The real shape of a falling raindrop

Contrary to what you might think, raindrops are not actually tear-shaped. In fact, some raindrops are almost spherical when they fall while others look like the top of a burger bun because of the flow of air.

High up in the atmosphere, water droplets form around dust particles in a spherical shape because of the surface tension of water. Smaller raindrops then have a higher surface water tension while larger raindrops have a lower surface water tension.

When the raindrop is big enough to fall, it does. If the raindrop is less than one millimeter in size, it is able to maintain is spherical shape due to its surface water tension. However, if it is between 2-3 millimeters, the raindrop will being to lose its shape as it falls.

This is because air flow on the bottom of the raindrop is greater than the airflow above it creating pressure. This then causes the bottom of the raindrop to flatten out, while the top of the rainfall remains curved, like a burger bun.

But don’t raindrops often collide with other raindrops when they are falling making them bigger? The answer is yes. However, once the raindrop gets to around four millimeters, they fall apart in the atmosphere and continue to fall as smaller raindrops.

So next time you want to doodle some raindrops, you’re better off drawing them as almost spherical or like the top of a burger bun!