Christmas Lecture.

[Mike Swift]

We've watched the Christmas Lecture since Adam was a lad and I can't say
there was a really bad one even when Channel 4 took over.

This year sadly we lasted 15 minutes, what a load of dingo's kidneys,
utter shambles presented by people who ticked a box and further ruined
by the stupid Zoom stuff of children, why not get a professional to give
the Lecture without an audience.

My wife commented that it was aimed at CBeebies, I said not to insult
them as it was far below their intelligence.

The utter rubbish transmitted over Christmas convinces me that the BBC
should be closed down, £157.50 a year licence is not good value any
more.

Mike

--
Michael Swift We do not regard Englishmen as foreigners.
Kirkheaton We look on them only as rather mad Norwegians.
Yorkshire Halvard Lange

[Calum]

On 29/12/2020 01:18, Mike Swift wrote:
> This year sadly we lasted 15 minutes, what a load of dingo's kidneys,
> utter shambles presented by people who ticked a box and further ruined
> by the stupid Zoom stuff of children, why not get a professional to give
> the Lecture without an audience.

I didn't watch it, but all the presenters are respected experts in their
field, they've all lectured in academic institutions, and they've all
presented numerous BBC TV programmes over the past 10 years. If there
was anything wrong with it, it doesn't sound like it was down to any
lack of professionalism on the presenters' part.

[Mike Swift]

In article <rsfpi5$4c2$1...@gioia.aioe.org>, Calum
<com....@nospam.scottishwildcat> writes

Then it was the writers and producers, it was just as bad again last
night.

[Andy Burns]

Mike Swift wrote:

> it was just as bad again last night.

The beginning of the first episode was cut-off, did it start early?

Twice I've started out watching it, and was interrupted by something
else, but so far there wasn't enough of interest to make me go back to
start watching again.

[Richard Evans]

On 29/12/2020 01:18, Mike Swift wrote:

> why not get a professional to give
> the Lecture without an audience.

It sounds like your main complaint was the quality of videos of the
audience. Well wouldn't is cost a fortune to install professional
quality equipment at all the schools and homes. Would that really be
justifiable ?

I found the poor technical quality took me by surprise, but only because
I'd forgotten that things would have to be different because of Covid.
Once I got past that, I thought they did about as well as could be expected.

I'm looking forward to seeing the next program.


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Jim S]

In article <rsielp$4gr$1...@gioia.aioe.org>, R.P.Evan...@Sky.com
says...

>
> On 29/12/2020 01:18, Mike Swift wrote:
> > why not get a professional to give
> > the Lecture without an audience.
>
> It sounds like your main complaint was the quality of videos of the
> audience. Well wouldn't is cost a fortune to install professional
> quality equipment at all the schools and homes. Would that really be
> justifiable ?
>
> I found the poor technical quality took me by surprise, but only because
> I'd forgotten that things would have to be different because of Covid.
> Once I got past that, I thought they did about as well as could be expected.
>
> I'm looking forward to seeing the next program.

As a former science teacher it think was always going to be a problem
having children not in the same room, but I think it was OK.
I have watched episode two so far. I wish I had had the gizmos tho'
It was always the joy of teaching physics as we had the best machines to
play with. :)

--
Jim S

[Peter Johnson]

On Wed, 30 Dec 2020 17:50:47 +0000, Richard Evans
<R.P.Evan...@Sky.com> wrote:

>
>I'm looking forward to seeing the next program.

I thought the second two were better than the first, and they had less
interaction with the kids, or it might be that their presenters were
better.

[Jim S]

In article <hd2sufli9sv1nra6h...@4ax.com>,
pe...@parksidewood.nospam says...

Agreed. Particularly the second one.
Introducing the format probably clogged up the beginning of the first
one, although I agree that he was the weakest presenter (and had the
fewest toys to play with).
The age range seemed too wide and the topics presented may have been too
sophisticated for the younger audience who visibly fidgeted*. Some of
the older ones in schools had a 'minder', just in case?
* it is well known that the concentration span of even mature students
is about 30 minutes and that is when they are in the same room as the
presenter!
--
Jim S

[Jim S]

PS
Finished the third today. The one with the 'shouty' Irish lady.
I thought the Taraworld analagy was 'political'!
BUT MOST OF ALL at no point did she explain why it's called 'Greenhouse
Effect'. I suspect many adults don't know the reason either.
--
Jim S

[Gordon Freeman]

Jim S <j...@jimXscott.co.uk> wrote:

> BUT MOST OF ALL at no point did she explain why it's called 'Greenhouse
> Effect'. I suspect many adults don't know the reason either.

