What is the primary function of an ambient air analyzer?

An ambient air analyzer primarily measures a gas's absorption of infrared radiation. This technology is crucial for assessing the concentration of various gases in the atmosphere, which includes evaluating pollutants and understanding atmospheric conditions.

Infrared absorption is a key principle utilized in many air quality monitoring devices. Each gas has specific absorption characteristics at different infrared wavelengths, which allows the analyzer to determine the amount of a particular gas present based on how much infrared radiation is absorbed. This capability is essential in environmental monitoring and compliance with air quality standards.

The other options pertain to different areas of analysis that an ambient air analyzer is not designed for. Temperature changes can be monitored by other types of sensors, soil composition is evaluated by soil testing methods, and water quality assessment would generally be conducted using separate water testing equipment. Thus, the correct answer aligns with the primary function of analyzing gases in the atmosphere, which is unique to the capabilities of an ambient air analyzer.