Detailed characterization of an extrasolar planet's atmosphere provides the
best hope for distinguishing the makeup of its outer layers, and the only hope
for understanding the interplay between initial composition, chemistry,
dynamics & circulation, and disequilibrium processes. In recent years, some
areas have seen rapid progress while developments in others have come more
slowly and/or have been hotly contested. This article gives an observer's
perspective on the current understanding of extrasolar planet atmospheres prior
to the considerable advances expected from the next generation of observing
facilities. Atmospheric processes of both transiting and directly-imaged
planets are discussed, including molecular and atomic abundances, cloud
properties, thermal structure, and planetary energy budgets. In the future we
can expect a continuing and accelerating stream of new discoveries, which will
fuel the ongoing exoplanet revolution for many years to come.Comment: Accepted for publication. 18pp, 10 figures. v3: fixed more reference