My PVR watched the lectures for me so I haven't seen them yet but the
ironic thing about the Greenhouse Effect is that greenhouses themselves are
not warmed through the greenhouse effect! So really it should be called the
"global warming effect" or something.

[Halmyre]

As a former mature student, 30 minutes was really pushing it. Especially with one particular individual on Friday afternoons whose lectures defied all caffeine-induced attempts to retain consciousness.

[Richard Evans]

On 06/01/2021 02:49, Gordon Freeman wrote:
> the
> ironic thing about the Greenhouse Effect is that greenhouses themselves are
> not warmed through the greenhouse effect!

That's a new one on me. Doesn't the glass allow the sunshine in, while
being more of a barrier to the Infra red trying get back out again.
Isn't this the same basic principle of the Greenhouse effect?

[Max Demian]

On 30/01/2021 09:17, Richard Evans wrote:
> On 06/01/2021 02:49, Gordon Freeman wrote:
>> the
>> ironic thing about the Greenhouse Effect is that greenhouses
>> themselves are
>> not warmed through the greenhouse effect!
>
> That's a new one on me. Doesn't the glass allow the sunshine in, while
> being more of a barrier to the Infra red trying get back out again.
> Isn't this the same basic principle of the Greenhouse effect?

That's my understanding. Infrared from the Sun has a higher frequency
due to the higher temperature of the surface of the Sun; plants and soil
&c. in the greenhouse are a lot cooler and so their infrared has a lower
frequency, which is blocked by the glass.

I don't know whether global warming works the same way or not.

--
Max Demian

[Andy Burns]

Richard Evans wrote:

> Gordon Freeman wrote:
>
>> the ironic thing about the Greenhouse Effect is that greenhouses
>> themselves are not warmed through the greenhouse effect!
>
> That's a new one on me. Doesn't the glass allow the sunshine in, while
> being more of a barrier to the Infra red trying get back out again.
> Isn't this the same basic principle of the Greenhouse effect?

They put a coating on some glass to reduce the ir that's allowed back
out, IIRC it's something like 90% for plain glass, 25% for "K" glass but
I doubt many greenhouses have it?

[Jim S]

In article <rv3880$ept$1...@gioia.aioe.org>, R.P.Evan...@Sky.com
says...

>
> On 06/01/2021 02:49, Gordon Freeman wrote:
> > the
> > ironic thing about the Greenhouse Effect is that greenhouses themselves are
> > not warmed through the greenhouse effect!
>
> That's a new one on me. Doesn't the glass allow the sunshine in, while
> being more of a barrier to the Infra red trying get back out again.
> Isn't this the same basic principle of the Greenhouse effect?

I do hope so, as that's what I taught for donkey's years, although I
doubt whether they knew it applied to the whole atmosphere back then. I
believed (and still do) it is to do with the wavelength emitted by the
heat source. The sun being slightly warmer than the pot plants and
therefore shorter wavelength.
I have been watching (by accident) an advert singing the praises of
lining your conservatory roof with what appears to be white polyurethane
(?) as it is cheaper than roofing properly. Surely once the heat has
passed through the glass then it's too late - yer doomed :)
I must admit that I am a bit smug as my friends who had all-glass
conservatories, suddenly stopped being in denial that they were too hot
in the summer and too cold in the winter. Not because I told them, but
because some 'persuader' on TV did.

--
Jim S

[Dave W]

So why is it called the Greenhouse Effect?
--
Dave W

[Richard Evans]

On 30/01/2021 10:52, Max Demian wrote:
> That's my understanding. Infrared from the Sun has a higher frequency
> due to the higher temperature of the surface of the Sun; plants and soil
> &c. in the greenhouse are a lot cooler and so their infrared has a lower
> frequency, which is blocked by the glass.

A tiny correction. The principle is correct. Bodies with higher
temperatures do emit higher frequencies. I'd point out that
the frequencies from the sun are high enough so that visible light
carries more energy than any other frequencies. I assume, the radiation
from the greenhouse gets as high as Infrared. Although come to think
of it, I'm not certain that it gets that high. I would think it would
be somewhere in the Infrared part of the spectrum.

> I don't know whether global warming works the same way or not.

Basically yes. Hardly any of the high frequencies from sunlight are
absorbed directly by the atmosphere. Instead they heat the ground.
The much lower frequencies from the ground are absorbed by gasses
such as CO2, so they reduce the rate at which heat escapes. Actually
we need some Greenhouse effect, as otherwise our temperatures would be
more like -15, but we are starting to get too much.

Richard.

[Richard Evans]

On 30/01/2021 13:09, Jim S wrote:

> I have been watching (by accident) an advert singing the praises of
> lining your conservatory roof with what appears to be white polyurethane
> (?) as it is cheaper than roofing properly. Surely once the heat has
> passed through the glass then it's too late - yer doomed :)

Could that be stopping conduction, as well as radiation ?

