  We compare the spectral properties of long meteorological temperature records
with laboratory measurements in small convection cells. Surprisingly, the
atmospheric boundary layer sampled on a daily scale shares the statistical
properties of temperature fluctuations in small-scale experiments. This fact
can be explained by the hydrodynamical similarity between these seemingly very
different systems. The results suggest that the dynamics of daily temperature
fluctuations is determined by the soft turbulent state of the atmospheric
boundary layer in continental climate.
