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[Dozebôm Lolumzalìs]

"But we can't actually measure any of those constants! They could be anything!" I kid you not. What do you even say to this guy? (I'm guessing a recital of 4'33", followed by retreating footsteps. Or the other way around.)

[TheDarkStar]

How to measure albedo:

Measure the Sun's luminosity

Measure the size of the desired planet

Calculate how much light hits that planet

Wait until the planet's sun-facing side is visible

Measure the amount of light reflected from the planet to us

Calculate the fraction of the reflected light that is directed towards us and the theoretical intensity of that light if all of it were reflected

Divide the measured amount of light by the theoretical amount

[Dozebôm Lolumzalìs]

Ah, that seems painfully obvious. What about the other two?

Wait - what about the radiation from the planet itself? Wouldn't that mess up your equations?

[Frumple]

... I'm pretty sure that if Venus is emitting enough light to substantially influence this stuff we've got considerably bigger issues than an equation that's slightly inaccurate.

[Dozebôm Lolumzalìs]

But it HAS to be emitting as much as it receives (and doesn't reflect). Otherwise, it wouldn't be in thermodynamic equilibrium.

[MetalSlimeHunt]

Alas, much like with the entropic principle's application to evolutionary biology, we are undone. Your friend's clever machinations have exposed our beliefs as a mindless liberal hive mind intent on the dogmatic enslavement of all humanity, as neither evolution or climate change can possibly be true in the face of thermodynamics.

Yes, for any of it to be true there would have to be an obscene source of constant power bearing down on all the planetary bodies of our solar system, filling them with potentiality against the void.

Now you both must die, for you have learned too much.

[Loud Whispers]

I saw nothing

[Max™]

Yes, for any of it to be true there would have to be an obscene source of constant power bearing down on all the planetary bodies of our solar system, filling them with potentiality against the void.

^That is hilarious, since a key part of the greenhouse effect is the assumption that the skyfire isn't sufficient to explain temperatures by itself, though that is mostly a problem when you work out the average energy received by a planet and calculate the expected temperature rather than looking at the temperatures expected due to say, the instantaneous power integrated across the surface.

Edit: Is there any way to explain Venus's temperature without the GH effect?

Volcanic overturning events of the crust are the only way to explain the uniformly young surface given the lack of plate tectonics. These events would involve injections of heat and gas in massive amounts but without processes which remove CO2/SO2 from the atmosphere it wound up with an excess for a terrestrial planet. Roughly 90 times the atmosphere means roughly 90 times the pressure, there is no way to have that much atmosphere without it being extremely hot at the bottom, this is just what a column of gas suspended in a gravity well does. This is obvious for the atmosphere of Jupiter, Saturn, Uranus, Neptune, but for Venus the mere suggestion is absurd.

I remember being mocked the first time I suggested that idea, but it seems obvious due to how I'm looking at it. Take a long and thin cylinder of air floating in space away from a gravity well, the gas will equilibrate with the temperature of the walls, distributed evenly inside, right?

Now have an engine oriented along the long axis, with the "floor" nearest, and the "ceiling" furthest from it.

Start accelerating the tube, observe what happens. Does the gas remain evenly distributed, or does a pressure gradient develop at one end? If the volume remains constant but there is a pressure increase at one end, what happens to the temperature? What is the point? Gravity is accelerating gas suspended above the surface of a rotating rocky planet, in the absence of an input the gas will cool and settle down until it freezes, otherwise it will tend towards a state with the average temperature found at some point above the surface, the warmest temperatures at the surface below the input, coolest would be where the most indirect energy is received near the rotational poles on the night side.

Also worth noting that the air lifted to higher altitudes on the sunward side winds up descending on the nightside, gaining kinetic energy as it does so. The extremely slow rotation rate and atmospheric superrotation plus the massive scale height makes this a possibly significant energy input which is unaccounted for. There isn't enough time or gas here for it to matter, but on Venus it lends support to the idea that the equilibrium surface temperature is set by the cloud reflectivity ~50 to 60 km up, as the system can't relax and cool faster than the input/output at that altitude allows, making a literal pressure cooker, if you will.

_______________________________________

In other news, we have been picturing sabertooth tigers wrong in a really obvious way once you see the reasoning: http://antediluviansalad.blogspot.com/2016/05/your-puny-lipped-sabertooth-kitty-is.html

front/closed, side/closed, side/slightly open

side/yawn~bite, side/flehmen

Sabertooths don't have sexual display tusks (which have very low enamel content in all but young animals) they have killing tools which have to be kept sharp. Exposing them to air means they aren't bathed in saliva and lose calcium, get abraded by grit, are vulnlerable to being kicked, and so forth.

Sabertooths also have great big foraminae in their upper jaw which don't make sense if they're only feeding a normal sized patch of whiskers. Whiskers which wouldn't be close to the bite target unless the upper lip was a lot larger anyways.

Cats aren't able to see what they bite, they use whiskers to aim their killing bites more precisely, of course a sabertooth would do the same.

[alway]

But it HAS to be emitting as much as it receives (and doesn't reflect). Otherwise, it wouldn't be in thermodynamic equilibrium.

