Short answers, pulled from the story.
Adiabatic cooling occurs when rising air expands and loses heat. Conductive cooling happens as air touches colder surfaces like land or water. Radiational cooling results from infrared emission by the air itself. Evaporative cooling forces temperature down as moisture enters the air mass.
Cherrapunji in India holds the record for confirmed wettest place with an average annual rainfall of 11,872 millimeters. Mawsynram nearby averages 11,871 millimeters over thirty-eight years. Lloró in Colombia likely receives the largest rainfall globally at an estimated 13,300 millimeters per year.
Rainfall chances peak by Saturday after five days of weekday pollution build up in heavily populated coastal cities. Rainfall rates downwind of cities increased between 48 percent and 116 percent due to this effect. Heavy downpours have increased significantly across the United States since 1950.
Meteorologists measure rainfall using standard gauges with inner and outer cylinders for accuracy. Tipping bucket rain gauges and weighing rain gauges provide alternative measurement methods. Weather radar estimates precipitation over large basins for hydrological purposes like flood control.
Tropical rainforests exist along the equator within ten degrees latitude maintaining high humidity year-round. Temperate rainforests are located further from the equator but still possess high rainfall levels. Dry rainforests maintain dense canopies despite facing periodic drought conditions.