zompist bboard

Disclaimer: This is all the work of a complete amateur, following another complete amateur. Hence the thread title.


Why Climate?

For anyone with a bottom-up approach to conworlding, climates are an essential starting point. Directly or indirectly they affect just about everything, especially plant- and wild-life, which in turn governs agriculture, which in turn forms the basis for how cultures develop. Aspects such as winds and surface ocean currents affect pre-modern travel and trade. Finally, working out climates is an excellent way to get a "big picture" look at your conworld.



Getting Started

What Kind of World?

For the purposes of this guide I'm dividing worlds loosely into three categories - Earthlike, non-Earthlike and Fantasy. There is also the issue of how hard you want your science to be - hard science follows the physical laws of the world (be they real world physics or conphysics) as much as possible, while soft science is more flexible. Also, the softer your science, the more likely it will be that you can apply the Earthlike model without worrying too much about little details like the fact that your world has twenty moons and orbits a binary star system.

Geoff's model for working out climates is for an Earthlike planet, and I'm not about to write guides for all the many and various other possibilities. Instead I'll be providing hints and tips on how to go through the processes described there, and how to adapt them for other world types.


Earthlike Worlds
In theory there's nothing to stop you from applying an Earthlike model to any world. In practice, this usually means that your world is shunted towards the softer end of the scientific scale. Earthlike Worlds:

1) Have a stable orbit around a single star, in the habitable zone
2) Are around the same size and composition as the Earth*
3) Have a similar atmospheric composition to Earth
4) Have a similar day length to Earth
5) Have a similar axial tilt as Earth (between 20 and 30 degrees)
6) Have a single, large satellite; this stabilises the axial tilt*
7) Are non-magical, or do not have magic powerful and prevalent enough to effect the large-scale physical cycles of climate*

* These can be conveniently ignored without things becoming too unscientific

Non-Earthlike Worlds
Non-Earthlike worlds are "everything else", given real world physics. In a very hard science setting different sizes and compositions will affect gravity, anything other than a single, large satellite will probably destabilise the axial tilt over the long term, and it just gets worse the more you change. Non-Earthlike worlds include:
Planets orbiting multi-star systems
Planets with extreme axial tilts
Planets with very short or long days
Planets with very short or long years
Worlds that are moons

Fantasy Worlds
For the purposes of this guide, fantasy worlds are those that a) have magic powerful and prevalent enough to effect the large-scale physical cycles of climate, and/or b) run on their own conphysics. Nothing can be taken for granted on these worlds, especially if you're trying to design an internally consistent set of conphysics (the fantasy equivalent of hard science).


Summary:
* What kind of world do you have? Earthlike, non-Earthlike or Fantastic? Hard or soft science?


Case Study: Menducia
Menducia is the nightmare scenario: a relatively hard-science fantasy world. It has its own laws of physics, with a hefty dose of animism. It's geocentric, with a sun orbiting the world. It's only a quarter mapped, with most of the world's surface permanently designated Oceanus Incognitus. Still, working from the bottom up, we can work out the basic principles that drive climate there.

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

This is good stuff. Really good stuff.

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http://rpusa.info/platform.htm
http://www.stardestroyer.net/
http://www.projectrho.com/rocket/

moar

Agreed.

Moar!

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http://rpusa.info/platform.htm
http://www.stardestroyer.net/
http://www.projectrho.com/rocket/

Not only that, it's a good candidate for an article in a putative centralised source website, a one-stop shop for budding conworlders who don't want to have to figure all this out from several places at once.

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I'm using both hard-science, and non-Earthlike (though trying to keep it as close as possible).

Here's the breakdown:
Ti Hpimahttanqmin is a K0V star (which makes it slightly different than our own, which is a G2V; the first letter is the spectral type, the number is the absolute magnitude, and the second letter is the luminosity class). The star is much longer lived than G-stars. And unlike typical K-type stars, has an atypical mass--this phenomenon is well documented within the star cluster that this star exists. It gives off a yellow-orange light, as opposed to a much stronger yellowish-white light like our own sun.

The star has a sister, an unusual 72 Jupiter-mass L-type brown dwarf (that is, it has a stable deuterium fusion, but also contains massive amounts of complex chemicals in its atmosphere; there is debate whether or not it's a type-L:T) It is virtually invisible, except on near-infrared spectrums. While it is as young as the main-sequence, the formation of the proto-star disrupted its process.

