Editing Backscatter (section)

=== Radar, especially weather radar ===
Backscattering is the principle behind [[radar]] systems. In [[weather radar]], backscattering is proportional to the 6th power of the diameter of the target multiplied by its inherent reflective properties, provided the wavelength is larger than the particle diameter ([[Rayleigh scattering]]). Water is almost 4 times more reflective than ice but droplets are much smaller than snow flakes or hail stones. So the backscattering is dependent on a mix of these two factors. The strongest backscatter comes from [[hail]] and large [[graupel]] ([[solid]] [[ice]]) due to their sizes, but non-Rayleigh ([[Mie scattering]]) effects can confuse interpretation. Another strong return is from melting [[snow]] or wet [[Rain and snow mixed|sleet]], as they combine size and water reflectivity. They often show up as much higher [[Rate (mathematics)|rates]] of [[precipitation (meteorology)|precipitation]] than actually occurring in what is called a ''[[Weather radar#Bright band|brightband]].'' [[Rain]] is a moderate backscatter, being stronger with large drops (such as from a [[thunderstorm]]) and much weaker with small [[droplet]]s (such as [[mist]] or [[drizzle]]). [[Snow]] has rather weak backscatter. Dual polarization weather radars measure backscatter at horizontal and vertical polarizations to infer shape information from the ratio of the vertical and horizontal signals.