AKICIF: green lights
Joy Beeson
Several years ago I noticed green yard lights. These lights have
gotten more and more common, and now some street lights are green.
The green lights look white when you get close enough to make them the
brightest thing in your field of vision, and flicker at the same rate
as sodium-vapor lights.
What kind of light fluoresces green?
--
Joy Beeson
joy beeson at comcast dot net
Dorothy J Heydt
Joy Beeson <jbe...@invalid.net.invalid> wrote:
>
>Several years ago I noticed green yard lights. These lights have
>gotten more and more common, and now some street lights are green.
>
>The green lights look white when you get close enough to make them the
>brightest thing in your field of vision, and flicker at the same rate
>as sodium-vapor lights.
>
>What kind of light fluoresces green?
Hal says, "It might be mercury vapor."
--
Dorothy J. Heydt
Vallejo, California
djheydt at hotmail dot com
Should you wish to email me, you'd better use the hotmail edress.
Kithrup is getting too damn much spam, even with the sysop's filters.
Paul Dormer
Heydt) wrote:
>
> >What kind of light fluoresces green?
>
> Hal says, "It might be mercury vapor."
I recall we had mercury vapour street lights in the town I grew up.
Don't recall them looking particularly green, more a bluish white.
Just seen the Jacques Tati film Playtime for the first time. There's a
scene in that set in a drugstore with a food counter. It's next to a
bright green illuminated pharmacy sign, which makes everyone have green
faces, and the food look distinctly odd.
Torbjorn Lindgren
>In article <KvnnB...@kithrup.com>, djh...@kithrup.com (Dorothy J
>Heydt) wrote:
>> >What kind of light fluoresces green?
>> Hal says, "It might be mercury vapor."
>
>I recall we had mercury vapour street lights in the town I grew up.
>Don't recall them looking particularly green, more a bluish white.
The Wikipedia article says they used to blueish, but that most modern
ones are "color corrected" which means they have a phosphor layer that
converts some portion of the ultraviolet emissions into red light.
Since it wouldn't have been visible anyway it probably don't hurt the
efficiency either.
That changes the spectrum significantly but they don't say what it
ends up as, it may well differ between manufacturers. There's at least
some mercury vapour lamp pictures in Google Images that seems to have
a greenish tint.
OTOH, it also mentions gradual bans on them, they seems to be on their
way out. The street lights are simple to understand (existing fixtures
getting new color corrected bulbs) but the other instances seems
stranger. Perhaps it's a different light source (multi-color LED or
phosphor white LED) with similar spectrum.
It also seems to be a pretty bad thing to use for street lighting,
given the described end-of-life failure mode (gradually reduced output, down to
zero but draws the same power and can't be detected as not working
other than by counting age or measuring light).
Back in the days there wasn't that many options but now there's so
many better ones already available, especially for new fixtures.
Keith F. Lynch
> Just seen the Jacques Tati film Playtime for the first time.
> There's a scene in that set in a drugstore with a food counter.
> It's next to a bright green illuminated pharmacy sign, which makes
> everyone have green faces, and the food look distinctly odd.
Film often misrepresents what color lights are. For instance ordinary
flourescent lights look greenish on typical color film, but don't look
greenish when seen directly.
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.
Paul Dormer
Lynch) wrote:
>
> Paul Dormer <p...@pauldormer.cix.co.uk> wrote:
> > Just seen the Jacques Tati film Playtime for the first time.
> > There's a scene in that set in a drugstore with a food counter.
> > It's next to a bright green illuminated pharmacy sign, which makes
> > everyone have green faces, and the food look distinctly odd.
>
> Film often misrepresents what color lights are. For instance ordinary
> flourescent lights look greenish on typical color film, but don't look
> greenish when seen directly.
Yes, but this is a comedy film, and the joke is that the food looks green
and unappetising. I suspect the print was treated to make everything
look more green.
Paul Dormer
Lindgren) wrote:
>
> It also seems to be a pretty bad thing to use for street lighting,
> given the described end-of-life failure mode (gradually reduced
> output, down to zero but draws the same power and can't be detected as
> not working other than by counting age or measuring light).
My mother always used to report faulty street lights, but she was a
councillor on the street lighting committee.