The mass and unusual complex-nature of the main star is related to the presence of heavier-than-iron elements within the star cluster; it is uncertain why these heavier elements have not disrupted star formation, and why they are rare on planetary surfaces, but not in stars.

The planet sits approximately 1.27 AU from the star. It has a near-perfect eccentricity (approximating 0), but possesses a radical 45 degree tilt. It has a small series of satellites, though the largest and most notable one is its primary moon, possessing a rich methane-nitrogen-carbon dioxide atmosphere, complex weather systems (for its size and mass; it's approximately 2 lunar masses), liquid ice mantle with a rich convection system (which includes such features as ice-based tectonic plates, boiling-water volcanoes). It's core is a mix of iron and uranium, and has a large magnetosphere that interacts with the planet's.

Primarily, though, I need to figure out the planet's total map, landmass, etc., and create a weather map and climate map. It is very high on certain green-house gases, and it equalizes its own temperature (despite being farther than our own planet, and its star is much cooler.)

I also wanted to add a few peculiarities, such a high-altitude supra-atmosphere system layered on top of its atmosphere that eroded its planetary ice ring (a high-altitude supra-atmospheric storm could have caused enough problems to "boil" all the ice away).

And Anguipes, I'm always interested in your conworld . Your basis of internal physics is quite intense.

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KneeQuickie | Proto-Deithas Reference Grammar

Basic Principles

Earthlike and Non-Earthlike Worlds

The first thing to get straight are the basic principles that govern climate in your conworld. For an Earthlike planet, Geoff has a handy list:



Most of these principles also affect non-Earthlike worlds. Remember that the terms hot/cold and high/low pressure are relative - a planet with a dense atmosphere may be generally "high pressure", but will still have areas of relative low and high pressure and winds blowing from the latter to the former.

1) changes when there are multiple suns, or if your world has significant internal heating. Generally, internal heating is related to mass; a greater mass means more internal heating. Earth's internal heating is not enough to interfere with its solar-heat driven climate, but the weather of gas giants is driven more by internal heating than solar heating. Moons may experience tidal heating due to gravitational stresses from a nearby massive planet (a Solar System example is Io, one of Jupiter's moons).

2) depends on the presence of large areas of liquid water and rocky land. On a more basic level, what you need to know is the specific heat capacities of areas of your world. The higher the specific heat capacity of a material, the slower it heats and cools. On an Earthlike planet with oceans and rocky continents, the oceans heat and cool slower than the land because water has a relatively high specific heat capacity. If your world has a significantly different composition, you will need to find out at least a vague relative idea of the specific heat capacities involved.

3), 4) and 5) are universal principles of the movement of gases, and will apply to any atmosphere.

6) will depend on how fast your planet rotates, and in what direction. The faster the rotation the stronger the Coriolis effect, and the direction of rotation governs the direction in which things are deflected. A west-to-east rotation (like Earth's) will deflect clockwise in the northern hemisphere and anticlockwise in the southern, while an east-to-west rotation will deflect anticlockwise in the northern hemisphere and clockwise in the southern.

7) applies because air, and its associated water vapour, cools as it rises until it reaches a point (the dew point) where it turns back into liquid water. The same principle forms clouds and precipitation of many different substances all over the Solar System, depending on the local temperatures and atmospheric compositions (ammonia clouds on Jupiter, nitrogen clouds on Triton, sulphuric oxide clouds on Venus etc.)


Fantasy Worlds

In fantasy worlds none of these principles can be taken for granted. Instead, one has to go right back to the most fundamental considerations:

What heat source(s) does your world have? What causes heat/temperature variation, and why?

Do different parts of your world heat and cool at different rates? If so, how and why?

What principles govern atmospheric movement? Does heat drive air movement, or some other force?

What causes rain and other precipitation? Is water vapour carried by the air, or is some entirely different principle at work?


Summary:

Don't try to take things too far at this stage. You don't need to know all the consequences yet, just the rules. As many things as I can think of that effect each individual stage (such as the effect of planetary rotation on winds) will be dicussed at the appropriate time.

for an Earthlike world:
The work has already been done for you. Lucky you!

for a non-Earthlike world:
Start to think about where the principles of your world might differ from the Earthlike model. General, constant differences from Earth in factors such as temperature or gravity are less important at this stage, though it might be a good idea to make a list of all the ways your world differs from Earth for reference.

for a Fantasy world:
Think about what forces exist in your conworld an how they might effect the building blocks of climate - heat, winds and rain. Try to get a picture of the basic principles involved - their far-reaching effects can come later.



