I shot the third image at 12:29 PM according to my camera. Again, I used f8 and ISO 100. The exposure time was 1/160sec. What happened? Normally you would expect an exposure time of at least 1/250 which I had at 9:00 AM. The answer is pretty simple. There were a few clouds around blocking the direct sunlight and acting like a large softbox. If you compare the first three images you will find that this one is the softest of all images.
Enjoy and happy photographing!