  We present three terrestrial gamma ray flashes (TGFs) observed over the
Mediterranean basin by the Reuven Ramaty High Energy Solar Spectroscope Imager
(RHESSI) satellite. Since the occurrence of these events in the Mediterranean
region is quite rare, the characterisation of the events was optimised by
combining different approaches in order to better define the cloud of origin.
The TGFs on 7 November 2004 and 16 October 2006 came from clouds with cloud top
higher than 10-12 km where often a strong penetration into the stratosphere is
found. This kind of cloud is usually associated with heavy precipitation and
intense lightning activity. Nevertheless, the analysis of the cloud type based
on satellite retrievals shows that the TGF on 27 May 2004 was produced by an
unusual shallow convection. This result appears to be supported by the model
simulation of the particle distribution and phase in the upper troposphere. The
TGF on 7 November 2004 is among the brightest ever measured by RHESSI. The
analysis of the energy spectrum of this event is consistent with a production
altitude $\leq$12 km, which is in the upper part of the cloud, as found by the
meteorological analysis of the TGF-producing thunderstorm. This event must be
unusually bright at the source in order to produce such a strong signal in
RHESSI. We estimate that this TGF must contain $\sim$3x10$\rm ^{18}$ initial
photons with energy $>$1 MeV. This is 1 order of magnitude brighter than
earlier estimations of an average RHESSI TGF.