[Jim S]

In article <rv6dvn$108q$2...@gioia.aioe.org>, R.P.Evan...@Sky.com
says...

>
> On 30/01/2021 13:09, Jim S wrote:
>
> > I have been watching (by accident) an advert singing the praises of
> > lining your conservatory roof with what appears to be white polyurethane
> > (?) as it is cheaper than roofing properly. Surely once the heat has
> > passed through the glass then it's too late - yer doomed :)
>
> Could that be stopping conduction, as well as radiation ?

Who knows. All of the people ALL of the time :)

--
Jim S

[Max Demian]

On 31/01/2021 14:10, Richard Evans wrote:
> On 30/01/2021 10:52, Max Demian wrote:
>> That's my understanding. Infrared from the Sun has a higher frequency
>> due to the higher temperature of the surface of the Sun; plants and
>> soil &c. in the greenhouse are a lot cooler and so their infrared has
>> a lower frequency, which is blocked by the glass.
>
> A tiny correction. The principle is correct. Bodies with higher
> temperatures do emit higher frequencies. I'd point out that
> the frequencies from the sun are high enough so that visible light
> carries more energy than any other frequencies. I assume, the radiation
> from the greenhouse gets as high as Infrared. Although come to think
> of it, I'm not certain that it gets that high. I would think it would
> be somewhere in the Infrared part of the spectrum.

If visible radiation has more energy than infrared, why do I get the
impression that the latter has more warming effect than the former?

--
Max Demian

[Richard Evans]

On 31/01/2021 22:50, Max Demian wrote:
>
> If visible radiation has more energy than infrared, why do I get the
> impression that the latter has more warming effect than the former?

That's not quite what I meant.

I thought one on my earlier comments
had mislead you, (and I'm finding it hard to explain why.) I had said

"Doesn't the glass allow the sunshine in, while being more of a

barrier to the Infra-red trying get back out again". From your reply
I got the impression you though it was only the Infra-Red that matters.
Well actually, at the part when I said Infra-red, I was referring just
to the radiation trying to get out, which would not contain any visible
frequencies. So I said Infra-red. Sunshine does contain more than
infra-red, it also contains visible and above. Basically it's just
the frequencies that matter. (BTW. there will also be some below
Infra-Red, but the power of this would be insignificant).

I actually meant that the peak power from sunlight is in the visible,
(which is probably largely why our eyes evolved for it.) Although,
since the visible band is such a narrow band, and there are far more
IR frequencies. I assume the total of all the IR frequencies would
add up to more, although the individual frequencies would be less.

Also, I suspect we may be more likely to think of IR as a band of heat,
as we can't see it. So if it is strong, we would feel a heat while not
being able to see that it's strong.

[Gordon Freeman]

Richard Evans <R.P.Evan...@Sky.com> wrote:

> On 06/01/2021 02:49, Gordon Freeman wrote:
>> the
>> ironic thing about the Greenhouse Effect is that greenhouses
>> themselves are not warmed through the greenhouse effect!
>
> That's a new one on me. Doesn't the glass allow the sunshine in, while
> being more of a barrier to the Infra red trying get back out again.
> Isn't this the same basic principle of the Greenhouse effect?

Yes that's the principle of the greenhouse effect, but in fact
greenhouses warm up mainly because the glass prevents convection - the
warmed air inside is kept from mixing with the cooler air outside, so
the heat builds up. Someone proved it by glazing a greenhouse with
special glass that is totally transparent to infrared and it stayed just
as warm.

So the "greenhouse effect" warms the planet but not greenhouses! But it
doesn't matter because the phrase is only used in relation to
climatology, not horticulture. But "global warming effect" would perhaps
have been better.

[Max Demian]

On 03/02/2021 02:16, Gordon Freeman wrote:
> Richard Evans <R.P.Evan...@Sky.com> wrote:
>
>> On 06/01/2021 02:49, Gordon Freeman wrote:
>>> the
>>> ironic thing about the Greenhouse Effect is that greenhouses
>>> themselves are not warmed through the greenhouse effect!
>>
>> That's a new one on me. Doesn't the glass allow the sunshine in, while
>> being more of a barrier to the Infra red trying get back out again.
>> Isn't this the same basic principle of the Greenhouse effect?
>
> Yes that's the principle of the greenhouse effect, but in fact
> greenhouses warm up mainly because the glass prevents convection - the
> warmed air inside is kept from mixing with the cooler air outside, so
> the heat builds up. Someone proved it by glazing a greenhouse with
> special glass that is totally transparent to infrared and it stayed just
> as warm.

Dang! Another 'fact' bites the dust!

