If this won't cure my SAD, what will?

[fivemack]

This is the 85W-from-socket 425W-incandescent-equivalent-power lightbulb that I bought to see whether it would make me happy.

For size comparisons, that is an Apple smallish keyboard, a real apple and a real kiwifruit. The fruit are normal-sized examples of their ilk, and the bayonet on the lamp is of the standard size.

Comments

[jiggery-pokery.livejournal.com]

I have some ignorant questions and you (pl.) are not just smart, but also likely to enjoy talking about this and likely to give a more human-focused response than web sites I might encounter by JFingGingI.

Can you reliably tell what colour the light from a light bulb will be just by the temperature to which it is rated? (I have a suspicion that the temperature is assessed by measuring the colour of the light, so the answer ought to be yes, but this is why I add the "reliably" qualification.)

What temperature light is emitted by traditional incandescent light bulbs? Does the colour of the glass around the filament have an impact on this? If we were to buy a fluorescent of equivalent temperature to a traditional incandescent, would we expect the lighting characteristics produced to be the same in practice, or are there other ways in which fluorescent and incandescent bulbs' lights differ from each other? (Assume I am not using dimmer switches and do not get headaches from fluorescents.)

[del-c.livejournal.com]

Those of us who enjoy space opera know the factoid about how a "red" sun would look just like a 100W bulb, because tungsten bulbs are actually very red. That says humans can't really tell temperature by looking at a grey emitter. We particularly can't tell whether we're looking at a grey emitter or something that just mimics one in a few wavelengths, which is why fluorescent tubes look white-hot even though they aren't melting the kitchen ceiling.

[htfb.livejournal.com]

That depends on how bad the chromatic aberration of your spectacles is.

[fivemack.livejournal.com]

My suspicion is that the colour temperature is written on the pots that the phosphor comes in, and carefully transcribed by someone at the bulb factory. Using an improvised spectroscope made out of a David Attenborough DVD and the corner of an envelope, it's clear that this particular bulb is emitting in about five fairly sharp lines: bright green and red, a fainter yellow, somewhere cyan-ish a bit fainter than the yellow, and faintly somewhere in the deep blue.

Traditional incandescent light bulbs are somewhere between 2000 and 3300K, halogen ones are a bit higher brightness. Peak lambda is inversely proportional to temperature and something like 2.9mm / (temperature in kelvin) so is somewhere in the IR for all incandescents.

If the filament is behind coloured glass, its spectrum will be very non-black-body and I'm not sure how the colour temperature is then defined - for instance, at no temperature will an incandescent object look apple-green, the spectrum's just too broad.