Coming up: Case Study

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

Case Study: Menducia

Ignoring the tricky question of animism (whereby physical "things" have an animating "will" that can manipulate the physical, even against the normal laws of elemental motion), the basics of Menducian physics runs on the elements. Menducian elements are less materials than "the property of a point in space at a point in time". The Menducian cosmos is best visualised as a very complicated cellular automaton - at any given point in time each point in space is assigned a value (element), nothing truly moves, but each configuration gives rise to the next predictably via certain rules. The imagehereis a handy guide to the names of the elements and how they relate to each other.

However, the specifics of this are the Menducian equivalent of molecular physics - we want a slightly broader look. On a larger scale Menducia operates a lot like the real world, at least in that there are "objects" that "move" (like a glider in a cellular automaton) according to certain "forces" (generally derived from the elemental structure of the object, but also related to the elements surrounding an object).

The basic structure of the cosmos Menducia finds itself in is this: Menducia itself is a large central concentration of Earthy elements in a sphere about the size of Earth, with a layer of Watery elements (the oceans, and to a lesser extent the atmosphere) around it. That is suspended in a vast area of Airy elements (outer space). Other, minor bodies are suspended in the Airy layer, including Menducia's many small moons and the sun, a large concentration of Fiery elements that also orbits Menducia. The sun also has two tiny "solar companions" orbiting it, also composed of Fiery elements. Beyond that the specifics are unknown, and fortunately, not relevant.


What heat source(s) does your world have? What causes heat/temperature variation, and why?

In Menducian physics, Heat is a point on the elemental map. The closer an element is to this point (between Fire and Air), the naturally hotter it is. Air and Fire are therefore naturally hotter than Earth and Water, with Mud (sitting opposite Heat) the coolest element. However this only applies to pure elements, which are rare on large scales. Most objects and materials on a human scale are mixtures, which can have more or less Heat and hot elements added or subtracted (resulting in a corresponding change in the object's properties).

The only major source of Hot/Fiery elements on Menducia is its sun (the solar companions are too small to have significant effect). On the whole Heat tends to radiate away from the planet into space, but it travels at such a rate from the sun that it overcomes the general repulsion (partly to do with it being very pure, at least at the outset - as it travels towards Menducia it reacts with the Air and becomes less so, and so slows down. As it reaches the atmosphere (Air/Water boundary) it's often reacted and diffused enough through other elements that the force pushing it away from Menducia has been weakened considerably, but there has still been a considerable shift in the local elemental structure towards Heat.)

Temperature variation comes from two very familiar cycles - the day (the rotation of Menducia on its axis, so that any one point on the surface may be facing towards or away from the sun), and the year. The year is the time it takes for the sun to make a complete orbit of Menducia. It does so on a plane at an angle to the plane of Menducia's equator - this, rather than an incline in Menducia's axis of rotation, causes seasonal variations in the amount of sunlight .

(All this is mathematically relative - what causes seasons, on Menducia or Earth, is the angle between the plane of the ecliptic and the plane of the equator. If we took the Earth as a stationary point, with the axis of rotation at 0 degrees, and measured the movement of the Sun relative to it, we'd end up with a similar picture. Equally you could make the Menducia system heliocentric, in which case its axis of rotation would be inclined relative to the plane of its orbit - just like Earth's).

There is a third cause of large scale temperature variation. The angle of the sun's plane is not fixed, and changes slowly over billions of years. If I wanted to record Menducia's climate over millions of years I would have to take this into account. Fortunately I only want a picture of recorded history, about 10,000 years, and there won't be significant variation over that period.


Do different parts of your world heat and cool at different rates? If so, how and why?

Due to their differing elemental properties, land and sea react to heat differently. While the oceanss are "naturally" warmer than the land, they have less capacity for Heat - the addition of Heat to Water quickly produces light elements that radiate away from the main body of water, keeping its temperature relatively stable. Earthy elements on the other hand can soak up a lot more Heat before elements light enough to float away are formed, but also repel and lose Heat faster than Water. So, the land heats and cools faster than the oceans.


What principles govern atmospheric movement? Does heat drive air movement, or some other force?

