5 months ago
Last edited at 4:44AM on 11/23/2013
"Small raindrops (radius < 1 millimeter (mm)) are spherical; larger ones assume a shape more like that of a hamburger bun. When they get larger than a radius of about 4.5 mm they rapidly become distorted into a shape rather like a parachute with a tube of water around the base --- and then they break up into smaller drops."
"This remarkable evolution results from a tug-of-war between two forces: the surface tension of the water and the pressure of the air pushing up against the bottom of the drop as it falls. When the drop is small, surface tension wins and pulls the drop into a spherical shape. With increasing size, the fall velocity increases and the pressure on the bottom increases causing the raindrop to flatten and even develop a depression. Finally, when the radius exceeds about 4 mm or so, the depression grows almost explosively to form a bag with an annular ring of water and then it breaks up into smaller drops."
good question,Raindrops are Round...At First. Raindrops start out as round high in the atmosphere as water collects on dust and smoke particles in clouds. But as raindrops fall, they lose their rounded shape. Instead, a raindrop is more like the top half of a hamburger bun. Flattened on the bottom and with a curved dome top, raindrops are anything but the classic tear shape. The reason is due to their speed falling through the atmosphere.