Two flights of the UK Meteorological Office's Hercules aircraft throug
h daytime frontal cirrus around Scotland have been analysed using wave
let analysis on the vertical velocity time-series from the horizontal
runs. It is shown that wavelet analysis is a useful tool for analysing
the turbulence data ill cirrus clouds. It finds the largest scales in
volved in producing turbulence, as does Fourier analysis, such as the
2-km spectral peaks corresponding to convective activity during flight
A283. Wavelet spectra have the added advantage that the position is s
hown, and so they identify smaller-scale, highly localised processes s
uch as the production of turbulent kinetic energy by the breaking of K
elvin-Helmholtz waves due to the vertical shear in the horizontal wind
. These may be lost in Fourier spectra obtained for long time-series,
though they contribute something to the average spectral density at th
e appropriate scale. The main disadvantage of this technique is that o
nly octave frequency bands are resolved.