Water droplets scattering

The observation may be by a lamp illuminating the surface and a photocell to detect the scattered light due to the water droplets on the surface. The accurate measurement of the surface temperature, which is the dewpoint temperature, is critical. If a coolant is used, a close approximation for the surface temperature is the fluid temperature otherwise a small thermocouple or resistance sensor can be attached to or embedded into the surface. 

Light is scattered all around us— the fact that the sky above us appears blue, the clouds white, and the sunset shades of reds and oranges is a consequence of preferential scattering of light from air molecules, water droplets, and dust particles. This scattered light carries messages about the scattering objects. 

FIGURE 9.19 Mie intensity parameters versus scattering angle for water droplets (m f.333) having a 0.8, 2.0, and 10.0. Solid... 

FIGURE 9.20 Relative scattering Mie intensity parameter (i, ( ll) versus size parameter for water droplets (m 1.33) at scattering angles of 30° and 90° (adapted from Hinds, f982). 

Table 4.1 Scattering Coefficients for a Water Droplet in Air with Size Parameter x = 3 and Complex Refractive Index m = 1.33 + 10 8...

Ripple structure was observed in scattering at 90° by water droplets as they nucleated and grew in a cloud chamber (Dobbins and Eklund, 1977). We shall show in Section 11.7 that ripple structure is easily observed in extinction by... 

Sassen, K., and K. N. Liou, 1979. Scattering of polarized laser light by water droplet, mixed-phase and ice crystal clouds Part I. Angular scattering patterns, J. Atmos. Sci., 36, 838-852. 

Saunders, M. J., 1980. The effect of an electric field on the backscattered radiance of a single water droplet, in Light Scattering by Irregularly Shaped Particles, D. Schuerman (Ed.), Plenum, New York, pp. 237-242. 

This formulation presents a thin barrier between the water vapor (i.e., fog, steam, etc.) and the glass which will prevent fogging. The ability to lower the surface tension of the water prevents the clinging of individual water droplets to the glass therefore light is not scattered as much as it is when passing through individual droplets. 

For water droplets (m = 1.33), a plot of Qext versus a is shown in Fig. 16.3. Oscillations in the value of Qext are due to internally reflected light being in or out of phase during scattering. Also shown is a plot for a material having the same real refractive index as water but a small and intermediate absorption component (m = 1.33 - O.Oli and m = 1.33 - O.lz). The effect of absorption on oscillations in Qext as the absorption component increases can be clearly seen. 

Babick et.al. [261] compare sound spectroscopic determination of particle size distributions of sub-micron emulsions with dynamic light scattering and laser diffraction using olive oil in water droplet suspensions at volume concentrations from 1% to 60%. 

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