Menducia's atmosphere is a mainly Watery/Airy mix of elements. If it was pure Water/Air, its movement would be highly unpredictable. Fortunately, "light"/"hot" (strictly, Fiery) and "heavy"/"cold" (Earthy) elements also play a part. Hotter parts of the atmosphere rise (are repelled by the Earthy core of Menducia), while colder parts sink (are attracted down).

The further hot air rises, the more Fiery elements it loses as they escape into the upper atmosphere and eventually, space. So hot air cools as it rises, then sinks back down where it picks up excess Fiery elements from the land or oceans, and rises again.

Sinking air eventually hits the land or ocean and spreads outwards from there, picking up heat (and over the oceans, moisture) as it goes. This causes a general flow of air from colder areas to hotter ones, at least in the lower atmosphere.

As Menducia is a rotating frame of reference, all this movement will be subject to a Coriolis effect.


What causes rain and other precipitation? Is water vapour carried by the air, or is some entirely different principle at work?

Watery elements are carried in the atmosphere, and fall as rain when they become heavy (less Fiery/more Earthy) enough. This happen particularly when hot air rises and begins to lose its Fiery elements (see above). Cold, sinking air has generally already lost much of its Watery content, and will rarely produce precipitation. Hot air can also carry more Water than cold air, following a similar principle to that which governs how much Heat can be held by Earth vs Water - Hotter mixtures are lighter, and so can bear more heavy elements to be added to them.


In summary, the basic principles driving Menducian climate are:

*All heating comes from the sun
*Water heats and cools more slowly than land
*Hot air rises, cold air sinks
*Winds flow from cold-air areas to hot-air ones
*Corilolis effect deflects winds to the clockwise in the Northern hemisphere and anticlockwise in the Southern hemisphere
*Rising air is conducive to the fall of precipitation, sinking air is not
*Warm air carries more moisture than cold air

This should all look eerily familiar.

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

Heat Cycles

For any climate driven by heat, long term cycles of temperature will be the basis for seasons. Earth has a single, simple cycle: the changes in day length (and therefore time in the sun) caused by the axial tilt as the planet orbits around the sun. This cycle, and any similar one, produces a simple sine wave pattern - a hot extreme when a hemisphere points towards the sun, a cold extreme when a hemisphere points away from the sun, and a steady change from one to the other.

Differing axial tilts will change the severity of the extremes, but not the basic pattern. A 90 degree axial tilt will produce a world with massive extremes of temperature - on any one point, constant sun (no night) for half the year, and constant darkness (no day) for the other half. A 0 degree tilt will remove seasonal variation entirely.


Tropics and Polar Circles

The tropics are the areas that experience, at least once a year, the sun being directly overhead. The Polar Circles are the areas that experience constant sunlight for at least one full rotation of a planet on its axis ("day") (and conversely, one full day without sun).

The limit tropics will be at the same degrees of latitude (above and below the equator) as the degree of the axial inclination. The polar circles will be the same distance from the poles, 90 degrees minus the axial tilt.

Here is a (very) brief summary of the effects of different axial tilts:

0 degrees - No seasonal variation in day length or heat.

Up to 23.5 - Less seasonal variation than Earth, and affecting fewer areas.

23.5 to 45 degrees - More seasonal variation than Earth, and affecting greater areas

45 degrees - Relatively sharp cut off between a hot equatorial region (-45 to 45 lat) and a warm/cold polar region (everything else).

Over 45 degrees - A hot equatorial zone, a warm/cold polar zone, and an interzone where the two overlap that experiences extremes of heat and cold. Axial rotation becomes less and less significant in determining light/dark cycles; position in orbit begins to take over (i.e. long periods of midnight sun/no sunrise in many areas).

90 degrees - Exposure to sunlight is based entirely on position in orbit, day (axial rotation) plays no part. Light/Dark and Hot/Cold cycle will be the same, causing massive extremes due to constant presence/absence of heating. Life unlikely due to extreme variability in any one location.*
*Though I've always wondered about creating a world like this with inhabitants who migrate following the mild(er) border zone between day and night.


For Non-Earthlike Worlds: Other Cycles
Warning: Things will get complicated here if you've piled on the non-Earthlike factors.

The above will be the only factor applying to a planet orbiting a single star in a regular, low-eccentricity orbit, without anything else (e.g. periodic passes of another, large planet between it and the sun) to get in the way.

