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Sunlight and heat

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 Flinticus 10 Sep 2022

What's the term for the transfer of energy via sunlight into heat on a body in that sunlight.

 broken spectre 10 Sep 2022
In reply to Flinticus:

Absorbtion?*

*I'm not a scientist, mind.

 broken spectre 10 Sep 2022
In reply to Flinticus:

Google is suggesting it's spelt **absorption**

 NobleStone 10 Sep 2022
In reply to broken spectre:

Radiation

1
 broken spectre 10 Sep 2022
In reply to NobleStone:

But radiation refer to the emission of the electromagnetic rays (in this case) whereas the OP is asking for a term for the transfer of energy when the photons hit something?

 hang_about 10 Sep 2022
In reply to Flinticus:

Infrared light emitted (radiated) from the sun is absorbed by an object (the process of absorption) causing it's temperature to rise. Never knew why the b p difference exists. We need a Greek or Latin scholar (but no one called Boris please)

In reply to Flinticus:

Insolation

 birdie num num 10 Sep 2022
In reply to Flinticus:

It's known as a suntan 

OP Flinticus 11 Sep 2022
In reply to hang_about:

Interested in that there seems to be a lack of lay person guidance on the effects of solar radiation on days that are not warm, i.e. high pressure cool or cold days.

Yesterday the temps were noted as mild, especially in the mountains,  but it was a cloudless day and I noted that the 'fur" on my long haired dog became warm to the touch and was affecting her (and I bailed out into a cooler shaded glen). Yet, the headline temps from the Met had led me to think temps would not be an issue 

I noted a similar effect previously on another high mountain, this time she had been dipped in a large cool loch and there was a good cooling wind but neither stopped her coat heating up.

She seems to absorb a lot of heat energy from direct sunlight... 

 jdh90 11 Sep 2022
In reply to Flinticus:

Sometimes called solar gain, at least when used in reference to a room or building.

Edit: oh and one more possible term, I was set a third year project in my degree with a tile that started "Photothermal heat transfer model of a...". So I used that term a lot in the report.

Post edited at 19:10
In reply to Flinticus:

Absorption

Why make it more complicated? If radiation (IR) can be emitted at one side (e.g. sun) it's absorbed at the other side (e.g. dark coloured dog)

Post edited at 20:19
 henwardian 11 Sep 2022
In reply to CantClimbTom:

> Absorption

Yes, this is the scientific word I would use. Obviously there are various fields dealing with the phenomenon so there will be a few other words/phrases like those other people have mentioned.

Edit: Also, in chemistry I would use "emission" more often than "radiation" but unless you are doing something extremely specialist I suspect this is a potato potahto situation.

> Why make it more complicated? If radiation (IR) can be emitted at one side (e.g. sun) it's absorbed at the other side (e.g. dark coloured dog)

It is more complicated though because it's not just IR wavelength radiation from the sun that heats you up. If it was possible to filter all the IR radiation out of sunlight, you would still heat up from the energy absorbed into your skin surface from the other wavelengths (though ofc plenty would also reflect off your skin). A good example of this is that you can use a laser that emits basically no IR radiation at all to melt steel, set fire to trees, etc.

Post edited at 23:50
 aln 12 Sep 2022
In reply to henwardian:

> A good example of this is that you can use a laser that emits basically no IR radiation at all to melt steel, set fire to trees, etc.

That sounds cool. Can you link to some examples? 

 NobleStone 12 Sep 2022
In reply to Flinticus:

It's complicated and not very intuitive to teach, but something you get used to if you spend a lot of time outside, especially in the mountains. I think most climbers have had days cragging in the winter when they only need a tee shirt as the sun is shining and they are sheltered from the wind. Then you top out and you need a duvet. 

My other half, who is from a warm part of the world and not very outdoorsy, is constantly baffled by picking the right clothing for the weather, but usually only looks at forecast temperature. I make my judgement based on temperature, windspeed, cloud cover, humidity and how active I'm going to be.

The same is true indoors, once air movement is taken out the equation, the biggest impact on thermal comfort is radiative heat loss (or whatever you want to call it). Tackling this means people can be comfortable in cooler air temperatures, but most people get obsessed with their thermometer rather than how they feel.

 jimtitt 12 Sep 2022
In reply to aln:

> > A good example of this is that you can use a laser that emits basically no IR radiation at all to melt steel, set fire to trees, etc.

> That sounds cool. Can you link to some examples? 

The laser welders for copper, gold etc emit in the blue or green colour spectrum because these materials absorb the light vastly better than IR which is the more normal welder wavelength. One saves 80-90% of the energy used by a traditional laser welder.

 minimike 12 Sep 2022
In reply to broken spectre:

Absorption of electromagnetic radiation

Or warmth of the sun as we call it at home

 wercat 12 Sep 2022
In reply to minimike:

> Absorption of electromagnetic radiation

by electrons

 minimike 15 Sep 2022
In reply to wercat:

Molecules. 

 tcashmore 15 Sep 2022
In reply to Flinticus:

Its fundamentally electromagnetism - transfer of energy via the electromagnetic 'force' between photons and electrons

 kevin stephens 15 Sep 2022
In reply to Flinticus:

There's radiant temperature, eg experienced in space where there's no atmosphere.  Your body (spacesuit) will warm up until the radiant energy emitted from your spacesuit to cold dark space equals the radiant energy absorbed from the sun by your space suit.

Then there's air temperature; eg on earth during a cloudy night where your body will warm or cool to match the air temperature

The relative impact of air temperature and radiant temperature (ef on a sunny winter's day) will depend on the properties of the body concerned.  For humans wearing clothes the mean Environmental temperature is defined as 1/3 radiant , 2/3 air (or conductive/convective) temperature

Post edited at 11:56
 subtle 15 Sep 2022
In reply to Flinticus:

Dunno, all I know is that this morning there was plenty of sunlight but nae heat - it was feckin freezin despite the sun being out!

Guess that's September for you, we should just be grateful its dry and sunny I suppose

 henwardian 15 Sep 2022
In reply to aln:

> > A good example of this is that you can use a laser that emits basically no IR radiation at all to melt steel, set fire to trees, etc.

> That sounds cool. Can you link to some examples? 

A guy with a home-made irresponsibly powerful laser:

youtube.com/watch?v=W6FbUiiwutQ&t=713   (The timestamp is where he actually points it at stuff.)

And metal cutting machines:

youtube.com/watch?v=r5vsUta5lmo&

 magma 15 Sep 2022
In reply to kevin stephens:

re. radiant temp/photon pressure and air temp, did you ever have a https://en.wikipedia.org/wiki/Radiometer as a child? never knew they could turn both ways depending on amount of vacuum..


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