Yep; and it's also very distinguishable which is which -- and ties into various other facts. See, glowing isn't a uniform thing; and this fact is a big part of what inspired quantum mechanics and shed light on how chemistry works. Every atom has a number of electrons, which exist in *discrete* orbits. When they hop from orbit to orbit, in particular upon falling back down to a lower orbit, they emit light, and absorb light as they hop up. Additionally, more energetic falls mean more energetic photons. So by observing the wavelengths, you can determine how much energy is being emitted/absorbed as well as what materials emitted/absorbed it. Which is also how we know the composition of stars to a high degree of accuracy. So from there, you can figure out the composition of Venus' atmosphere as well as what its emissions look like (just a bunch of low energy infrared stuff mostly), and figure out what's reflected and what's emitted.

In fact, here's what looks to be a lecture on the topic with lots of diagrams: http://lasp.colorado.edu/~bagenal/3720/CLASS5/5Spectroscopy.html
"The spectrum of all planetary objects (and humans, for that matter) has a double hump - a one in the visible region due to reflected sunlight and another in the infrared due to thermal emission of the planet."

The most fascinating part of the diagrams isn't just the fact that they show something, but most of them show something so completely unambiguously as to be indisputable even by a layperson like me.

[Reelya]

Scientists have discovered that horses can learn to use another human tool for communicating: pointing to symbols. They join a short list of other species, including some primates, dolphins, and pigeons, with this talent. Scientists taught 23 riding horses of various breeds to look at a display board with three icons, representing wearing or not wearing a blanket. Horses could choose between a "no change" symbol or symbols for "blanket on" or "blanket off." The horses did not touch the symbols randomly, but made their choices based on the weather. If it was wet, cold, and windy, they touched the blanket-on icon; horses that were already wearing a blanket nosed the "no change" image. But when the weather was sunny, the animals touched the blanket-off symbol; those that weren't blanketed pressed the "no change" icon. The study's strong results show that the horses understood the consequences of their choices, say the scientists, who hope that other researchers will use their method to ask horses more questions. The report has been published in Applied Animal Behaviour Science.

[Putnam]

...I don't see much how their actions there differ from standard operant conditioning.

[Reelya]

It's not really like Skinner's operant conditioning at all. Also the point was that they're using symbols to represent the decision. Which only half a dozen species can do.

So they're making a binary assessment of "needs-blanket", vs "doesn't-need-blanket" based on all the variables that go into "the weather", which shows ability to abstract complex data. They're then cross-referencing that against the "blanket/not-blanket" binary variable. And from that they can identify three different possible choices based on the situation. At the simplest, they're making a binary choice, but what they're choosing between is dependent on the outcome of a different binary variable. That's the clever thing: the "no change" symbol can be chosen whether or not they have a blanket, and whether or not it's hot or cold outside - all three choices are context-sensitive. The decision to pick that symbol is dependent on both variables. So it's a fairly advanced decision making process, involving abstracting the concept of "weather" down to a binary, and understanding an independent state variable, and how symbols can mean different things in a context-sensitive way. Not to mention that after making this assessment they are actually reading the choices as symbols then picking one.

[scrdest]

In other news, we have been picturing sabertooth tigers wrong in a really obvious way once you see the reasoning: http://antediluviansalad.blogspot.com/2016/05/your-puny-lipped-sabertooth-kitty-is.html

Sabertooths don't have sexual display tusks (which have very low enamel content in all but young animals) they have killing tools which have to be kept sharp. Exposing them to air means they aren't bathed in saliva and lose calcium, get abraded by grit, are vulnlerable to being kicked, and so forth.

Sabertooths also have great big foraminae in their upper jaw which don't make sense if they're only feeding a normal sized patch of whiskers. Whiskers which wouldn't be close to the bite target unless the upper lip was a lot larger anyways.

Cats aren't able to see what they bite, they use whiskers to aim their killing bites more precisely, of course a sabertooth would do the same.

This is actually kinda really cool. It looks like someone crossed a regular cat with a snek.

[Reelya]

That sometimes happens with science, some common-sense or "obvious" explanation for something gets the treatment "pfft! all 'scientific' people know that <situation X> is because of <unlikely scenario with some vague shred of evidence> not because of <what people have always assumed>". And then the believers in the new-fangled theory get almost religiously arrogant about it. One example I saw was in the 90s on TV, some diet people were talking about and old wives tale that if your kid has a taste for carbs, he'll get fat. All the "experts" soundly laughed, because carbs are "low fat" therefore they couldn't "make you fat".

Generally, sexual display characteristics don't involve completely deforming a critical system that you need for eating.

I've seen a number of times when the "old wives tale" version was laughed out of the "scientific" room, only for that explanation to later become accepted again. The most recent one is the "cold doesn't give you a cold" theory. Sure, that sounds good because we can cite complex factors that play a role, and laugh at the dumb old people who believe otherwise. Except now they're finding scientific evidence that the exact temperature in your nose plays a vital role in the rate at which cold viruses actually spread. It's a combination of the virus prefering cold, wet conditions, and the nose's immune system operating below peak performance at lower temperatures. People laugh at Japanese people for believing the "keep warm" thing in anime, and we scoff that their paper masks aren't really effective to keep viruses out. But wearing one of those paper masks would definitely give you a 3-degree boost in nasal temeperature, taking you out of the danger zone. Part of the problem is taking a partial theory then over-extending it. We know that cold itself doesn't "give" you a cold, therefore "sciency" people have leapt to the conclusion that those "keep warm" people are talking out their asses. When in fact, it's still an effective measure to reduce colds.

[Putnam]

can we all agree on fan death though