Re: Virgin at the bedroom window!

Sleepalot wrote:
JpinNY <jpinny@xxxxxxxxxxx> wrote:

Sleepalot wrote:
"Dave Liquorice" <allsortsnotthisbit@xxxxxxxxxxx> wrote:

On 22 Sep 2008 09:03:39 GMT, Johnny wrote:

I don't get that. How would something radiate their heat past ambient?
Rate of radiation is greater than the rate of absorption. Air is a pretty good insulator, if the air is fairly still the object radiates in infra red that doesn't warm the air. The air near the object will be cooled by the object but isn't replaced with warmer air from elsewhere so stays cool insulating the object which continues to radiate IR and thus get colder and colder.
That violates a law of thermodynamics: heat cannot pass from a
cold object to a warmer one (without doing work - as in a fridge).

It also contradicts the "Greenhouse Effect" in which CO2 acts
as an insulator, keeping the Earth's surface warm.
That's about the chemical composition of the surrounding atmospheric layers, isn't it?

As far as I know, they're all much the same. I suppose city smog is
chemically different - but that's a local thing.
But...

Air's not a heat insulator: it conducts, convects and radiates
(as does CO2). (Compare it to glass, which doesn't conduct well,
and doesn't convect.)
Um....air is flipping fantastic insulator! Yes it is.

Nope, sorry. Breath onto your hand: your breath is warm. The air
in your lungs heats up in seconds. Now, find a good heat insulator
(a bathroom tile or marble worktop) and try warming that with your
breath. It'll take a lot longer to warm up.


I wouldn't expect to be able to transfer much heat from my 37C body to a slab of marble by breathing on it! I could try sitting on it for a long time and some of the heat would be lost into the marble, if I weren't wearing my thermal (insulating) long-johns. You're talking to someone who has sat on cold metal (good conductor) bleachers (American name for tiered benches) watching her child play football on cold winter days, and I always take a fleece (air insulating) rug to sit on. I do not rely on breathing onto the bench.

If the slab of marble or metal bench was already warm from some other source of radiant heat or submersion in a hot fluid or contact with a warm object, then one could attempt to insulate it with some material which traps air.


That's how we keep warm in cold climates by trapping air, so long as it doesn't move about.

Ah, now we enter the realm of string-vest theory - you can guess where I stand on that one. ("He's predictable - but that's to be
expected.")

String vests work better in combination with another layer.

If we didn't have clothes, we could cover ourselves in paint, mud,
goose grease or chocolate spread, and be warmer without trapping
air.

The only way we would be warmer would be because of minute air bubbles trapped in the mud.

Sleepy-not-a-physicist
Jp isn't a physicist either !

Jp

.

Relevant Pages

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