Precipitation education: The shape of raindrops

KOIN 6 Weather Kids

Editor’s note: The KOIN 6 Weather team is presenting weather and science lessons to help serve our teachers and students as schools close across the nation amid the novel coronavirus response. Click here for more lessons, and click here for complete coverage.

PORTLAND, Ore. (KOIN) – In your mind try to imagine a raindrop. What does it look like? Is it a circle? Is it a teardrop shape? Is it rod shaped? Does it look like a hamburger bun? There are a few correct answers to that.

Weekend Meteorologist Joseph Dames

More often than not, raindrops are depicted as a teardrop shape. In fact, most cartoons and images you see, use teardrops. It is the universal symbol for rain; however, it isn’t accurate! If by chance you were thinking rod shaped, that is also incorrect.

Now, I’ll admit, if I was going to draw rain, I would also use a teardrop. It looks nice and it gets the point across. But you may want to start thinking about drawing a few different shapes when you think about adding rain to your creations.


There are a few options that you can choose from, technically, depending on the size. If they’re smaller than 2mm (~.08 inches) they will be spherical, and if they happen to be larger than that, raindrops take on the appearance of a hamburger bun! They are more round on the top with a flat bottom.

How do raindrops take on these forms? As drops fall, some may combine with others and other may not. The larger drops tend to fall in a hamburger bun shape because the air pressure against the drop as it is falling is at its greatest at the bottom of the drop. That greater pressure will cause the drop to flatten at the bottom. Sides are rounded off because the pressure is lighter and it allows for them to expand. Additionally, the airflow isn’t as disruptive on the top, where small air circulation occurs, creating that soft top.

Portland, Oregon, receives around 36 inches of rain a year. That is a lot of water! Some years we even push more than that. Imagine all those hamburger bun raindrops that Portland may see a year.

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