Markit
Picasa Web Albums - Markit - 2010-03-06
For all of you that are still interested some even newer pictures - well, that actually kind of depends upon when you are reading this so have included a date too.:icon_wink:
Butch
Great pics Markit. Good to have a roof over head so you can get started on the inside.
I was wondering what the go is with the lightning rods. I understand it's good to get the strike to ground if it does happen but what's the chance of getting hit. You've got heaps of coconut trees around you. Wouldn't they be a natural target/ground for lightning? Is there that much lightning in your area that calls for these measures? Not having a go just doesn't seem to be a priority when building here.
Jimbo
[I]t is a good job our HSE department is not on your site but a great project. What will you do when its finished?[/I]
Jesse
Wow. The development of the house is getting better. I wonder when will your building be completed.
tintin
If the Al foil reflects the heat, then how to you account for the baked potatoes in Al foil, in an oven? Better check your physics, Markit...:icon_lol:
ronb
tintin wroteIf the Al foil reflects the heat, then how to you account for the baked potatoes in Al foil, in an oven? Better check your physics, Markit...:icon_lol:
Well I'm no physicist, but non-microwave ovens get the heat to the food by a mixture of radiation and convection. The alfoil around the potato will surely reflect a proportion of the radiant heat arriving, but this heat will just bounce around inside the oven and help the convection process. So no matter how reflective the alfoil is, in the end the alfoil gets hot, the potato gets hot and cooks.
Markit
tintin wroteIf the Al foil reflects the heat, then how to you account for the baked potatoes in Al foil, in an oven? Better check your physics, Markit...:icon_lol:
Typical, you question my roof rather than your potatoes:icon_wink:
Butch wroteGreat pics Markit. Good to have a roof over head so you can get started on the inside.
I was wondering what the go is with the lightning rods. I understand it's good to get the strike to ground if it does happen but what's the chance of getting hit. You've got heaps of coconut trees around you. Wouldn't they be a natural target/ground for lightning? Is there that much lightning in your area that calls for these measures? Not having a go just doesn't seem to be a priority when building here.
Lightening is a funny old thing - it will usually hit the highest object - the operative word here is "usually" - sometimes it just decides to go just a little to the left or right - are you willing to bet the house on that? Lightening rods also fulfil a preventative function in that they siphon the energy out of a potential thunderstorm before it gets "mad".
Jimbo wrote[I]t is a good job our HSE department is not on your site but a great project. What will you do when its finished?[/I]
Good question Jimbo... wanna buy it?
Jesse wroteWow. The development of the house is getting better. I wonder when will your building be completed.
Never, ever, ever... it seems endless:icon_rolleyes:
ronb wroteWell I'm no physicist, but non-microwave ovens get the heat to the food by a mixture of radiation and convection. The alfoil around the potato will surely reflect a proportion of the radiant heat arriving, but this heat will just bounce around inside the oven and help the convection process. So no matter how reflective the alfoil is, in the end the alfoil gets hot, the potato gets hot and cooks.
In my experience the foil only seems to keep them from drying out. Back in LOF-HOB (land of the free, home of the brave - USA) they used to originally only do foil on the tates when we put em in the barby with the shinny side out to slow em down a little...
tintin
In the case of the baking of a potato, the only reason why a tinfoil is used is to retain the moister inside the potato and keep its skin moist. As one puts the wrapped potato inside the oven, the temperature of the Al foil almost perfectly tracks that of the surrounding air. Very little heat transfer to the Al is due to radiations, but practically all of it is due to heat conduction, between the air and the Al foil, which in turns heats up the potato. But for all practical purposes, it's as if the Al foil was not there.
The same is true with your roof. The tiles, which are heated up by the sun radiation and the surrounding air through conduction and to a small extend, convection, heat up the Al foil by conduction (just as the air does in the oven), which in turn heats the room below.
The advantage of an alang-alang over tiles is that the former is not a good heat conductor, therefore becoming an insulator for the room underneath.
Actually, although you are not from Texas, I think you've read too many William Faulkner's novels...:icon_biggrin:
Markit
Actually red tiles are almost as good a reflector of heat as white - but I agree the aluminium foil is pointless. It was easier to agree then to fight about it and it is very cheap too. "When in Rome, do as the Romans".
tintin
Markit, [U]just for fun[/U].
Definition, albedo: the fraction of incident electromagnetic radiation reflected by a surface.
You will be surprised to know that the albedo for,
- Red tiles = 0.3
- White plaster = 0.93
- Bright Aluminum foil = 0.85
I knew that the albedos of white surfaces were superior to colored ones (in this case, 3 times better), but it is surprising to find out that a white plaster surface should be a little more efficient at reflecting radiations than bright Al foil (I sure hope this latest finding does not prevent me from sleeping to night):icon_biggrin:
PS. Really enjoy your pictures documenting the progress of the building of your house. Keep them coming.
Jesse
Markit wrote....
Never, ever, ever... it seems endless:icon_rolleyes:
...
It's usually the excitement that beats the temper. I hope it would be completed by 3 months... :)
JUDY
Markit, your house looks beautiful. You are going to live in it, not sell it down the road are you? Great job. Thought you were retiring in Bali with your family. Love the pool.
Markit
Thanks Tin,
One further question: my, admitted aged physics knowledge reminded me that the light reflected is not only that frequency, be it red, blue or white, but contains all lower frequencies spectrum too. For instance: white objects will contain all visible frequencies but red objects will only reflect and contain frequencies lower in the spectrum?
