question about colour temperature

firstly, i put this thread in the advanced section because i figured people in newbie central or general sections wouldn't be able to answer, and also because i understand colour temperature in relation to growing mj (when to use which bulbs and why etc.).

my question ultimately is what is the difference between colour temperature and spectrum?
why is it measured in kelvins if it is a representation of spectrum?
why is it used to describe lights instead of using spectrum to describe them?
lastly, is there any relation between CT and the actual temperature of the bulb? (by which i mean literally its heat energy, regardless of the spectrum)

i have tried googling about this but to no useful avail. if you KNOW about this please help me out here.
sorry if my questions seem basic, but different people seem to contradict eachother on info about this.
thank you for any help,
gimp.

shameless self bump

Hps have more lumens more heat, halide have less lumens less heat

bongwaterbob said:

Hps have more lumens more heat, halide have less lumens less heat

Click to expand...

completely irrelevant to what i am talking about

ok ill give this a shot for whtever it worth spectrum is your red r blue in ur lights kelvin measures the intensity of tht red r blue the higher the kelvins the brighter the color spectrum !

i think thts wht ur trying to figure out imo !

Color temperature goes back to the theory of radiating black bodies. Essentially, hotter = bluer. The sun has a blackbody radiation spectrum consistent with a temp of 5700 Kelvin. Incandescents are black bodies in the 2000s somewhere. If the emission spectrum follows the classic fourth-order blackbody emission curve, a color temperature can be accurately assigned. For spiky-spectrum sources like mercury lamps, the correlation becomes poor. For fluorescents, the spectrum diverges enough from the blackbody ideal that while statistics can be used to assign a "best fit" color temperature, it doesn't tell the story as well as for a thermal radiant source. cn

In simple terms, color temp is the average output across the entire spectrum, whereas the spectrum represents many different wavelengths throughout the spectrum of visable light. Color temp is somewhat irrelevant really. You could have two led lights, one emitting a cool light wavelength, and another emitting a warm wavelength. Combined, these two leds might have a color temp of 4000k however in reality their only emitting two very specific wavelengths, which would not be the same thing as a hps at 4000k.