Before jumping to too many conclusions about the ozone hole over Antarctica, we should remember it was first observed in 1958 -- a time when CFC use was just beginning. In those days, there was interest in the upper atmosphere and considerable research efforts because of its importance to HF radio communications.
The British Antarctic Survey group that made the observations was expecting to find an ozone hole because of the predictions of their atmospheric model. In 1958, UV spectrometers used vacuum tubes, were big and heavy and carting them to the Antarctic was quite an undertaking. They had good reasons to expect a positive result.
I am not an atmospheric physicist so the following might be a little naive. However, here is my understanding of their theory:
1) Ozone is made primarily at low latitudes
where vacuum UV has direct access to
the upper atmosphere. Little vacuum UV
reaches the atmosphere at high latitudes
because it has already been absorbed by
low-latitude air.
2) Ozone reaches high latitude locations
by the natural convection processes in
the atmosphere. If the earth did not
spin, air would rise at the equator
and fall at the poles, transferring
the ozone there from the equator.
3) The rotation introduces Coriolis
force and deflects the movement to
the "trade wind" pattern we know. It
also produces a phenomenon called the
South Atlantic Vortex -- an air-flow
pattern that greatly reduces
interchange of air from the equator
to Antarctica.
4) With little air interchange, there
should be little ozone over Antarctica.
There is now so much spin surrounding CFCs and Ozone Holes we will probably never learn whether or not their theories were correct. It is not something any atmospheric scientist can afford to challenge and still get his next research grant.
As a final thought consider the business aspects of CFC use. When you go business school, one of the first things you are taught is, "never let your product become generic." When your patents are about to expire, you must find a way of making your old product obsolete and replace it with a new one. Otherwise, generic manufactures will duplicate it for a lower price.
Drug companies frequently keep a few safety studies up their sleeves for this purpose. Of cause, they have a new version of the drug, with some minor changes to an inactive part of the molecule, which fixes the problem.
When NASA rediscovered the Antarctic ozone hole, in the 80s, it was really good news to CFC manufacturers who were facing their own "generic problem." We will never know if their public relations departments helped along the CFC scare but...
Until fairly recently, laser efficiency was very poor -- sub 10%. Recent solid state lasers are better -- I have read reports as high as 40%.
However, if you are running the laser from a heat engine powering an electrical generator, you will still end up dissipating locally several times the power in the beam.
Then, the beam will diverge because of diffraction, atmospheric turbulance and, perhaps, non-linear optical effects of the atmosphere. There will also be absorption due to clouds, polution, smoke, etc.
I expect it will be a significant engineering challenge to deploy a weapons laser, as described in the article, that blows a bigger hole in the enemy vehicle than it does in your own.
My wife and I are British, but lived in Boston, Mass for a few years during the mid eighties. We live in Canada, these days.
When we first arrived there, we thought the news reporting was very narrow so we purchased an HF radio, to listen to the BBC World Service. In those days, the BBC operated a very good news service. It has been reigned in a lot since -- they made the mistake of annoying Margaret Thatcher.
One evening, we heard a report on the BBC about a Bankers conference on the US West Coast. The report contained excepts from a talk given by the (then) chairman of the FDIC and contained pretty strong material. Essentially, he claimed that US banks had over extended themselves with too many bad loans for the FDIC to be able to salvage the situation.
I thought this news would be a major talking point the following day; it wasn't -- no one had heard it. As far as I could tell, in discussions with my co-workers, this news was not available on any outlets generally available to people in Boston. Several of my US friends from that time then went out and bought HF radios.
To this day, I don't know why the FDIC chairman's speech was not reported in the Boston area. Maybe the editors thought the Red Sox were more important than a major bank failure. Perhaps they simply dismissed it as "West Coast" news and therefore unimportant. Maybe the TV stations and local papers did not want to spook the advertisers -- who knows? In any event, the experience was an education.
I used to dabble in Amateur Radio, mainly 2 meter packet. In those days, about 8 years ago, there were a number of digital HF schemes. About the best of them was Clover -- an AT-compatible board that used its own modulation scheme and protocols.
One problem with HF is that the ionosphere has a large, time-dependant phase dispersion. It really procludes wide-band schemes unless someone can come up with something very clever.
The Clover board claimed 500 characters per second, under good band conditions, through a 25 Hz cw filter. At the time, there was no HF scheme that came close.
I have no idea if Clover still exists -- maybe someone on Slashdot can enlighten us.
77,000 tons sounds like a lot but, at least, it is a sufficiently small quantity to be stored. It is a drob in the ocean compared with the quantity of waste produced by chemical power plants where the only practical option is to dump most of it up the smoke stack, into the atmosphere.
Generating energy is a dangerous buisness with ANY currrent technology. In terms of Jules per corpse, the safety of nuclear power is pretty competative. I don't want to live near any power plant but, given the choice, I would rather live near a nuclear plant than twenty miles down wind of a coal or oil-burning power station.
