Outer Atmospheres of Late-Type Stars

I will attempt to summarize our limited understanding of the outer atmospheres of red giants by describing recent important observational results concerning chromospheres and coronae in late-type stars and how red giants fit into the emerging picture. In particular, I will point out where in the cool half of the HR diagram chromospheres, transition regions, coronae, and large mass loss occur and suggest what the important parameters determining the energy balance of these layers might be. I will then summarize the chromospheric modelling process and describe in detail models of the late-type supergiants $\beta$ Dra (G2 II), $\epsilon$ Gem (G8 lb), and a Ori (M2 lab) recently computed by Basri and Linsky.