When did our primary airspeed indications (that is, those used by general aviation) go from reading in miles per hour to being given instead in terms of knots?
Galileo notwithstanding, with raindrops, the bigger they are, the faster they fall. (For objects of that size, the surface area to volume ratio dictates the extent to which it will overcome air resistance and viscous drag as it falls. Larger drops have a greater terminal velocity.) But when a raindrop falls faster than about 18 miles per hour (in still air) what will usually happen?