Abstract

The characteristics of polarimetric weather radar measurements depend on the physical (e.g., size, shape, and orientation), statistical (e.g., the distribution of sizes and orientations), and electromagnetic (EM) properties (e.g., dielectric constant and conductivity that cause wave scattering) of water particles (raindrops, snowflakes, hailstones, cloud droplets, and ice crystals), as well as other objects (aerosols, insects, birds, etc.) that might be in the radar resolution volume through the main lobe or sidelobes. To correctly relate polarimetric radar echo characteristics to the hydrometeors within the resolution volume, it is necessary to understand cloud/precipitation physics and polarimetric radar measurements. In this chapter, we provide the physical, statistical, and electrical descriptions of raindrops, snowflakes, hailstones, and cloud particles.