Community Collaborative Rain, Hail and Snow Network Canadian provinces of Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, Quebec, and Saskatchewan. There were over 20,000 participants as of March 2015. Community Collaborative Rain, Hail and Snow Network The Community Collaborative Rain, Hail and Snow Network, or CoCoRaHS, is a network of volunteer weather observers in the United States, Canada, and the Bahamas that take daily readings of precipitation and report them to a central data store over the internet. The network was started in 1997, in Larimer County, Colorado after a flash flood in Spring Creek killed five people and
Backscatter 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 sleet, as they combine size and water reflectivity. They often show up as much higher