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We present a highly accurate Raman spectrometer capable of measuring changes in atmospheric temperature as small as 0.75 K with high spatial and temporal resolution. The spectrometer is based on a laser diode tuned to the resonant absorption line of the${}^{85}\mathrm{R}\mathrm{b}$isotope near 780.0 nm. A heated glass cell containing Rb atoms was used as an ultranarrowband atomic absorption notch filter with$0.3\mathrm{c}{\mathrm{m}}^{-<\#comment/>1}$bandwidth and optical density as high as four. This filter was placed in front of the spectrograph and blocked up to 99.99% of the elastically scattered laser light, which made it possible to resolve the pure-rotational Raman spectra of molecular atmospheric gases. The relative intensities of pure-rotational Raman transitions were then used to infer atmospheric temperature changes.

A new instrument was designed and developed to map the spatial distribution of water vapor concentration in the atmosphere. The high spatial resolution, sensitivity, and accuracy of the instrument enable new studies of the role of turbulence on clouds and aerosols in small-scale laboratory environments. The instrument exploits Raman scattering in a multi-pass laser configuration by using a set of narrow bandpass filters and a pair of charge coupled device imaging cameras in the 90° scattering geometry. The absolute concentration of water vapor was inferred from measured ratios of H₂O and N₂vibrational Raman transitions. We have measured the number densities of water molecules in the atmosphere as low as 3.5 × 10¹⁷cm^−3,with an accuracy better than 20% and as high as 7.0 × 10¹⁷cm⁻³during minutes long observations. These measurements were taken within an imaging region 6 cm in diameter, with a per-pixel resolution 2.60 mm wide by 0.16 mm tall and 1 mm deep.