate and arctic zone plants and animals go dormant/hibernate/migrate during the winter. You don't see that in Antarctica because that continent just never has decent conditions for terrestrial life at our size, other than coastal sealife (even so Emperor Penguins manage to survive the winter while incubating eggs and raising chicks). Your hypothetical extreme hemisphere would have life that went dormant during the extremes and live at a fast pace during times and conditions suited to making a living and raising young. The plants would either grow like mad and quickly go to seed (that's what happens in Death Valley), or be able to go dormant for long periods. The animals would either hibernate/estivate, migrate, or have some sort of means of coping (gorging during times of plentiful food, living on reserves during lean times). If life is possible, life will adapt to the conditions and for half the year the situation might not be too bad at all, really.

Don't forget - land masses, ocean currents, and wind patterns also affect climate to a large degree. I'm not enough of a planetary scientist to run all the angles, but various configurations of land and sea could result in considerable moderation of extremes.

[LaCroix]

I disagree about the vegetation. Let's take Death Valley as an example: *snip*

On this planet, the "Death valley" regions would be even worse, due to the much closer sun.

And Death valley goes from HOT to moderate, while Antarctica might change from freezing to barely thawing.
Also, oth only see half of the temperature swing that this hypothetical planet would witness in some regions.
If you have a regular 6 month pattern from hot as hell to hell frozen over, I think it would be too much of a contrast for life to take hold.
In the moderate regions, maybe, but once you get far enough, it's simply too much.
I do concede that it won't be all barren, but there would be a wide belt that is largely inhabitable.

Funnyly enough, the south pole could be more habitable than the central regions of the hemisphere. While in winter, the south pole would give Antarctica an ass-whooping, in summer, that region could be having a climate akin to northern Scandinavia.
This also means that seasonal sea levels could be funny on this planet, though.

Interesting question : It would be a far stretch, but could they have a completely unrelated ecosystem there, seperated by the inhabitable regions?

[Broomstick]

I disagree about the vegetation. Let's take Death Valley as an example: *snip*

On this planet, the "Death valley" regions would be even worse, due to the much closer sun.

And Death valley goes from HOT to moderate, while Antarctica might change from freezing to barely thawing.
Also, oth only see half of the temperature swing that this hypothetical planet would witness in some regions.
If you have a regular 6 month pattern from hot as hell to hell frozen over, I think it would be too much of a contrast for life to take hold.

There are seeds on our planet that can withstand everything from the heat of a forest fire to being frozen with dry ice, it is certainly possible for seeds to withstand both extremes.

A 12 month cycle for freeze-burn-freeze might be tight, but not impossible either. Plants in both the Arctic and places like Death Valley germinate, grow, reproduce, and set seed in a matter of weeks. The champion short life cycle plant is, apparently, the common duckweed which allegedly can complete its lifecycle in 30 hours under ideal conditions (fortunately, conditions are seldom that ideal otherwise the entire planet would be made of duckweed).

One reason you have such a lack of growth in Antarctica is because it never gets warm enough, but the other problem is that is also dry - it's basically a cold version of Death Valley, it's one of the driest deserts on the planet. Double-whammy, yet life still has a foothold. Despite current conditions, there are two flowering plants native to the southernmost continent (Antarctic hair grass, and Antarctic pearlwort) along with mosses, lichens, and liverwort that total a couple hundred species. And, of course, you have all those animals that use the land but live off what's in the sea. If the place would warm up a bit more for a few weeks a year and get a little more precipitation you'd probably have even more plant life and possibly some critters living off it.

In the moderate regions, maybe, but once you get far enough, it's simply too much.
I do concede that it won't be all barren, but there would be a wide belt that is largely inhabitable.

Uninhabitable for the likes of us, yes, but life is surprisingly adaptable and tenacious.

This also means that seasonal sea levels could be funny on this planet, though.

Yep.

Interesting question : It would be a far stretch, but could they have a completely unrelated ecosystem there, seperated by the inhabitable regions?

Probably not a completely independent origination of life, but yes, you'd probably have radically different ecosystems in the different climate bands. It's like the critters that live in hot springs or black smokers on our planet - they are related us back a few hundred million to a billion years or so, but they're unable to live in our environment and vice-versa. I would also assume a LOT of migratory lifeforms following their ideal conditions around the planet as the seasons shifted.

Some locations might have three ecologies - a very hot ecology, a moderate temperature ecology, and an arctic ecology with the three groups hibernating during unfavorable to them conditions and "waking up" for only a portion of the year, with each group having its own plants and animals.

[Irbis]

On this planet, the "Death valley" regions would be even worse, due to the much closer sun.

And Death valley goes from HOT to moderate, while Antarctica might change from freezing to barely thawing.
Also, oth only see half of the temperature swing that this hypothetical planet would witness in some regions.
If you have a regular 6 month pattern from hot as hell to hell frozen over, I think it would be too much of a contrast for life to take hold.

How about -70 to +40 degrees Celsius, difference of over 100°C? Last time I checked, Siberia isn't barren and at that temperature range, difference even larger, say 150°C, -90 to +60, is going to be largely academic, limited only by water access. You'd need extremophile organisms but nothing that we don't have here already.

Interesting question : It would be a far stretch, but could they have a completely unrelated ecosystem there, seperated by the inhabitable regions?

Probably. Though, you can make case it's already happening on Earth.

[Broomstick]

Oh, sure - the black smoker ecologies can't exist in our "normal" environment. The hot spring extremophiles can't exist outside those hot springs. And so on and so forth.