Most of the following will assume that everything is orbiting on the same plane. Doing otherwise invites nightmarish amounts of calculation.

Eccentric orbits
Eccentric orbits will have a cycle from perihelion (closest to the sun) to aphelion (furthest from the sun).

Multiple Suns
A binary star system will go through a cycle of eclipses, producing two "cool" periods when one star eclipses the other. The precise effects of these cool periods will depend on the two stars involved and which is closest to the planet.

Tidal Heating
Tidal heating is usually constant, but it can be caused/strengthened by a large body passing close by. If your moon/planet has a large neighbour regularly passing close, that's yet another cycle to take into account (one that will effect earthquakes and volcanic activity too).

Moon World Eclipses
A moon world may have its sun regularly eclipsed by its orbited planet, which could interfere with the night/day cycle (if the moon has a fast orbit) or cause periods when the whole moon is in shadow for several days (if the moon has a slower orbit).

To get a picture of your planet's heat cycle, you have to put all of the relevant cycles together.


Fantasy Worlds

Beyond this point I can't be a great deal of help with truly fantastic fantasy worlds, because they're fantasy and they run own their own inscrutable rules. If your rules approximate those for an Earthlike planet (particularly 1-5 and 7) though, you can go through the rest of the process without too much trouble.


Summary:
Find the extremes in your world's heat cycle. For an Earthlike planet this will be a hot summer (when a hemisphere is pointed towards the sun) and a cold winter (when a hemisphere is pointed away from the sun).

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

Working It All Out

Next comes the actual process of mapping everything. Before we get started, you will need:

* An image editing program that can handle layers: I'll be use the GIMP, which is awesome and, more importantly, free.

* A map of your world showing all the land, and the locations of mountains. This doesn't have to be very detailed: even a couple of blobs in about the right shape and position will give you a rough idea of what will be going on. The more accurate your map, the more accurate your climate calculations will be.

* The vital statisitcs of your planet: as many as possible, but most importantly rotation period (day length) and axial inclination.

* The vital statistics of the local star(s). This can easily be fudged to make conditions Earthlike, so only bother if you have definite ideas in that area and/or want to be particualrly hard-science.

* An idea of the key points in your planet's temperature cycle - you will be making a map for each one. For an Earthlike world this will be the summer and winter extremes; other types of world may need to account for other factors

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

Yay!

A minor point: relating to "Multiple Suns", there are only a few stable configurations, all of which are probably worth considering individually in a separate study.

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Two things: firstly, on earth, air doesn't move from colder areas to hotter areas. Secondly, and relatedly, the concept of cells or zones is VITAL to creating a climate.

In outline:
1. Hot air rises on the equator, and spreads out from there
2. The hot air eventually cools, and so falls - in a different place from where it rose
3. The falling air hits the ground and spreads out, in both directions. So yes, some of it goes back toward the tropics, but some of it also goes toward the poles.
4. The air heading toward the poles is warmer than the air it meets, so eventually it rises again
5. The risen air spreads out, again in both directions - some toward the pole, some toward the tropics
6. The air going toward the tropics goes as far as meeting the falling are from stage 2, and falls with it
7. The air going toward the poles cools further and falls again. And so on.
8. This creates 'cells' in the atmosphere of circulating air. Earth has three per hemisphere, but if coriolis forces are greater there may be more (because greater deflection means the air doesn't get as far before it cools/warms)
9. However many cells, there will be an odd number. The tropical (Hadley) cell and the Polar cell are the strong ones, with dominant weather systems, while those in the middle are weaker and have more variable weather.
10. In the middle cell on earth, surface winds flow to the poles, but are deflected by coriolis - so they start by going north, and then turn toward the east.
11. At the 'polar front', these warm southwesterly winds colide with cold northeasterly winds - the result is that they rotate into cyclones, with the mixture of hot and cold air causes fronts of rainfall. The westerly winds are stronger, so these cyclones travel to the east. However, the polar cell dominates over the weaker middle (Ferrel) cell, so the cyclones are often pushed south of their 'natural' habitat around 60 degrees.

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

On this topic, does anybody know how to define the function get_number_of_atmospheric_cells(planetary_radius, rotation_speed)?

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I don't. I think it would be really hard to calculate.

Another interesting question: on earth, the three cells take up about 30 degrees each. Is this necessarily true? Could the middle cell, for instance, be smaller than the two extreme ones?

