  Atmospheric wind speeds and their fluctuations at different locations
(onshore and offshore) are examined. One of the most striking features is the
marked intermittency of probability density functions (PDF) of velocity
differences -- no matter what location is considered. The shape of these PDFs
is found to be robust over a wide range of scales which seems to contradict the
mathematical concept of stability where a Gaussian distribution should be the
limiting one. Motivated by the instationarity of atmospheric winds it is shown
that the intermittent distributions can be understood as a superposition of
different subsets of isotropic turbulence. Thus we suggest a simple stochastic
model to reproduce the measured statistics of wind speed fluctuations.
