  Rayleigh Brillouin (RB) scattering profiles for air have been recorded for
the temperature range from 255 to 340 K and the pressure range from 640 to 3300
mbar, covering the conditions relevant for the Earth's atmosphere and for
planned atmospheric light detection and ranging (LIDAR) missions. The
measurements performed at a wavelength of 366.8 nm detect spontaneous RB
scattering at a 90 degree scattering angle from a sensitive intracavity setup,
delivering scattering profiles at a 1 percent rms noise level or better. The
elusive transport coefficient, the bulk viscosity, is effectively derived by a
comparing the measurements to the model, yielding an increased trend. The
calculated (Tenti S6) line shapes are consistent with experimental data at the
level of 2 percent, meeting the requirements for the future RB scattering LIDAR
missions in the Earth's atmosphere. However, the systematic 2 percent deviation
may imply that the model has a limit to describe the finest details of RB
scattering in air. Finally, it is demonstrated that the RB scattering data in
combination with the Tenti S6 model can be used to retrieve the actual gas
temperatures.
