  The OPERA experiment discovered muon neutrino into tau neutrino oscillations
in appearance mode, detecting tau leptons by means of nuclear emulsion films.
The apparatus was also endowed with electronic detectors with tracking
capability, such as scintillator strips and resistive plate chambers. Because
of its location, in the underground Gran Sasso laboratory, under 3800 m.w.e.,
the OPERA detector has also been used as an observatory for TeV muons produced
by cosmic rays in the atmosphere. In this paper the measurement of the single
muon flux modulation and of its correlation with the seasonal variation of the
atmospheric temperature are reported.
