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Re: your mail
On Fri, 23 Feb 1996 KellySt@aol.com wrote:
> > Kelly,
> > >> I don't understand why you think it keeps the heat out
> > >> during daylight?
> > >> As far as I know, it keeps the heat in day AND night.
> > >
> > >Climatologists don't agree on that. Sun light has a large component in
> > >IR bands.
> > Yes, I know, but "earth-light" is even more intense in that
> > band.
> > (more intense relative to the sunlight that finds it way
> > to the soil)
> No sunlight is hotter in the IR band, and your not talking about the amount
> that gets to the ground, your talking about what hits the top of the
> atmosphere. IR reflective gasses would reflect that back out. Thus lowering
> the solar heat gain. Thus lowering the Earth surface temp during the day.
It isn't that sunlight is stronger or lower in the IR bands, it's that
earth-light is much much loser in the UV and visible bands.
the gases (or whatever) keeps IR from passing, so both solar IR and
earthly IR are reflected. The UV and Visible portions of the spectrum
usually pass right through and then strike the ground, but the ground
doesn't heat up enough to produce visible or UV radiation, so it's sent
out as IR. The diving force of the greenhouse is not the difference
between earthly IR and Solar IR, it is the difference between solar
Visible and UV and Earthly visible and UV (~0)
There is very strong data for a temp rise over the last 90-100 years.
The question is what caused it. Industrial appologists deny that it has
anything to do with them, while environmentalist Luddites want to return
to eighteenth century technology. Both are using the available data in
the same way that a drunk uses a lampost... not for illumination, but for
> No, I'm saying that introducing IR reflective gas wouldn't nessisarily heat
> up a planet that got most of its surface temp from outside sources. Given
yes, it depends on the frequency of the incoming radiation
> that a lot of IR reflective gas has been added to the atmosphere without
> changing the temp, and no one has a coherent explanation for how it would
that is not true. the _has_ been a temp rise over the last 90-100
years. It is small, and it cannot be _proven_ to be caused by the
greenhouse gases, but it has occured.
> increase the temp, and the whole idea is vigorously debated, I'ld say it
Only by those who are afraid to have industrial society collapse around
thier ears if the environmentalists win. The Industrialists are right
about one thing, we can't stop yet. if we quit burning petrochemicals,
we would be starving inside of three months. But the environmentalists
are right about something too, we _will_ one day have to stop burning
oil, because we are going to run out one day.
BTW, Space-based solar energy beamed down by microwave will not solve the
greenhouse problem, but will make it worse instead. Energy (microwaves)
would be entering the earth's atmosphere, (we'd choose a particularly
transparent frequency, to avoid losses) and then be consumed by various
items (television, motors, light-bulbs etc) which waste large amounts of
energy as heat. The heat would be held in just as it is now, (when
talking about a planet, radiation is the only means of heat shedding) But
there would be a much larger influx, because solar panels would be
collecting sunlight that would have otherwise missed the earth.
> > I now don't understand anymore why does it become warm
> > in a greenhouse?
> The glass keeps the cold wind out and is a slight insulator. It only works
> if its not really cold, and theirs still a lot of sunlight to warm it up in
> the day time.
Glass works, because it restricts the heat balance to radiation only by
preventing convection (i.e. it keeps the cold wind out.) or conduction
(i.e. it is a slight insulator) in that respect, it is just like the
vacuum of space, that vacuum prevents convection and conduction, and
restricts the heat-balance to radiation terms only.