Every morning at seven, Andrew Welch wakes up, cooks breakfast and checks the rain gauge sitting on a five-foot post in his backyard. He writes down the measurement, sends his kid off to school and then heads out to his workplace as a structural engineer. Welch is a citizen scientist. Around the world, hundreds of citizen scientists like him are collecting precipitation measurements from the ground that are useful for NASA’s Global Precipitation Measurement (GPM) mission. CoCoRaHS volunteers stand with Dr. Walt Petersen, far left, Dr. Jackson Tan, third from right, and Dr. Tiffany Moisan, far...