PV Gap

Carole Said:

So what's all this about sunspots then? How do they affect the Suns influence on our climate?

We Answered:

Actually, that .1% variation is just variation in visible light (TSI). Here's a link discussing the flaw with using TSI to dismiss the sun's role in climate change:

http://www.lowell.edu/blog/?p=89

"In an opening keynote talk, Judith Lean of NRL reviewed the status of solar irradiance variability models relative to the latest observations of the total solar irradiance (TSI) as measured by SORCE. Judith made a number of points, but to my mind, here’s the central one. Our understanding of the role of solar variations in climate change is based largely upon observations of the Sun’s total brightness variability. As those of you who follow these things know, the 0.1% variation in solar brightness over the course of its activity cycle does not impart sufficient radiative forcing to account for climate change since about the mid 20th century; another, presumably anthropogenic, signal must be present. Here’s the critical twist: the spectral distribution of the Sun’s cyclic variability is quite different depending on where you look in the spectrum. In particular, the ultraviolet variability is much, much larger than the total variability — a few tens of percent — and the UV radiation significantly affects the stratosphere, in ways that are poorly understood. The next avenue for real progress in Sun-climate relationships lies in breaking down the total irradiance variation into its spectral components, and beginning to understand what effects they have on climate. We are just now starting to assemble the observations, which must be done from space, to address this issue."

Evidence solar UV radiation variability and coronal holes are affecting Earth's atmosphere found here:

http://www.sciencedaily.com/releases/200…

"While extreme ultraviolet radiation from the sun is the dominant mechanism that causes the thermosphere to "breathe," the new CU-Boulder study indicates high-speed wind from the sun triggers independent breathing episodes by creating geomagnetic disturbances, heating the thermosphere and altering its density. The wind streams are generated by relatively cool pockets on the sun's surface known as solar coronal holes that periodically rotate around the sun's surface, said Thayer.

"We were surprised to find the density changes were so consistent in our observations," said Thayer, lead study author. "Because of the huge increase in satellite activity in recent years, finding this new thermosphere breathing mechanism should help improve our models and increase the accuracy satellite tracking and collision avoidance.""


We are currently at a solar minimum between solar cycles 23 and 24...one of the quietest seen in several cycles. Just as you were taught about the 'Maunder Minimum', we are currently living in 'The Modern Maximum': The most active period of solar activity seen in over a thousand years. The current silence from ol' Sol suggest this period of extreme solar activity may be waning. If so, expect cooler than average temps to prevail over the next few decades.

"Claus finds that right now, near the dead minimum between solar cycle 23 and 24, the Sun is fainter than it was between the 1996 minimum of cycles 22 and 23. This is hugely important, since identifying changes in the solar brightness at minimum, when the Sun is mostly or entirely free of “active” features like sunspots, is perhaps the critical observation for determining whether the Sun is growing steadily brighter or fainter on the long term. Even more interesting, my preliminary analysis of my 2007 spectroscopic observations of the Sun show the same thing…it looks like the current minimum is lower than the last one." -same link as first

Suzanne Said:

Book of Eli questions *** SPOILER ALERT ***?

We Answered:

Question #1: People were looking at Eli's hands to see if they were shaky. The old couple in the farmhouse had shaky hands, and Eli explained to Solara that the shakes come from eating human flesh.

Question #2: The script does not mention the cause of the war. However, religion is often blamed for conflict; or used cynically by those who would gain power through its misuse-as was Carnegie's plan.

Question #3: The "Big Flash" is also not explained. Coupled with the war, I would assume that it was a massive thermonuclear attack which destroyed the ozone layer; but your friend is correct in thinking that a large solar flare would have much the same effect.
Ultimately, the exact identity of the flash is irrelevant to the plot, and I agree with the writer's decision to not explain it. The plot is better advanced by focusing on the journey, not the cause.

Miriam Said:

my Friend wrote this really nice thing about me on her bebo.bt i want 2 write sumfin about er bt i dnt no wat?

We Answered:

I think what you just wrote was great, why not use that?

Sean Said:

Other than Dark Matter, what else could make up the missing mass of galaxies?

We Answered:

Hmmm number 4, could it shed some light on this? Is that not the whole point of the LHC, to detect the theoretical remnants of the Higgs Boson particle thus proving or disproving the overly messy standard model?

Rick Said:

Significant digits/figures question?

We Answered:

I think you have analyzed the question correctly.
The 3 answers would be:
145161979200000000
1.451619792 x 10^17
1.5 x 10^17

Actually, this final answer has 2 significant digits, but the concept of significant digits is a little "squishy." With the 2 significant digits here (1.5), we are saying that we know the value is between 1.45 and 1.55. That is, we know it with an accuracy of plus or minus 0.05 out of 1.5, i.e., the possible error is 0.05 / 1.5 = 3.3%.

However, the possible percentage error in our original data point (4.6) was only 0.05 / 4.6 = 1.1%. So we are understating the degree of accuracy by using only 2 significant digits in our answer. In other words, 2 significant digits of accuracy are considerably more accurate when the first digit is 4 than when it is 1 (and is greatest when the first digit is 9).

Bottom line: The number of significant digits is a measure of the potential percentage error in a value, but it is only a ROUGH measure of the percentage error.

Albert Said:

How many miles per dollar(mpd) do hydrogen cars get as of now?

We Answered:

Anywhere from 2 to 90 miles per dollar: The cost of hydrogen fuel is rather difficult to find. Here is an article that says hydrogen costs "$1 to $20 a kilo. A gallon of gasoline has the same energy content as a kilo of hydrogen, but vehicles using the latter get two to three times higher mileage."1 First some fact checking. Here is a chart that tells equivalencies and confirms that a kilo of hydrogen equals about the same BTU as a gallon of gasoline.2 While a hydrogen fuel cell electric car will get this kind of increase in mileage an internal combustion engine running on hydrogen probably will not.

We can assume that an average car will get 20 to 30 miles per gallon and so a hydrogen car ( a fuel cell electric vehicle) will get 2 to three times this or 40 to 90 miles per kilo of hydrogen.

At $1.00 per kilo hydrogen is going to give you a minimum of 40 miles and a max of 90 miles. This will cost you from ($1.00/40 to $1.00/90) $.025 to $.011 per mile at the low price. (40 to 90 miles per dollar)

At the high price of $20 this would be ($20/40 to $20/90) $.50 to $.22 dollars per mile (2 to 4.5 miles per dollar.)

The price of the vehicle seems to be from a low of about $100,000 to about $1,500,000. There is no way to know how heavily the price of the vehicle, the fueling station or the fuel is subsidized.

The cost of adding hydrogen fueling stations seems to run about $50,000 while a fast charging station might be 1/10 the price and a natural gas fueling station might be 1/5th the price. Hydrogen is going to be made primarily from gas reforming as it is today and is the reason petrochemical companies are very interested. Then like an EV the vehicle may be operated cleanly but the infrastructure would be in doubt. The difference is that it is less likely that hydrogen would be acquired cleanly and certainly with less efficiency than simply powering a natural gas car or an electric car directly.4