  Ubiquitous in nature, convection cells are a clear signature of systems
out-of-equilibrium. Typically, they are driven by external forces, like gravity
(in combination with temperature gradients) or shear. In this article, we show
the existence of such cells in possibly the simplest system, one that involves
only a temperature gradient. In particular, we consider an Ising lattice gas on
a square lattice, in contact with two thermal reservoirs, one at infinite
temperature and another at $T$. When this system settles into a non-equilibrium
stationary state, many interesting phenomena exist. One of these is the
emergence of convection cells, driven by spontaneous symmetry breaking when $T$
is set below the critical temperature.
