Abstract: Methods and apparatus for classifying and/or discriminating particles in an aerosol. An example method involves delivering a flow of the aerosol through a nozzle into a sampling volume and directing a plurality of light beams onto an interaction plane in the sampling volume. The plurality of light beams may each be made up of light having one of a corresponding plurality of different wavelengths. For example, the wavelengths may include wavelengths of visible and infrared light or visible, near infrared and short wave infrared light. The method may detect intensities of light from the plurality of light beams that has been scattered at the interaction plane by particles of the aerosol at a plurality of different scattering angles. The resulting data is processed to characterize and/or discriminate the particles.