Adobe describes what Dehaze does: it “tries to estimate light that is lost due to absorption and scattering through the atmosphere”, Nifty. To me is Dehaze essentially is the same as Clarity, but with the masking applied automatically based on brightness and lack of contrast. What happens is that it compares each pixel to surrounding ones, not with the intent to find edges, but to exaggerate the difference in tone or hue. Where Dehaze is a bit different from Clarity is that Dehaze is limited to the brighter parts of the image. I guess the logic to it is, that lighter areas are where haze is a factor.
When Camera Raw introduced the Dehaze feature I was amazed and at the same time somewhat confused. For me it brought about a number of questions. I was pondering why Dehaze is down with the Effects sliders rather than up with the usual Exposure, Contrast and other “Basic” adjustments. I mean if Vibrance, Saturation and Clarity qualify, why not Dehaze? To this day I don’t know.
Dehaze effects the entire image, you cannot perform targeted adjustments with Dehaze, thus it’s not a life-threatening limitation, it is still an annoying limitation.