--
Max Demian

[Richard Evans]

On 03/02/2021 02:16, Gordon Freeman wrote:

>

> Yes that's the principle of the greenhouse effect, but in fact
> greenhouses warm up mainly because the glass prevents convection - the
> warmed air inside is kept from mixing with the cooler air outside, so
> the heat builds up. Someone proved it by glazing a greenhouse with
> special glass that is totally transparent to infrared and it stayed just
> as warm.
>
> So the "greenhouse effect" warms the planet but not greenhouses! But it
> doesn't matter because the phrase is only used in relation to
> climatology, not horticulture. But "global warming effect" would perhaps
> have been better.
>

Perhaps 'Greenhouse Effect' refers more to the fact that heat can
get in, but it less able to get out. This would be true of both
greenhouses and the atmosphere. Perhaps the details of how
exactly the heat gets trapped have been forgotten along the way.

[Jim S]

In article <M_KdnSRklaIrOIf9...@brightview.co.uk>,
max_d...@bigfoot.com says...

I wonder about 'someone', 'special "glass"', 'totally''transparent to
infra red' - without seeing more evidence.

--
Jim S

[Gordon Freeman]

I think I heard about it on Home Planet, either that or some other Radio
4 science programme. My reollection was that quartz was used but I just
looked it up and in fact it seems rock salt was used to make a "glass"
pane that was transparent to infrared:

<https://berkeleysciencereview.com/2016/11/greenhouse-gases-versus-glass-
greenhouses/>

[Calum]

On 03/02/2021 23:45, Gordon Freeman wrote:

> I think I heard about it on Home Planet, either that or some other Radio
> 4 science programme. My reollection was that quartz was used but I just
> looked it up and in fact it seems rock salt was used to make a "glass"
> pane that was transparent to infrared:
>
> <https://berkeleysciencereview.com/2016/11/greenhouse-gases-versus-glass-
> greenhouses/>

However, from the same article...

"To the best of my knowledge, Robert W. Wood’s experiment was
unreplicated until 2009, when Stanford Professor Vaughan R. Pratt put it
to the test using very thorough internal controls and modern technology.
Dr. Pratt failed to reproduce Wood’s work: he found that the box with
the glass cover (greenhouse analog that trapped infrared light) was
several degrees warmer than the one with the salt lid (the one that did
not block any infrared light)."

[Jim S]

In article <rvghaa$12od$1...@gioia.aioe.org>,
com....@nospam.scottishwildcat says...

>
> On 03/02/2021 23:45, Gordon Freeman wrote:
>
> > I think I heard about it on Home Planet, either that or some other Radio
> > 4 science programme. My reollection was that quartz was used but I just
> > looked it up and in fact it seems rock salt was used to make a "glass"
> > pane that was transparent to infrared:
> >
> > <https://berkeleysciencereview.com/2016/11/greenhouse-gases-versus-glass-
> > greenhouses/>
>
> However, from the same article...
>

> "To the best of my knowledge, Robert W. Wood?s experiment was

> unreplicated until 2009, when Stanford Professor Vaughan R. Pratt put it
> to the test using very thorough internal controls and modern technology.

> Dr. Pratt failed to reproduce Wood?s work: he found that the box with

> the glass cover (greenhouse analog that trapped infrared light) was
> several degrees warmer than the one with the salt lid (the one that did
> not block any infrared light)."

So...it didn't work then?
And here's me thinking I was unnecessarily sceptical :)

--
Jim S

[Gordon Freeman]

If you read the accompanying experiment report it's more complicated
than that. When they recreated the experiment properly they found the
air at the base of the two boxes heated to the same temperature (about
twice ambient temperature) but the air at the top of the box just under
the glass was 40% warmer with glass and 32% warmer with rock salt. They
couldn't account for there being a difference in readings at the top but
not at the bottom, but if we consider just the temperature at the top it
would suggest the warming was 75% due to the air being trapped under the
cover and 25% to the infrared being blocked by the glass. But for a real
greenhouse I would have thought the ground level temperature would be
most important as that's where the plants are and the temperature there
wss the same.

As to the differences between top and bottom, I assume the sunlight
initially heats the base of the box without significantly heating the
air on the way through. The air is then heated by contact with the
ground.

But the air at the top would also get heated a bit from being in contact
with the glass, and their readings show the surface temperature of the
glass pane averaged 1.2 degrees warmer than the rock salt one despite
periodically swapping everything around to make sure conditione were
identical. This suggests the glass pane absorbs more of the suns heat
(presumably the the infrared element of the sunlight), and so may heat
up the air just under the glass a bit more than the rock salt one does.

Unfortunately they don't give any indication of the thermal conductivity
etc of the two types of glass, they simply say they are the same
thickness.