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The paper considers the problems of laser applications and laser equipment developed to investigate the vibration-rotation absorption spectra of atmospheric molecular gases as well as the measurements of their concentration in the field conditions based on researches carried out at the Institute of Atmospheric Optics SB USSR Academy of Sciences. High resolution laser spectrometers, including intracavity laser spectrometers, laser spectrophotometers, opto-acoustic laser spectrometers, fluorescence laser spectrometer are described. Using these spectrometers, some thousands of new absorption lines, tens of previously unknown $H2O,CO2,C2H2,N2O,NH3,CH4$, HBr molecular absorption bands and their isotopes were recordered, assigned and analyzed, various molecular interactions were studied. The quantitative spectroscopic data obtained were widely used for laser gas analysis of the atmosphere, for determining concentrations of different atmospheric gases and, especially, of water vapor and of atmospheric pollutants. A new approach to the development of the differential technique in the trace gas analyzers is discussed.