I, personally, like bright skies for my backgrounds!  Having one to fly around in, is equally exciting!  It just happening to make for highly detailed chrome renders is a sidekick, but Poser reflections are really tough, because Poser doesn't have the sense enough to apply the Background Color/image to Raytraced Reflections.?  The only way for Reflective Materials to actually reflect things and be shiny; is to either use reflection map(that always needs to be updated when you add/move things within your scene,) ...or just have actually shaded geometry; actually protecting Firefly, from the void Poser Scene Space ends in.

"I'm not sure what you're trying to do here."

Trying to keep a perfect sphere, after Normal Reverse.  After I Reversed Normals, the Ball Hi-Res prop Deformed?
And see that weird Window looking artifact, on the right side of the front surface(like a bout nine square panes stack in a square?)  That is no object in my scene, I can't imagine where they are coming from?

"You see, to me a sky dome should not be shaded with light-sensitive features like an ordinary object.

When the Normal geometry is Reversed the Diffuses Color > Image_Map is applied to the inside, where it can play well with what needs reflecting with within the scene, and light is allowed to pass through from the outside in.  

"IT IS THE SOURCE OF THE ILLUMINATION"

...Maybe, soon, I'll look to develop a White Glow material to apply on a single Sky Dome; that would make for an interesting Global Illumination effect, and I could try it on a 2nd Skin figure. 
Currently I'm using Infinite lights.  My sky doesn't actually Figure lighting much at all, the amount is not noticeable. With the sky dome Visible, or without, my V3 figure renders as her best.  The Scale of the Sky Dome only effects the brightness if reflections, the bigger the dome the brighter they get.

"Now if you want to use concentric spheres, and transparency, so you can build up layers of clouds, that's fine. Me - I just blend them in the shader directly and have only one sky sphere to manage at all times."

I'm sure you could keep things nice and simple, until the cows come home, BB...I'd hoped the 3D Textures > Clouds node would effect the entirety of the inside of my Ball HiRes prop, and have tried to use Displacement, but it looks like we're only working with the surface?  Can the interior of my Ball Hi-Res prop be MAT'd as well?  Meanwhile I'm still waiting on more Cloud nodes(and/or materials,) and my reason for multiple Transparent Cloud Domes/Layers is eventually postion them at respective Altitudes.

"There is no "specular reflection" off the sky - there is no reflection on the sky"

Ah, The Specular value adds whiteness to the clouds, without any ill effect; although removing that causes the clouds to bleach fast, so I let it be.

"Theoretically, using multiple sky spheres could let you get some "real world" effects like shadows from one cloud layer falling on the next. In such cases, I'd still set up the "sky" sphere to glow. The "cloud" spheres could then be using Diffuse and Specular effects in the shader. Moving the sun around would produce a different sky then..."

Thank you!

"I'm not sure if Poser can handle the scaling though that would lead to real-life perspective."

Hmm, me neither.  I switched Measure from Poser Native Units, to Feet, but Parameter > Scale > Value didn't change?

"Assume your clouds are 1 mile high. The radius of a Poser sphere at 100% scale is 5.16 inches. So the scale you need to set to get the radius to be one mile is 100 * 5280 * 12 / 5.16 which is 1,227,907. IIRC, last time I tried a sphere scaled to over a million percent, it didn't render in the reflections at all - it's like it was too far away to be seen."

Ouh, that was cool!  I could live with a cloud layers about 3/4 a mi.  I see what you're saying about scale over 1,000,000; I tried export/importing the Ball UV, easier I knew the Scale Parameter would reset, but it imported at it's original scale?

"Oh and the Poser sphere surely has issues with normals and also its UV map is not right. There is always a seam. I found it better to go into some other tool and generate a new sphere of my own, and imported that. I've had no issues since then."

and

"If your having problems with poser hires ball. I could send you my sky dome prop from lightwave."

Great things to know!  How many polygons are we talking, I'm thinking DAZ Figure Weight.  V3 is pretty heavy, she's about 72,000 polygons; but M2 is much lighter, at about 32, 000.  I suspect anything under 15,000 would'nt be worth testing?

"Also, how about particles for clouds, that way you could animate them."

Particles sound awsome, do you know of any good examples?  I've only seen Poser particles for sale, but haven't purchased any yet.