load different images into page every time the website is viewed?
Write an onload= function to set the src= field of the IMG(s).
You can use Math.random() to compute filenames based on a pattern (cloud0.jpg, cloud22.jpg, cloud7.jpg, etc.) or choose arbitrary filenames from an array ["sky.jpg","cloud.gif","rain.bmp","snow.jpg"] .
To change the IMG(s) in a predictable (instead of random) way, you could use something like [a part of] the day or time.