  Next-generation space telescopes will observe the atmospheres of rocky
planets orbiting nearby M-dwarfs. Understanding these observations will require
well-developed theory in addition to numerical simulations. Here we present
theoretical models for the temperature structure and atmospheric circulation of
dry, tidally locked rocky exoplanets with grey radiative transfer and test them
using a general circulation model (GCM). First, we develop a
radiative-convective model that captures surface temperatures of slowly
rotating and cool atmospheres. Second, we show that the atmospheric circulation
acts as a global heat engine, which places strong constraints on large-scale
wind speeds. Third, we develop a radiative-convective-subsiding model which
extends our radiative-convective model to hot and thin atmospheres. We find
that rocky planets develop large day-night temperature gradients at a ratio of
wave-to-radiative timescales up to two orders of magnitude smaller than the
value suggested by work on hot Jupiters. The small ratio is due to the heat
engine inefficiency and asymmetry between updrafts and subsidence in convecting
atmospheres. Fourth, we show using GCM simulations that rotation only has a
strong effect on temperature structure if the atmosphere is hot or thin. Our
models let us map out atmospheric scenarios for planets such as GJ 1132b and
show how thermal phase curves could constrain them. Measuring phase curves of
short-period planets will require similar amounts of time on the James Webb
Space Telescope as detecting molecules via transit spectroscopy, so future
observations should pursue both techniques.
