Help choosing RGB LED

[Benm]

And the difference between 30,000k and infinity Kelvin would be nearly zero.

That is because people misquote color temperature.

It should the 'spectrum emitted by a blackbody at that temperature', which is fairly accurate from tungsten lamps and 2700K or halogens running closer to 3000K.

This assumption that usable visible light would be emitted when the temperature approaches infinity is nonsense. If you ram up the blackbody temperature to a million or billion kelvin it will still radiate, but with most of the 'light' coming out in the UV and beyond - excellent to set your room on fire, not so good for reading a book by.

As for actual sunlight: in space that is in the order of 6000K, but since some of the blue is scattered in the atmosphere on the ground it's more like 4000K during daytime, rolling down to 2000K or less at sunset depeding on distance to the horizon.

 

[LuxorLasers147]

Ended up learning quite a bit about LED light. Thank you all for the input!

 

[Cyparagon]

As for actual sunlight: in space that is in the order of 6000K, but since some of the blue is scattered in the atmosphere on the ground it's more like 4000K during daytime

Uh, maybe if you ignore the light contributed by the rest of the sky. But I'm not sure why you would do that.

 

[Encap]

The Commission Internationale de l'Eclairage (CIE) measured the color of daylight in Washington D.C. at noon on the vernal equinox in 1931.
The daylight color was the same color of a block of tungsten heated to 4,870°K.
The 4,870°K temperature was rounded to 5,000°K.
The CIE then developed a color temperature scale based on this intersection of the color of daylight and the color of a heated tungsten block

Noon summer sunny daylight is between 5500K and 6000K depending on latitude and climate

 

[Cyparagon]

a block of tungsten heated to 4,870°K.

Considering tungsten melts at 3695 kelvin, that's quite impressive.

 

[diachi]

Considering tungsten melts at 3695 kelvin, that's quite impressive.

Puddle of tungsten.*

 

[Benm]

Uh, maybe if you ignore the light contributed by the rest of the sky. But I'm not sure why you would do that.

You would do that if the sun was shining through your window, but that window is of finite size so it would not let all the scattered light through.

But more generally: the scattering is in all directions, including ones that do not even make it to the earth surface (i.e. into space).

What the remainder that makes it to the ground is differs by location obviously. If you have the least possible amount of atmosphere between the sun and the ground (say on the equator on march 20 or so) it would be a higher color temperature compared to what we get in "western" countries that are so far north that they never get the sun directly above them.

A straight overhead sun is not possible in mainland US or europe, although the most southern tip of florida does get pretty close. It is possible from say cuba or mexico city, and as far as the US terriroty goes Hawaii, and most certainly Guam.


If you find youself in a place with the sun directly overhead it's actually a pretty strange experience since things cast no shadows sideways. This is demonstrated easily by sticking a pole in a beach or such, more much more creepy in every day situations when a can of soda just doesn't have any shadow at all.

 

[angelsnow]

Yes, LED strips can light up a room. Just choose the good shade. Maybe a 7.5 watt (RGB).