  The atmosphere gains available potential energy by solar radiation and
dissipates kinetic energy mainly in the atmospheric boundary layer. We analyze
the fluctuations of the global mean energy cycle defined by Lorenz (1955) in a
simulation with a simplified hydrostatic model. The energy current densities
are well approximated by the generalized Gumbel distribution (Bramwell,
Holdsworth and Pinton, 1998) and the Generalized Extreme Value (GEV)
distribution. In an attempt to assess the fluctuation relation of Evans, Cohen,
and Morriss (1993) we define entropy production by the injected power and use
the GEV location parameter as a reference state. The fluctuation ratio reveals
a linear behavior in a finite range.
