  A large cloud of $^{87}$Rb atoms confined in a magneto-optical trap exhibits,
in a certain regime of parameters, spatio-temporal instabilities with a
dynamics resembling that of a turbulent fluid. We apply the methods of
turbulence theory based on structure function analysis to extract scaling
exponents which are compared to known turbulent regimes. This analysis also
allows us to make a clear distinction between different instability regimes.
