Why a drop of rain water is round?
A rain drop is round because when a drop of water is falling or suspended in the air it’s own surface tension pulls the surface of the raindrop inwards equally all the way around so making it spherical in appearance (Rose below explains this science more effectively). This is only distorted by air movement around in. Water will naturally shape it’s self in a globules if it is not resting on anything. You probably seen astronauts play with water in orbit in there space vehicles to see this.
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. A raindrop falling through the atmosphere forms as a roughly spherical structure due to the surface tension of water. This surface tension is the “skin” of a body of water that makes the molecules stick together. The cause is the weak hydrogen bonds that occur between water molecules. On smaller raindrops, the surface tension is stronger than in larger drops. The reason is the flow of air around the drop.
