Re: [GSAS-Member] CFL bulbs

["Paul M. Wallace" <pwallace@u.washington.edu>]

I love when those able to keep and breed things like *Shrimp* contribute to
the panel in November.

-Paul


-----Original Message-----
From: gsas-member-bounces@thekrib.com
[mailto:gsas-member-bounces@thekrib.com] On Behalf Of Shango Los
Sent: Thursday, October 22, 2009 2:35 PM
To: Greater Seattle Aquarium Society member chat
Subject: Re: [GSAS-Member] CFL bulbs

I love it when you engineer types in the club write emails like this!

Thanks!

On Oct 22, 2009, at 2:05 PM, Erik Olson wrote:

> On Thu, 22 Oct 2009, clayton anderson wrote:
>
>> Thanks Eric, so it sounds like color temp. (Kelvin) and wavelength  
>> are
>> independent, if I'm hearing you correctly.
>
> I wouldn't call them independent.  Think of a particular color  
> temperature
> as representing a certain mixture of the different wavelengths.
>
> Let me try to simplify in an example:
>
> In some not-so-great fluorescent bulbs, there are only three  
> wavelengths
> (or "spikes") in the spectrum.  red 600 nm, green 550 nm, and blue  
> 470 nm.
>
> One might make white light with a color tempeature of 3000K as 30%  
> red,
> 40% green and 30% blue.
>
> But 5000K might be more like 25% red, 43% green and 32% blue.
> And 8000K might be 18% red, 47% green, and the rest blue.
>
> In reality it's a continuum, not just three spikes.  The better tubes
> (higher Color Rendition Index) smear the spectrum instead of having  
> just
> three spikes.  But that's one reon people like sunlight, candlelight  
> and
> incandescent bulbs -- they are all so-called "black body radiators"
> and have a nice smooth spectrum.  The color temperature literally  
> means
> how hot the object is to produce that distribution of light.  Which  
> means
> that light bulb filament is 3000 degrees!
>
> http://en.wikipedia.org/wiki/Black_body
>
> And there actually IS a direct correlation between the color  
> temperature
> and the "peak" wavelength when dealing with the above. peak  
> wavelength =
> b / Color Temp.
>
> I have a few crappy drawings I did 12 years ago to illustrate some of
> this, though I like the wikipedia article better:
>
> http://www.thekrib.com/Plants/People/Darn/darn3.html
>
>
>   - ERrik
> -- 
> Erik Olson                                                         
> Sent from my crusty old Linux box
> erik at thekrib dot com
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