Slobodan: Your comments make sense to me. Indeed, the images to which I was referring were shot at 17mm. From the saturation of the sky (directly out of the camera), it appears that I was shooting with a polarizer.
It would be instructive for me to set up my tripod & shoot several images of the sky. First, shoot at various focal lengths without the polarizer. Second, at the lens' widest angle & with the polarizer attached, shoot several images varying the degree of polarization.