"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? What’s 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. That’s 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 that’s just different words for the same thing.

No,

Yep.

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

That’s 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.

That’s 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.

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.

You were incorrect!

Nope, I never am.

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****.

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.

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, that’s the most obvious example.

Just to do with the chemicals in the dyes that can convert UV into
visible?

To some extent.

Some, intended to be used at night, have strips that include glass or
plastic beads that reflect light (from torches or car headlamps) back
in
the direction the light source is.

I once saw somebody being quite ingenious. He'd broken down
and had no available light source from the vehicle (dead electrics
presumably, no hazard lights etc). He'd put two hi vis jackets on the
back, and every time a car approached, he flashed his torch at them.

Why wasn’t the other car headlights on the hi vis jackets enough ?

Because they weren't shining directly towards them. It was certainly
working, I could seer the jackets 5 or 10 times brighter when he used
the
torch.