Three daytime flights of the UK Meteorological Office's C-130 aircraft
through thick frontal cirrus have been analysed with the aim of deter
mining the length scales at which energy is produced, and which mechan
isms are responsible. The data was obtained as part of the EUCREX camp
aign. It will be shown that the occurrence of turbulence is patchy, we
ak and rather 2-dimensional with most turbulent kinetic energy being c
ontained in the horizontal wind components. Evidence for the productio
n of turbulence by the breaking of Kelvin-Helmholtz waves is found for
all of the flights analysed. In one case there also seems to be turbu
lence production at a scale of 2 km by convection set up by radiative
cloud top cooling.