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

@ Sal: Thanks for preempting the next stage and writing it for me Want to take over?

Where did I say that air moves from hot areas to cold areas on Earth? (I said that they did on Menducia, but that was a fuckup).

@ bricka: I badly need to go back and re-do the Non-Earthlike section of heat cycles with more detail.

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

You didn't say it, I don't think, but you implied it, by pointing out how familiar the basics of climate on Menducia were. Likewise, I didn't say you DID say it... I just implied it.

I'll avoid taking over, if I can, although I may argue with you later on. I've spent a lot of time working on climates and currents and the like.

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

I've gotta say, it's really about time I learned this stuff. I have a very spotty approach to conworlding, such that I don't really have a canonical map, or a name for the planet, but lots of history in places that move around. I need to rework everything, and I may as well start here...

This can only be a good thing.

Also, damn you, you've got me thinking about the atmospheric dynamics of Menducia again.

_________________
"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

I think, based on what has been said here, that my conworlds are effectively semi-soft science with the "laws of physics", such as they are, being defined by a set of ranked statements/paragraphs rather than equations. For example, for whatever reason I like my world's climate to obey a semi-realistic model no matter what the actual internal physics of the world are.

Essentially, I have three rules that come before, and thus override, all internal physics of any con-universes I should care to design:

1. All planets within the habitable zones of their respective stars will have climates approximating the ones they would have in the Real World (even if this makes little sense from the standpoint of the internal physics).
2. All planets within the habitable zones of their respective stars WILL support sentient life; such sentient life will be land-based and bipedal. It does not need to be humanoid, but it is likely.
3. All planets supporting sentient life will have animals, plants, and foods which approximate Earth equivalents to the extent that I can reasonably translate them as the Earth equivalents without being too far off the mark.

I am not so sure about this. We already know that dolphins and porpoises are very intelligent. What makes us certain they are incapable of civilization (right now) is that they are incapable of manipulating their environment to such an extent. Not because of some limitation to their intelligence or anything in the mental department we have that they lack. This so far remains undetermined.

Second, bipedalism is an evolutionary strategy acquired by quadrupedal animals to give them enough freedom to manipulate their environment with their hands. As was just typed, that is the only thing preventing an otherwise intelligent organism from developing their [intelligence] further. You don't need to become bipedal to become an intelligent, civilization-capable species. You only need to manipulate your environment. Chris Wayans' planet Lyr may be a far cry from true science fiction - it seems to resemble more of a fantasy world with furries in it - but he is on the right track. None of those species are bipedal, but many of them are capable of creating a civilization.

Third, I think you are confusing "sentience" with "sapience." Sentience basically means the organism is aware of itself. Sapience is a much more new term and I am not even sure if it is officially recognized. It means a species that has, or is capable of producing, a complex social and material culture. It comes from the Latin word for "wise" so it makes sense.

And finally, please don't fall into the convergent evolution trap. Yes, convergent evolutiondoes happen to some degree, but having a counterpart for every Earth organism in speculative or science fiction is just an excuse for lack of imagination and knowledge of the extent of evolutionary processes.

he didn't say that's how the real world behaves, but how he likes his conworlds.

That depends on what you want your conworld for. If you're writing a book and want to concentrate your efforts on the story rather than on reworking the entire evolutionary tree just to give the more pernickerty and meretricious readers con-orgasms over your world-building, I really can't see any harm in keeping things Earthlike.

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Hey, guys, the Church of Exobiology is across the street.

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"It is quite certain, in particular, that I have always been insane." ~ Aleister Crowley

"Save us all from arrogant men/And all the causes they're for/I won't be righteous again/I'm not that sure any more." ~ Shades of Grey, Billy Joel

My foci in conworlding are climate, culture, and language, not biology. I'm more interested in seeing what sort of human cultures might develop given different landforms and climatic parameters than what exist on Earth. To do that, my species need to be humanoid. I specifically use the convergent evolution "trap" as an excuse for lack of imagination and knowledge of the extent of evolutionary processes, because I don't care about them. That's not my goal here.

Besides which, the Three Rules I listed override ALL other laws of physics in my conworlds, including those of logic and causality. It doesn't matter that it doesn't make sense for it to do so, because the part where things have to make sense is ranked beneath it.

However, valid point about sentience versus sapience. And yes, we probably should get back to climatology.

Here's the address.

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