The measurements were taken in the upper part of the ESO 3.6-m dome
(fig. 
), taking
advantage of the bridge crane there located, during the
evening of a windy day when the dome anemometer indicated almost
constantly a mean velocity of 18 m/s from North.
The dome slit was entirely opened.
A vortex type anemometer (fig. ) was utilized, which
is particularly suited for fast response
measurements, having a 
resolution of 6 mm.
The measurements consisted of wind velocity sequences of 137 seconds
each with 4096 records, therefore at the frequency of nearly 30 Hz.
Several such sequences were recorded at different positions along the
path of the bridge crane as shown in fig. .
Before each sequence, the dome was rotated forth and back
in order to find, rather empirically, the azimuth angle at which one
would have the stronger feeling of wind flow and turbulence. Not
surprisingly, this was found to be approximately facing the mean wind
direction. Therefore the values measured are properly worst case
quantities, as one may expect that during observation the slit would be
facing the wind only a fraction of the observing time.