Is your area of expertise physics? if so which specific teaching?
Markit
Markit
Thanks Tin, when I said "It was easier to agree then to fight about it" I meant with the locals, not you.
I read somewhere that red roof tiles are just slightly less hear reflective than white ones - can't find the source now, of course but it did make some sense at the time, heat being in the infra red scale of the spectrum. And terracotta tiles being - red.
But my source didn't mention a 300% difference. I did broach the subject of using white tiles with my architect but he was so offended by the mere idea "You would be alone on Bali! Can not do!" I didn't have the heart to do it although I did look into it a little more in the form of painting some red tiles with a good covering of white paint which I left out to weather for a couple of months. The results where sort of pinkish... very "Gay" as my daughter said.
tintin
You got the idea, but you don't have all the "pieces of the puzzle." What I will try to explain, I am sure you know most of it already, but the WHOLE picture must be considered.
-The sun emits a whole spectrum of electromagnetic radiations, from high frequency x-ray (short wave lengths) to extreme infrared (long wave lengths).
-Thia solar spectrum is closed to a "black body" spectrum of 5,785 degrees Kelvin (5,512 degrees C), which peaks in the visible range of the spectrum, at about 4.750 (.blue), at the top of Earth's atmosphere, and more in the greenish, at about 5,250 Angstroms, at sea level.
-These radiations are made up photons, each carrying a certain amount of energy, the higher the photon's frequency, the more energy it carries. Therefore, a violet photon has more energy than a red photon.
- An object has a given color given by the wave length of the photons that it reflects most: a red object appears red because it reflects mostly "red" photons, and absorbs the rest, a blue object reflects the "blue" photons, and appears blue, etc. A black object does not reflect any of the visible spectrum wave lengths and therefore appears black. Thus, if you illuminate your red tiles with, for example, only blue light, they would appear black, because there are no "red" photons to be reflected.
So, the red tiles will reflect the red wave length ONLY (but NOT the infra-red photons). They will absorb all the other photons of different wave length, and the shorter the wave length, the more energy each photon carries, and this energy will be transferred to the tiles.
Energy is of course CONSERVED (one of the most basic physics principle). So this energy transferred to the tiles contributes to shaking the s**t out of the molecules which make up the material of the tiles. But molecules vibrate at low frequencies (long wave lengths) and will re-emit this energy at longer wavelength, in the infra-red, which is called in every day life, "heat."
I hope this explanation is clear (the exam will be closed book, next week)
It all comes down simply, as mentioned before, to the albedo of a given object: the darker the color, the more it absorbs the solar radiations, the easier it heats up.:icon_biggrin:
tintin
You are correct.
VERY simply, photons of all frequencies impinging on an opaque surface interact with the molecules of that surface. The photon will either be reflected "specularly" (like a mirror), scattered (reflected with diffuse scattering, i.e. in all directions), or absorbed – or some combination of these three possibilities. Opaque objects, like the tiles, which have rough surfaces that do not reflect, have their color determined by which wavelengths of light they scatter more, due to there molecular composition.
A very small amount, maybe 1 in 10 – 100 million photons (depending on the scattering material) of the scattered light will be scattered by an excitation (this is called the Raman effect). In that case, its energy will be reduced, that is to say that, like you said, its frequency will be reduced. In the case of the red tiles being illuminated by a red laser, a VERY small amount of the scattered light will also contain a VERY small amount of "redder" photons, and one could really see it (Raman Spectroscopy). In the case of solar illumination, what is called "red" will be the sum of the red and redder photons, and we won't know the difference.
I hope my explanation is not too garbled.
Your other question. 40 years of research in the field of nuclear physics, astrophysics (x-ray astronomy), and applied x-ray physics. Taught several years at Caltech, (2), Ohio State U. (2), and Northeastern U. (part time, 6)
mat
Great pics and a handsome looking house and pool.
I like the Al foil, not only good for reflecting heat but also a barrier for insects and minor leaks.
tintin
mat wrote
I like the Al foil, not only good for reflecting heat...
Brings back old memories. I remember when I was teaching, there was ALWAYS a student in each class who came to the lecture just to sleep...:icon_rolleyes:
Markit
Ok Tin I got a question that's been buggin me for years and years and it is about as far off-topic as you can get - but it's my topic so I can do this I hope?
We (us plebs) are always being told that (voice of Carl Sagan "billions and billions and billions").
"These pictures from our fantastic Mega-buster, Super Acme Pretty Neat Neutron Telescope show the universe as it was 14 billion years ago back at the time of the big-bang."
Now if I follow this correctly we (the universe, my baseball card collection and all videos of Tracy Lords) at the time of the big bang (or as close as you can get) were about the size of a pin head (I know, no pins then either).
[B]Bang![/B] Everything (the universe, my baseball card collection and all Tracy Lords videos too) start to expand at what ever rate matter does in that situation - [B]but[/B]! slower than the speed of light!!! Right?
My question is: if we have been expanding at a rate slower than the speed of light how can we get pictures made from any radiation that travels on or about the speed of light which passed us (tracy lords, cards, etc.) by about 1 trillionth of a second after the big bang. And has been ahead of us expanding for the last 14 billion years?
It seems to me it would be about like trying to use your camera flash to take a picture of your camera flash attachment - if that makes any sense?
Thanks for any info
Markit
Jesse
tintin wroteBrings back old memories. I remember when I was teaching, there was ALWAYS a student in each class who came to the lecture just to sleep...:icon_rolleyes:
That reminds me too since I was also that kind of student. lols
