  We find that the conditional statistics of temperature difference at fixed
values of the locally averaged temperature dissipation rate in turbulent
convection become Gaussian in the regime where the mixing dynamics is expected
to be driven by buoyancy. Hence, intermittency of the temperature fluctuations
in this buoyancy-driven regime can be solely attributed to the variation of the
locally averaged temperature dissipation rate. We further obtain the functional
behavior of these conditional temperature structure functions. This functional
form demonstrates explicitly the failure of dimensional agruments and enhances
the understanding of the temperature structure functions.