A great deal of debate goes into risks from various energy production and distribution technologies. For some reason, beyond me, nuclear power seems to take the most flak.
Now, ALL energy technologies kill people. Windmills break blades and cause injury, hydroelectric dams burst, people fall from roofs cleaning snow from solar cells or they die from the pollution from fossil fuel or nuclear power generation.
Technologies we perceive as safe, like solar cells, also produce very little energy -- particularly when we account for the energy required to manufacture and deploy them. Therefore, we need a safety figure-of-merit that normalizes the risk with the energy produced.
Let me propose using the following:
Joules/Corpse
I expect, on this basis, the wood stove would come out about the worst and nuclear energy the best. It would also be fun watching spin groups around the world working to skew the figures.
The ozone hole was discovered back in 1958 by the British Antarctic Survey. At the time, they saw it as a natural phenomenon caused by the South Atlantic Vortex -- a well established air movement pattern.
Now, there may be some real science behind CFCs and ozone depletion. The original lab work that demonstrated the chemistry was real. However, most of the material that comes my way about CFCs in the atmosphere seems more like spin than science. Maybe someone here can point us to some more measured and competent publications than I have been able to find.
Before we jump to too many conclusions about all the anti-CFC material, we should bear in mind it is standard practice for corporations to seek methods for making obsolete materials for which the patents have expired. Some creative lobbying and legislation is a great way to stop third-world companies turning out your products on the cheap.
It is a little like saying to someone from Montreal, "Your from Canada... You must know my aunt Mary in Vancouver."
Seriously, I visited a display on the SNO at the Sudbury Science Center. I was particularly taken by a specimine of the photomultiplyer tube they were using. It was a good meter in diameter and must have weighed 500kg. From memory, there are several thousand of them in the SNO.
If you are ever in Sudbury, the Science Center is well worth a visit. It one of the few science museums I have seen with a real sensitivity for science and scientific method.
I wonder if spinning mercury mirrors could form a good basis for searching for earth-orbit crossing asteroids. It would mean building a telescope at every few degrees of latitude and using the Earth's rotation for scanning.
The price of the optics could be right but the data-management task would be huge. It would also mean finding countries where the military would not get too bent-out-of-shape with people doing whole-sky scans -- I expect that rules out the USA.
I have seen fairly small mercury mirror systems (aperture of about 1 meter) and the technology is within the range of gifted hobbyists. Perhaps volunteer groups around the world could make such a system with some expert help.
Slashdot Mirror
Before jumping to too many conclusions about the ozone hole over Antarctica, we should remember it was first observed in 1958 -- a time when CFC use was just beginning. In those days, there was interest in the upper atmosphere and considerable research efforts because of its importance to HF radio communications.
The British Antarctic Survey group that made the observations was expecting to find an ozone hole because of the predictions of their atmospheric model. In 1958, UV spectrometers used vacuum tubes, were big and heavy and carting them to the Antarctic was quite an undertaking. They had good reasons to expect a positive result.
I am not an atmospheric physicist so the following might be a little naive. However, here is my understanding of their theory:
1) Ozone is made primarily at low latitudes
where vacuum UV has direct access to
the upper atmosphere. Little vacuum UV
reaches the atmosphere at high latitudes
because it has already been absorbed by
low-latitude air.
2) Ozone reaches high latitude locations
by the natural convection processes in
the atmosphere. If the earth did not
spin, air would rise at the equator
and fall at the poles, transferring
the ozone there from the equator.
3) The rotation introduces Coriolis
force and deflects the movement to
the "trade wind" pattern we know. It
also produces a phenomenon called the
South Atlantic Vortex -- an air-flow
pattern that greatly reduces
interchange of air from the equator
to Antarctica.
4) With little air interchange, there
should be little ozone over Antarctica.
There is now so much spin surrounding CFCs and Ozone Holes we will probably never learn whether or not their theories were correct. It is not something any atmospheric scientist can afford to challenge and still get his next research grant.
As a final thought consider the business aspects of CFC use. When you go business school, one of the first things you are taught is, "never let your product become generic." When your patents are about to expire, you must find a way of making your old product obsolete and replace it with a new one. Otherwise, generic manufactures will duplicate it for a lower price.
Drug companies frequently keep a few safety studies up their sleeves for this purpose. Of cause, they have a new version of the drug, with some minor changes to an inactive part of the molecule, which fixes the problem.
When NASA rediscovered the Antarctic ozone hole, in the 80s, it was really good news to CFC manufacturers who were facing their own "generic problem." We will never know if their public relations departments helped along the CFC scare but...
Until fairly recently, laser efficiency was very poor -- sub 10%. Recent solid state lasers are better -- I have read reports as high as 40%.
However, if you are running the laser from a heat engine powering an electrical generator, you will still end up dissipating locally several times the power in the beam.
Then, the beam will diverge because of diffraction, atmospheric turbulance and, perhaps, non-linear optical effects of the atmosphere. There will also be absorption due to clouds, polution, smoke, etc.
