We learned in school that the earth experiences seasons because it’s tilted on its axis. I get that, but what I can’t figure out is what season would it be if there was no tilting at all?
So if the earth wasn’t tilted on it’s axis what season would it always be in the northern and southern hemisphere?
It would be a season somewhere in between summer and winter. But we wouldn’t be able to call it “fall” or “spring”, because those imply that one season is past, and another is coming. We’d still have some yearly variation due to the changing distance from the Sun, but it’d be small. It would be broadly similar in the northern and southern hemispheres, aside from differences due to the south having more ocean.
It wouldn’t be any season, since “season” implies a transient condition.
Although the tilt of the earth’s axis is at the root of seasonal change, there’s a lot more that goes into making up the seasons we are familiar with. Many of the seasonal markers that we are familiar with - e.g. buds in the spring, dead leaves in the autumn - are functions of the kind of vegetation that predominates where we live, or the migratory/hibernatory behaviour of animals. In other parts of the world, where the ecosystem differs, they experience seasons quite differently, even to the point of experiencing an entirely different cycle of seasons. You may think there are four seasons, but in other parts of the world there are only two - wet and dry - while here in south-western australia there are traditionally six seasons of about two months, with each season characterised by the food sources which predominate.
If the earth had no tilt it’s likely that our flora and fauna would be very different (would we even have deciduous plants, I wonder? Or migratory or hibernatory species?) In such a different ecosystem, we can’t assume the year-round conditions would look anything like any of the seasons that we are familiar with.
I assume there are deciduous plants in the tropics. So seasons are not necessary. You would have temperate zones perpetually stuck in April weather, and the polar regions would be somewhere in the middle too. Some seasonally-influenced weather appterns might not exist. but there would still be much of the weather we are familiar with.
Possibly since there would be no summer melt in the higher latitudes, the poles would be top-heavy with snow that did not have a summer warming to melt in. Perhaps the higher latitudes would have large thick glaciers, a perpetually incipient ice age. The reflectivity of the snow would reduce the sunlight warming at higher latitudes, so we would expect that a lot of the water would be tied up in mile-thick glaciers like the ice ages, but not advancing too far.
As mentioned, there would be no migratory animals, no hibernation. The temperate land would be more like the higher altitudes of tropical mountain chains, cooler but without seasons. Plant and animal life would be just getting by. It might be cool in the temperate zone, but as a bonus you could grow 2 or 3 crops a year.
The earth’s orbit is slightly eccentric, to the point where the sun is closer by 2% and gives more heat in December that June. Perhaps that small variation would trigger minor climate changes at latitudes that mimic some small seasonal variation.
Perhaps.
Yup, lots of differences. No Four Seasons hotels, and Frankie Valli would have been a solo act from the getgo.
it would be called either Auting or Sprum.
there are temperature lags that affect the equinoxes so it wouldn’t be like a perpetual equinox but a temperature in that vicinity by a few weeks. it might be lots of sameness of the type at the equator.
Yes, a young man’s fancy would not turn to love in the spring. They’d have sex on their minds all year round instead.
…oh, wait…
The way I understand it, what we call deciduous trees are the older taxonomy for trees in general, while evergreens are a cold weather adapta
Dunno about that. Pretty much all the native flora of Australia are evergreen, and the place is not notably cold.
Then it would probably be broiling hot all year round in Thailand.
Oh, wait.
Sorry, I had a problem with this device. What I was going to say was the broadleaf deciduous trees can do a lot more work – our boreal evergreens have small needles, and I cannot think of one that produces fruit like a broadleaf. The deciduous trees lose their leaves because otherwise the snow load would snap them like, umm, twigs. In the tropics, there is not much likelihood of a major snow load, so they would just never lose their leaves. Without seasons, where ever deciduous trees could grow, they would simply never have to decide, because the threat of snow would be trivial and transitory.
There are seasons in the tropics, but they are wet and dry seasons. They are also determined by the position of the Intertropical Convergence Zone, and hence the movement of the sun back and forth across the equator. Without the axial tilt, wet and dry seasons also wouldn’t occur.
There are lots of deciduous trees in the tropics, but they lose their leaves in the dry season to save water. Without seasons, most plants would be evergreen, even the broadleafed ones.
A vertical Earth would almost certainly be colder than our tilted Earth. On vertical Earth, high latitudes would get almost NO insolation–the Sun generates little warmth when near the horizon–and would get incredibly honking cold.
[On our tilted Earth, high latitudes get a fair amount of insolation in summer, so they periodically warm up.]
Permanent twilight and cold at high latitudes would have ripple effects, since more ice would form in high latitudes, causing higher albedo and more reflection of heat, causing even more ice, and so on. Most likely, given distribution of continents anything like today, we would have a permanent Ice Age.
Low latitudes might still be pleasant–maybe more so than today–but there would likely be an extreme temperature falloff as you moved away from the equator.
This may be the first time I’ve encountered that word in the wild since learning it in the fourth grade.
To everything - turn, turn, turn
There is a season - turn, turn, turn
Well, no …
/Trying to visualize this.
Does this mean that both the north and south poles would be in perpetual twilight, with the sun skimming the horizon all the way around, twenty-four hours a day?
yeah, this was my thought in post #4. Without summers to melt accumulated snowpack, the “snow line” would probably work its way further south. With no melting, the accumulation would turn into a glacial source feeding into much more southerly areas. Likely the poles would be top-heavy with ice and global sea levels would be much lower. That top-heavy ice would produce mile-thick glaciers oozing into the temperate latitudes.
Theoretically, yes; if there was absolutely zero tilt. As you travel further north, the sun would rise in the east arc lower across the sky, and set in the west. near the pole, The sun would never get completely above the horizon, it would skim along and start to sink. At “night” part of the disk would still peek above the horizon in the north. right at the pole, you would see the disc of the sun peeking over the horizon perpetually circling around the horizon.
Sky-wise, everything would be like it is now at the equinoxes, year-round. So yes, the sun would forever skim the horizon at the Poles. Weather-wise, though, it would be colder; something like perpetual winter.
Which would probably also cause extremely intense hurricanes and other storms, which is how heat is transferred between the tropics and higher latitudes. A more extreme gradient should produce more extreme weather.
In the North Temperate Zone “evergreen” is often regarded as being synonymous with pines and other needle-bearing gymnosperm trees, because these are virtually the only ones that keep their leaves through the winter. (There are some others like hollies.) While most of these gymnosperms don’t have fleshy fruits, some do, likeyews and junipers.
In the wet tropics (and some temperate areas like Australia) most of the trees, including angiosperms and gymnosperms, are evergreen.
