"Commander Kinsey" wrote in message
news
On Thu, 29 Aug 2019 01:31:58 +0100, Rod Speed
wrote:



"Commander Kinsey" wrote in message
news
On Wed, 28 Aug 2019 21:09:53 +0100, Rod Speed
wrote:



"Commander Kinsey" wrote in message
news On Wed, 28 Aug 2019 05:29:07 +0100, Rod Speed

wrote:



"Commander Kinsey" wrote in message
news On Tue, 27 Aug 2019 22:38:57 +0100, Max Demian

wrote:

On 27/08/2019 17:25, Commander Kinsey wrote:
On Tue, 27 Aug 2019 17:13:18 +0100, Colonel Edmund J. Burke
wrote:

On 8/27/2019 9:03 AM, Commander Kinsey wrote:
Why is hi-vis clothing easier to see? Whats so special about
the
colour?

Color, you ignorant limey.

So why isn't red, yellow, etc as easy to see? If you wear a
bright
red
tshirt, you aren't as visible as wearing a hi-vis jacket. Does it
convert all the wavelengths into one or something?

It's fluorescent. It converts ultraviolet (especially prevalent in
the
dusk) into visible light.

I never realised this - there's more UV at dusk?

Yep, because the sunlight is going thru a lot more air
and dust etc in the air and UV gets thru that better
than the longer wavelength light. Thats why sunsets
are red, the red light is reflected off the crap in the air.

Isn't it to do with diffraction and refraction?

Yes but thats just different words for the same thing.

No,

Yep.

No.

Yep

Diffraction is light encountering an obstacle, like the edge of a planet:
https://en.wikipedia.org/wiki/Diffraction

Thats just one form of diffraction.

Refraction is light encountering a different medium, like going from the
air into a lake: https://en.wikipedia.org/wiki/Refraction

Thats just one form or refraction.

one is bending round corners, eg long wave radio goes further as it can
go over mountains.

Thats not what is involved in there being more UV at sunset.

The other is bending when it goes into another medium, eg shining a
torch into water.

Thats not what is involved in there being more UV at sunset.

One bends high frequencies more, the other bends low frequencies more.

More UV at sunset isnt about bending.

You said above: "Thats why sunsets are red, the red light is reflected
off the crap in the air."

Because that is the reason for more UV at sunset.

But er.... we see sunsets as red, which means the red end of the spectrum
must be reaching our eyes more than the blue end.

Wrong, as always. We see sunsets as red because the sky
around the setting sun is red because of the red being
reflected off what is in the sky around the setting sun.

That doesnt happen with the UV as much so thats
why you end up with more UV at the observer at sunset.

Or just the same amount, and less visible light?

Less of the long wavelength red end of the spectrum, anyway.

Sunsets are orange.

Nope, red and red is adjacent to orange in the spectrum anyway.

Near enough. My point was there is more of the long wavelength end of
the
spectrum at sunset.

Not when talking about what ends up at the hi vis vest.

How would that be different from what ends up at your eye when looking at
a sunset?

It isnt, but thats not why sunsets look red, thats because
the red is coming from the sky around the setting sun.

You were incorrect!

Nope, I never am.

[falls off chair]

Get a higher chair so you fall on your head next time.

I guess it's to do with diffraction of sunlight at the horizon?

More the much longer amount of air in the path between
the sun and you.

Presumably mainly available in certain colours.

Why are they always yellow or green?

They arent normally green and plenty are orange/reddish.

Almost every one I see nowadays is yellow.

Then you need to get out more.

I have no desire to see more health and softy bull****.

It isnt H&S bull****.

That's what hivis is all about - ****ing safety.

Its also about who works for the railways
etc with the different color for them etc.

Same with the cops and paramedics and fireys
etc at car crashes etc, helps to be able to see
who is who quickly at the scene.

A google image search shows 75% yellow and 25% orange,

Its nothing like a representative sample of whats seen in the real
world.

A google search is very representative.

Google image results arent.

Same coding.

Nope.

although I can't remember the last time I saw an orange.

Then you need to get out more. It varys by industry too. some
like the railways have their own colors for various reasons.

Ah, I do remember orange at a level crossing.

Yeah, thats the most obvious example.

Why do railways need different colours?

So they can easily work out who does what job etc.