40% is a rather selective reading of that article. The article you link states:

"Now, the International Energy Agency has weighed in with a report on integrating renewables. It finds that, as long as intermittent power sources are under 10 percent of the total energy use, they can essentially be added for free."

That's pretty close to what I just said. (The article is talking about wind plus solar, while I was discussing solar alone). It goes on to talk about higher penetration:

"The report lumps wind and solar into a category it terms "variable renewable energy" and then it says "Things start to change as the fraction of power generated by VREs approaches 20 percent, and there are definitely new challenges as it reaches 30 to 40 percent."

So: I said solar is excellent at market penetration up to 10%, and this article says for solar plus wind together the cost changes at power fraction up to 20%, with "new challenges" as it reaches 30 to 40%.

I'd say we're saying the same thing.

As for the 40% you quote, the article says "that would require substantial reshaping of the rest of the grid--something that's much easier to do outside of mature economies."

The U.S is a mature economy, so that part isn't talking about us.

A "watt", for solar, means one watt of electrical production at noon on a cloud free day.

Since peak power usage (in the US) tends to be in the afternoon, that's excellent up to about 10% market penetration Above that, you need energy storage, which is currently not cost effective, although there are several systems that are coming along in the future and look good. However, storage adds to the cost-- it's no longer a dollar a watt if you have to operate and pay for a storage system.

Solar is also less effective in winter (shorter days) and in locations with significant overcast.

Solar is great-- for some utility applications. The true answer is, there is room for multiple approaches to technology development.

That's misleading. Social Security is paid for with Social Security withholding-- it actually pays more into the budget than it pays out.

Likewise, Medicare is paid for by a separate fund, which goes into the medicaid trust fund..

Right. Alice can differentiate between Bob reading the message and a Man in the Middle interception, because to intercept the message, the man in the middle has to read the quantum bit -- that is, in the photon case, measure the polarization-- and reading it destroys it. The Man in the Middle can't then send on a copy of the quantum bit, because of the quantum no-cloning theorem. She can send a photon polarized in a way identical to the way she read the photon-- but that only works if the receiver, Bob, happens to choose the same polarization to measure that the Man in the Middle chose to measure.

There is, however, a footnote to this. Eve actually can clone the photon (cloning photons is what a laser does). But she can't clone it perfectly-- or, more specifically, she can't be sure that the "cloned" photon is actually a copy of the original, or a spurious ("spontaneous emission") photon that happens to be in the same place. So, if she clones the photon, and measures one copy, and sends the other copy on, this shows up as noise in the signal-- exactly the same as stray light. So, Eve can read some of the message, if she's sufficiently clever, but how much is limited by how much noise the people communicating will accept in the signal without realizing that they are tapped.

The obligatory xkcd

Both.

From Wikipedia https://en.wikipedia.org/wiki/Brian_Cox_%28physicist%29: "In the 1980s he was keyboard player with the rock band Dare [ref: http://women.timesonline.co.uk... newspaper= The Times 24 February 2008]

Apparently something about naming English blokes "Brian".

Sigh.

In the absence of an atmosphere, the temperature of a planet would be follow the Stefan-Boltzmann equilibrium law, P absorbed = P radiated, or alpha Io (pi R^2)= epsilon sigma T^4 (4 pi R^2)

where Io is the incident intensity, alpha and epsilon the absorptivity in the solar spectrum and emissivity in the thermal spectrum, R the planet's radius, T the temperature (absolute), and sigma the Stefan-Boltzman constant.

Even if Venus weren't extraordinarily reflective--highest albedo of all the planets-- the surface temperature in the absence of an atmosphere would only be higher than Earth's average by the fourth root of the intensity, which is the square root of 1/distance, which is a factor of 1.179. That calculates out to about 50C above Earth's average temperature. It is actually somewhat over 400C higher in surface temperature than Earth.

Yes, it's closer to the sun. No, that isn't a sufficient explanation for why it's so much hotter than Earth.

I've been waiting years for a good explanation of Higgs!
Too bad. Still waiting.

