Measurement of the rayleigh scattering properties of some gases with a nephelometer.
Nephelometers used in NOAA's Geophysical Monitoring for Climatic Change program are very sensitive instruments for measuring the scattering extinction coefficients of aerosols and gases. These instruments are calibrated by filling them with gases having known scattering coefficients, such as air, carbon dioxide, and dichlorodifluoromethane (CCl(2)F(2)). Because of its sensitivity, the nephelometer can be used to study the scattering properties of these gases. In these experiments the volume Rayleigh scattering of CCl(2)F(2) was found to be 15.3 times that of air, and the volume scattering of argon was found to be 0.879 times that of air. Furthermore, the index of refraction of argon has been deduced from these measurements and is in excellent agreement with published values. A new depolarization factor of CCl(2)F(2) deduced from these measurements is 0.048.