Take the following two pictures:

Unprocessed Image

Processed

The thing that should jump out at you in the “before” picture is that the clouds have virtually no definition and the sky is washed out.  They are drastically overexposed due to the dark foreground.  Now, some of this may be due to the altitude – I was about 8,000 feet above sea level, something I’m not too used to.  So my mental focus wasn’t that sharp, and I didn’t review the histogram on-site for blown-out highlights.

ACR Settings used for resurrecting and finalizing this photo - click for larger

Move your mouse over the two pictures.  See the red that shows up there?  That’s where there is no detail – in the JPEG-saved version, at least.  The first photo is as it came out of the camera.  The second has just a minor tweak in Adobe Camera RAW to drop exposure by just under a stop.  See how much detail returned in the clouds?

This is because this was a RAW photo – and that means that highlights aren’t actually blown out.  They certainly are if it’s a two or more stops past the exposure of the photo, but if it’s less?  Detail is still there, as shown by the second photo.

An overview of the settings used to resurrect this photo are to the right.  You’re now seeing an underexposed foreground, but properly exposed clouds.  Bringing back up some of those shadows and you end up with as much detail as you could ever want in a photo like this:

The final version