Will length of season vary depending on earth's orbit?

[heng]

lazy-sun-burn-fueled lunchbreak discussion:

Assume we are able to move the Earth further away from the sun, still in (more or less) circular orbit, to counter global warming.

Ignore whether it would have the desired effect, ignore how it is done (lots of swing-by maneuvers, for example), ignore the turbulence effects on other planet's orbit.

The year will be longer. Clearly.

Question:

Will the seasons change in length or stay the same, instead move around on the calender?

[Superfluous J]

lazy-sun-burn-fueled lunchbreak discussion:

Assume we are able to move the Earth further away from the sun, still in (more or less) circular orbit, to counter global warming.

Ignore whether it would have the desired effect, ignore how it is done (lots of swing-by maneuvers, for example), ignore the turbulence effects on other planet's orbit.

The year will be longer. Clearly.

Question:

Will the seasons change in length or stay the same, instead move around on the calender?

The "seasons" will stay 1/4 of the year, so will grow as the year grows. Who knows if they'll resemble the seasons we have now but probably. Mars has visible Summer/Winter seasons, after all.

They'll still generally stay where they are. What we call "Summer" in the Northern Hemisphere starts on the longest day of the year, and ends halfway down to the shortest day of the year. Winter is the same only it starts on the shortest and goes up to halfway to the longest. Lag in how the hemisphere heats and cools causes the hottest and coldest days to start after the longest and shortest days of the year, and that shouldn't change all that much within reason, especially if we're magically moving the Earth to cool it down.

And yes, I'm ignoring that it wouldn't work, we couldn't do it, and if we figured out a way to do this thing that wouldn't work, it'd likely kill us

[andrewas]

The seasons are primarily caused by the Earth's tilt. Earth's orientation does not change throughout the year, only its position relative to the sun. On one side of the orbit, the north pole is tilted away from the sun. Six months later, the north pole is tilted towards the sun. The formed gives us northern winter, the latter gives us northern summer.

So, yes, the length of seasons will change with Earth's orbit.

[Nibb31]

Will the seasons change in length or stay the same, instead move around on the calender?

Seasons are not related to the Earth's orbit but to its tilt, which explains why the southern and northern hemisphere seasons are inverted.

Distance from the sun has a much smaller effect than the angle at which solar rays hit the atmosphere.

Edited August 21, 2015 by Nibb31

[peadar1987]

The "seasons" will stay 1/4 of the year, so will grow as the year grows. Who knows if they'll resemble the seasons we have now but probably. Mars has visible Summer/Winter seasons, after all.

They'll still generally stay where they are. What we call "Summer" in the Northern Hemisphere starts on the longest day of the year, and ends halfway down to the shortest day of the year. Winter is the same only it starts on the shortest and goes up to halfway to the longest. Lag in how the hemisphere heats and cools causes the hottest and coldest days to start after the longest and shortest days of the year, and that shouldn't change all that much within reason, especially if we're magically moving the Earth to cool it down.

And yes, I'm ignoring that it wouldn't work, we couldn't do it, and if we figured out a way to do this thing that wouldn't work, it'd likely kill us

I don't know what part of the world you're from, but if winter doesn't start until the 21st of December, I think I might have to move there!

[cantab]

If the orbit stays circular the seasons will still be quarters of the new, longer year.

If on the other hand the orbit is elliptical things get interesting. When the axial tilt dominates you get seasons that are no longer equal length because of the planet's varying speed in its orbit, and the seasons in the northern and southern hemispheres cease being mirror images. That is the case on Mars.

If the orbit is elliptical enough that that dominates the seasons you get summer and winter and the same time everywhere. The planet spends most of its orbit far from the Sun and is only close for a short portion, again due to varying orbital speeds. That means if summer is normalish winter will be very long and cold, whereas if winter is normalish summer will be scorching hot but brief. Either way it's likely the ecosystems of Earth could not survive, though life in general could.

And if the axial tilt and orbital eccentricity were balanced just right you could get one hemisphere having strong seasons and the other having virtually none. Now that would be an interesting world. The high latitudes in the season-free hemisphere would have ecosystems combining the cool temperature adaptations of Earth's high latitudes with the non-seasonal features we only see in our tropics.

Edited August 21, 2015 by cantab

[KerbMav]

I don't know what part of the world you're from, but if winter doesn't start until the 21st of December, I think I might have to move there!

Just because the weather can be winterly - winterly as in story books from our childhood - does not mean winter starts with the first snow.

[peadar1987]

Just because the weather can be winterly - winterly as in story books from our childhood - does not mean winter starts with the first snow.

Seasons aren't rigidly defined. In Ireland, as a result of the Celtic influence, the seasons are:

-Winter: 1 November to 31 January

-Spring: 1 February to 31 April

-Summer: 1 May to 31 August

-Autumn: 1 September to 31 October

Each season is based on having an equinox or a solstice as its midpoint. I'm sure it differs elsewhere because of varying cultural factors, but a "season" isn't something that has a precise, universal scientific definition.

[MinimumSky5]

Each season is based on having an equinox or a solstice as its midpoint. I'm sure it differs elsewhere because of varying cultural factors, but a "season" isn't something that has a precise, universal scientific definition.

As an Englishman, I know how odd it is to think that winter starts on the 21st December, but it is that rigidly defined in astronomy, the only difference being that that is the start of summer in the southern hemisphere.

[KerikBalm]

FWIW, I think it makes more sense to have the solstices and equinoxes as the middle of seasons, rather than endpoints...

but to the OP...

It should be obvious to anyone who really understands the cause of the seasons, that their length scales with the length of the year, and the beginning of a season will be at the same proportional time during the year.

This is assuming that the eccentricity doesn't change.

