Simple clear blue summer sky:

The word inside a hemisphere of type "cheese cover" :
with a realistic fog at the horizon made by "color_map{gradient <0,1,0> ..." changing the color from white at the horizon level to deep blue at 12 am. All together blown up by "scale 10000" - the only problem:
You must keep the sun in this hemisphere, otherwise you see only the ambient component of all textures!

// sky ------------------------------------ sphere{<0,0,0>,1 hollow texture{ pigment{gradient <0,1,0> color_map{ [0.0 color White] [0.8 color rgb<0.1,0.25,0.75>] [1.0 color rgb<0.1,0.25,0.75>] } } // end pigment finish {ambient 1 diffuse 0} } // end of texture scale 10000 } // end of sphere -----------------------

You will get the same result without these limits by using "sky_sphere" with this "pigment".

Simple clear sky, type "cheese cover"
Description of this scenery for POV-Ray

sky_sphere{ pigment{ gradient <0,1,0> color_map{ [0.0 color rgb<1,1,1> ] [0.8 color rgb<0.1,0.25,0.75>] [1.0 color rgb<0.1,0.25,0.75>]} } // end pigment } // end of sky_sphere -----------------

Good clouds - bad horizon:

With the word inside a hemispere type "cheese cover" you should not change to a cloud texture because of the very unrealistic clouds crashing with the horizon!

Unfortunately also most cloudy skies created with "sky_sphere" are suffering from this illness!

bad sky: clouds crashing with horizon
Description of this scenery for POV-Ray

Partly cloudy sky with realistic horizon:

The sky is formed by a blue plane which is decorated by some clouds. The clouds become realisticly smaller at the horizon! This effect cannot be simulated by the use of "sky_sphere"! The realistic fog covers the black line at the horizon - the gap between the ground plane and the sky plane.
The only problem here:
You must keep the sun below this sky plane! - Otherwise you see only the ambient component of all textures!

partly cloudy sky - realistic horizon
Description of this scenery for POV-Ray

part I | part II | part III | part IV | part V | part VI | part VII | part VIII | part IX | part X