When you state "The atmosphere is incredibly dense... and retains the heat fairly efficiency"--that is a description of the greenhouse effect. The fact that you don't actually understand how the greenhouse effect works doesn't affect the fact that when you state that a dense atmosphere retains heat, what you're describing is known as the greenhouse effect.

I'm sorry, but we seem to have reached the point where you call me ignorant and I point out that you are ignorant. Unfortunately, you seem to be know so little about atmospheres that the conversation really isn't going anywhere. Ignorance is curable, though, so perhaps sometime in the future you'll be capable of an interesting conversation. I assume you're in high school? Well, keep at it, learn something, and in the future, you'll be able to contribute.

Have a good one. Bye.

Wow-- so you're proposing that the volcanoes supply heat, and then the atmospheric greenhouse effect traps the heat and keeps it warm.

Greenhouse effect and volcanoes!

I've got to give you credit for creativity. Why don't you do some calculations and write a paper for the AGU?

From the evidence, apparently not.

In the next comment down, Eunuchswear said "Venus isn't hot because of the greenhouse effect, it's hot because of the enormous pressures caused by an incredibly dense atmosphere."

So, why don't you and Eunuchswear get together and get your stories straight. Do some calculations, maybe. Figure out which one it is you're claiming: the pressure? Or the volcanoes?

No, actually, I don't.

I want people to understand the science. I want people to understand that there is science here; that the greenhouse effect has been known and studied for a long time, it is relatively well understood, and the models are well tested. I want people to stop attacking the science when they don't like the political consequences that they believe would ensue if they believed it. The argument "it would be extremely expensive if the science were correct so therefore the science must be wrong" is not a logical argument. This is worth emphasizing: the correctness of the science is independent of your beliefs about the consequences.

As for the question "what should we do about it-- well, that is worth discussing. Maybe nothing. But, as far as I can tell, whenever anybody suggests any discussion, a small group of people start shouting "Stop discussing this! The science is a hoax! It's not real! It's a scam!"

Me personally? I live in Ohio-- a bit of global warming would be nice, I'm in favor of it. Global warming will both have benefits and cause problems, of course. I find it amusing to notice that the three countries that have been most adamant in blocking global warming discussions are Canada, Russia, and Norway-- obviously, they've done the same calculation.)

Yes. In fact, because the atmosphere of Venus is so opaque in the thermal infrared, it is easy to analyze-- it's one of the few planets that can be analyzed with a relatively simple back-of-the-envelope calculation.

If you don't understand that the temperature of surface of Venus is due to the greenhouse effect, you don't understand the greenhouse effect. It's not actually a crime to not understand something-- the greenhouse effect is poorly explained in popular culture, and few people have even a clue how to do a calculation, even a simple one-- but when you don't understand something, that might suggest that you should learn, rather than shoot off uneducated opinions.

No. Take a look at the solar spectrum some time. Almost all of the energy of incident sunlight is in a spectrum range in the visible and near IR-- peaking around one micron. The energy of the exiting infrared is in much longer infrared-- ten to twenty microns. (The fact that it's longer wavelength is Wien's law). You can have an atmosphere transparent to incident light, but absorbing to exiting infrared. This was discovered in the late 1700s.

I'm sorry, but at this point you are revealing that you don't actually understand what you're talking about, so bye, have a nice life.

The lifetime of water emitted into the air is so short that no, you really don't get a long-lasting greenhouse effect by directly emitting water. It condenses out. We call this "rain" on our planet.

It is, however, an amplifying effect: if you make the average temperature a little bit warmer for some other reason, that means that more water evaporates and the atmosphere can hold more water, which raises the temperature. This increases the effect of other greenhouse gasses, such as CO2.

If you ever get to the point where the amplification factor is greater than 1 (that is, 1 increase in temperature increases the atmospheric water such that it increases the temperature by another 1), you get "runaway greenhouse effect." Fortunately, Earth is far away from this condition. (It is believed to have happened on Venus, though.)