I expect it will be a significant engineering challenge to deploy a weapons laser, as described in the article, that blows a bigger hole in the enemy vehicle than it does in your own.
My wife and I are British, but lived in Boston, Mass for a few years during the mid eighties. We live in Canada, these days.
When we first arrived there, we thought the news reporting was very narrow so we purchased an HF radio, to listen to the BBC World Service. In those days, the BBC operated a very good news service. It has been reigned in a lot since -- they made the mistake of annoying Margaret Thatcher.
One evening, we heard a report on the BBC about a Bankers conference on the US West Coast. The report contained excepts from a talk given by the (then) chairman of the FDIC and contained pretty strong material. Essentially, he claimed that US banks had over extended themselves with too many bad loans for the FDIC to be able to salvage the situation.
I thought this news would be a major talking point the following day; it wasn't -- no one had heard it. As far as I could tell, in discussions with my co-workers, this news was not available on any outlets generally available to people in Boston. Several of my US friends from that time then went out and bought HF radios.
To this day, I don't know why the FDIC chairman's speech was not reported in the Boston area. Maybe the editors thought the Red Sox were more important than a major bank failure. Perhaps they simply dismissed it as "West Coast" news and therefore unimportant. Maybe the TV stations and local papers did not want to spook the advertisers -- who knows? In any event, the experience was an education.
I used to dabble in Amateur Radio, mainly 2 meter packet. In those days, about 8 years ago, there were a number of digital HF schemes. About the best of them was Clover -- an AT-compatible board that used its own modulation scheme and protocols.
One problem with HF is that the ionosphere has a large, time-dependant phase dispersion. It really procludes wide-band schemes unless someone can come up with something very clever.
The Clover board claimed 500 characters per second, under good band conditions, through a 25 Hz cw filter. At the time, there was no HF scheme that came close.
I have no idea if Clover still exists -- maybe someone on Slashdot can enlighten us.
77,000 tons sounds like a lot but, at least, it is a sufficiently small quantity to be stored. It is a drob in the ocean compared with the quantity of waste produced by chemical power plants where the only practical option is to dump most of it up the smoke stack, into the atmosphere.
Generating energy is a dangerous buisness with ANY currrent technology. In terms of Jules per corpse, the safety of nuclear power is pretty competative. I don't want to live near any power plant but, given the choice, I would rather live near a nuclear plant than twenty miles down wind of a coal or oil-burning power station.
A great deal of debate goes into risks from various energy production and distribution technologies. For some reason, beyond me, nuclear power seems to take the most flak.
Now, ALL energy technologies kill people. Windmills break blades and cause injury, hydroelectric dams burst, people fall from roofs cleaning snow from solar cells or they die from the pollution from fossil fuel or nuclear power generation.
Technologies we perceive as safe, like solar cells, also produce very little energy -- particularly when we account for the energy required to manufacture and deploy them. Therefore, we need a safety figure-of-merit that normalizes the risk with the energy produced.
Let me propose using the following:
Joules/Corpse
I expect, on this basis, the wood stove would come out about the worst and nuclear energy the best. It would also be fun watching spin groups around the world working to skew the figures.
The ozone hole was discovered back in 1958 by the British Antarctic Survey. At the time, they saw it as a natural phenomenon caused by the South Atlantic Vortex -- a well established air movement pattern.
Now, there may be some real science behind CFCs and ozone depletion. The original lab work that demonstrated the chemistry was real. However, most of the material that comes my way about CFCs in the atmosphere seems more like spin than science. Maybe someone here can point us to some more measured and competent publications than I have been able to find.
Before we jump to too many conclusions about all the anti-CFC material, we should bear in mind it is standard practice for corporations to seek methods for making obsolete materials for which the patents have expired. Some creative lobbying and legislation is a great way to stop third-world companies turning out your products on the cheap.
I sounds a little like the "Infinite Improbability Drive." Maybe the Vogons can help.
It is a little like saying to someone from Montreal, "Your from Canada... You must know my aunt Mary in Vancouver."
Seriously, I visited a display on the SNO at the Sudbury Science Center. I was particularly taken by a specimine of the photomultiplyer tube they were using. It was a good meter in diameter and must have weighed 500kg. From memory, there are several thousand of them in the SNO.
If you are ever in Sudbury, the Science Center is well worth a visit. It one of the few science museums I have seen with a real sensitivity for science and scientific method.
I wonder how long it will be before we see 80's - style copy protection on software appear again?
I wonder if spinning mercury mirrors could form a good basis for searching for earth-orbit crossing asteroids. It would mean building a telescope at every few degrees of latitude and using the Earth's rotation for scanning.
The price of the optics could be right but the data-management task would be huge. It would also mean finding countries where the military would not get too bent-out-of-shape with people doing whole-sky scans -- I expect that rules out the USA.
I have seen fairly small mercury mirror systems (aperture of about 1 meter) and the technology is within the range of gifted hobbyists. Perhaps volunteer groups around the world could make such a system with some expert help.