Measurements of the fall-velocity of water -drops and raindrops

This paper presents measurements of the velocities of water-drops of sizes ranging from one to six mm in diameter, falling in still air from heights of 0.5 meter to 20 meters. A few measurements of raindrop velocities are also reported. The measurements were undertaken to assist in an understanding of the action of rain, both real and artificial, in eroding soil. The drop-sizes of rains have also been measured and will be reported separately. All of these studies were carried out at the Hydraulic Laboratory of the National Bureau of Standards as a part of the work of the Soil Conservation Service.