A giant raindrop ever recorded is between 8.8 mm and 1 cm, i.e., only half a wide in diameter as a US penny. This giant raindrop was measured by scientists in the clouds above Brazil in 1995 and in the Marshall Islands in 1999.
Before we get started, let’ talk about how raindrops form? Rainwater droplets are more than just water. The water vapors in the cloud have something to do with condensation, without which there would be no rain. Little dust particles, smoke, or even salt, sit at the center of the rainwater droplets that begin to form a cloud. These tiny droplets are usually between the diameter of 0.001 and 0.005. All because of relatively stable cohesive forces between the water molecules, these small droplets, at first, form a spherical shape. As these tiny water droplets buffet around in the air, they collide with other droplets and transform into larger and larger droplets.
The whole story behind the raindrop
The water drop will ultimately fall to the Earth, and surface tension of the water keeps the drop spherical. The water drop may overcome by the pressure of airflow on its lower surface. As the raindrop continues to fall on the Earth, it continuously grows or shrinks. Because of this whole phenomenon, the average rainwater droplet that collides with your head is only around 1 or 2 mm across. As discussed before, as per the scientists, the reason behind the size of a record-holding raindrop found in the clouds over Brazil is relatively large particles of ash from fires in Brazil’s rainforest.
To conclude, it is technically not possible to have a raindrop that contains gallons of water. But cases like the raindrops mentioned above can appear in the future.
