A little tip for photographing a scene that has a lot of white:
Push the whites to the right.This is in reference to your histogram. Be sure your camera's histogram graph shows that the whites (which on a largely white landscape will be the spike of pixels towered high on your graph) are as far to the right of the graph as possible without going over. Adjust your aperture or shutter speed to accomplish this.
Often we'd like to see the bulk of the pixels right in the middle of the graph. This is not so with a bright white image. If you leave the camera to decide this on its own, you will find that your whites are grey, not bright and clean. Try this tip and see the difference for yourself.