In a highly eliptical orbit, things change a lot

[peadar1987]

As an Englishman, I know how odd it is to think that winter starts on the 21st December, but it is that rigidly defined in astronomy, the only difference being that that is the start of summer in the southern hemisphere.

WHAT?! This is just plain wrong. Forget that silly Pluto debate, we should be on to the IAU about their stupid, stupid definition of seasons immediately!

[Trann]

I do like the solstice/equinox markers to define an "official" start of the "astronomical season" because it's based on the ecliptic crossing the celestial equator and the peak day and night periods. It has nothing to do with local weather and nor should it: weather is far too dynamic. An exceptionally warm or cold spell could push back a season by weeks or longer, making the mid-point definition moot.

As an amateur astronomer, it's a nice universal (sorry, Sol-based) constant to have.

[Superfluous J]

I don't know what part of the world you're from, but if winter doesn't start until the 21st of December, I think I might have to move there!

FTR, it starts getting cold enough for jackets here in late September, and while there is usually one nice weekend in November (nice = can walk outside for indefinite periods of time without your face freezing) it's cold from October through March, and usually even into April but by then we don't care and go out anyway. October snows are by no means common but neither are they rare.

However that all said, January and February are easily the 2 coldest months, and February is always the worst. March is usually pretty bad too, but like November can sometimes have a nice weekend just stuck in between blistering cold weeks.

But I wasn't talking about any of that. I was talking about the officially unofficial designation of seasons that others have already specified and that of all the definitions, I personally prefer: having them start at the appropriate equinox or solstice.

[PakledHostage]

If on the other hand the orbit is elliptical things get interesting.

For what it is worth, our Earth's slightly elliptical orbit already does affect the length of the seasons a bit. In the northern hemisphere they are as follows (number of days between solstices and equinoxes):

Winter: 88.99 days

Spring: 92.75 days

Summer: 93.65 days

Autumn: 89.85 days

So the southern hemisphere's summer is about 5 days shorter than the Northern hemisphere's summer because the Earth reaches perihelion (highest orbital angular velocity) on about January 3rd and aphelion (lowest orbital angular velocity) on about July 4th. And because the length of time between the equinoxes and solstices has noting to do with how we record time on our calendars, the length of the seasons is not affected by leap years.

[Camacha]

The definition question really does not interest me, because it will invariably mean lots of scientists, laymen and institutions that have a reasonable say or nothing to do with the matter altogether fielding their opinions in ever less graceful ways. It will be a mess. A more practical and, to me, more interesting question is how nature will cope. Will different animals and plants adapt seamlessly, will some cope because they happen to have the right mechanisms in place and will some perish, or will it mean general upheaval and a huge realignment of all things growing.

If I were to guess I would say it is the second option, since different organisms employ different ways of detecting or predicting seasonal changes. Some seem more time based, while others are just triggered by the circumstances. Trees, for examples, shed their leaves mostly cued by the temperature and light. Both will change with the longer seasons, so it seems the trees will adjust just fine. Gestations periods, on the other hand, are often timed with the seasons and availability of resources, so that might cause some minor or major problems, depending on the species and exact mechanism in each organism.

[YNM]

I'll define seasons out of changes in absolute insolation (no cloud and average albedo), out of how much the Sun gives a tangent flux (or some number equal to the tangent flux) to a certain part of the planet in a day.

This certainly brings four things in :

- Latitude of said place on Earth's surface

- Axial tilt wrt orbital plane

- Location of nodes between orbital plane and rotational plane

- Eccentricity of orbital plane (I'll only consider extreme cases, Earth's 0.0167 is way too small to fare with 23.5 tilt)

So, I'll try to answer :

Perfectly circular orbit w/o tilt: no season.

Perfectly circular orbit with axial tilt: equal length four season at high latitude, two season at equator.

Eccentric orbit w/o tilt: planetwide season. Possibility of freezing atmosphere at extreme limits. Also correct for a highly inclined orbit (e > 0.2)

Eccentric orbit with tilt, nodes at Ap&Pe: equal length four season, though the different direction will certainly produce some difference. Two season still at equator, possibly an arid and wet side (east-west fashion) unless it induces winds instead.

Eccentric orbit with tilt, nodes halfway between Pe/Ap: distinct season between hemisphere, one get a hot summer while the other get cold winter and vice versa. Two season at equator, arid areas probably concentrated in one hemisphere.

[AcidSludge]

Do we add new months with cool names, or do we just add days to the months? Isn't it awful to wait longer between two christmas or birthday presents?

And oh the bureaucracy!

[Superfluous J]

Do we add new months with cool names, or do we just add days to the months? Isn't it awful to wait longer between two christmas or birthday presents?

And oh the bureaucracy!

Easy solution, make the year 2x as long and just repeat everything twice a year. One Christmas will be all cold, and one will be all warm. In BOTH hemispheres!

You're WELCOME, Australia.

[Kerbart]

Each season is based on having an equinox or a solstice as its midpoint. I'm sure it differs elsewhere because of varying cultural factors, but a "season" isn't something that has a precise, universal scientific definition.

The logic of putting an equinox or solstice in the middle of a season has merit, but (and I hope this doesn't cause the wrath of the moderators, but if it does, I'm sorry) the downside of that is that the beginning/end of each season is a lot harder to measure.

In ancient times (again mods, sorry if this is considered rude or polarizing) the only only calendar was the position of the sun and the moon and druids, priests (this might be considered politically incorrect, my apologies) and other wise people would declare the time for harvest, planting, etc based on events that were easy to measure: equinoxes and soltices. Hence, seasons tend to start/finish with those, instead of having them as midpoint, as much sense it makes.

[jwenting]

Easy solution, make the year 2x as long and just repeat everything twice a year. One Christmas will be all cold, and one will be all warm. In BOTH hemispheres!

You're WELCOME, Australia.