Re:Chicago's About to Get a Lot Less Orange
by f_allwein on Friday April 21, 2017 @08:28PM
(#14170477)
Light pollution is another important side aspect of this. What if, as light becomes cheaper, people/ cities just use more of it? From other comments, it sounds like this is already happening with LED.
[ Parent
| on HN ]
LED will pretty much be better in terms of light pollution. With tubes or filaments, you need to make expensive reflectors to prevent the light going in directions you don't want.
LED lighting is much easier to make directional. With LED lighting, the difficulty is making it more isotropic.
Re:Chicago's About to Get a Lot Less Orange
by colanderman on Saturday April 22, 2017 @12:18AM
(#14171094)
Sodium lights are trivial to block using optical filters. This is very common in astronomy.
LEDs + phosphor, not so much, due to their wider spectrum. That less is emitted directly skyward doesn't help if what's reflected off pavement can't be filtered out. (Pavement is surprisingly reflective even though it's "black".)
The main issue I've heard about is that LEDs are generally more wide-spectrum than sodium vapor lamps. This leads to a lot more sky glow (light pollution). There's a good webpage about this here: http://www.flagstaffdarkskies.org/for-wonks/lamp-spectrum-li...