Raindrop Shape: A Falling Drop Is a Bun, Not a Teardrop

TL;DR: Raindrop shape is nothing like the tear you were taught to draw. A falling drop is a flattened bun, round on top and pushed flat underneath by the air rushing past it. Small drops stay almost perfectly round. Past about four millimetres the air wins, the drop stretches into a parachute and bursts, so a giant raindrop never reaches the ground.

Key takeaways

• The real raindrop shape is a flattened bun, round on top and flat underneath, never a tear.
• Drops smaller than about 1 mm across stay almost perfectly spherical, held that way by surface tension.
• The Met Office describes the raindrop shape of a larger drop as a hamburger bap, flattened underneath by air resistance.
• NASA puts the parachute stage at drops larger than 4.5 mm, just before they break up into smaller ones.
• The teardrop picture comes from water pinching off a tap or streaking down glass, not from rain in free fall.

Last updated: 21 August 2026

What is the real raindrop shape?

The real raindrop shape is a flattened bun. A drop falling through air is round over the top and flat, sometimes slightly dented, underneath. NASA’s Global Precipitation Measurement mission describes it as the top of a hamburger bun. The pointed tear you were taught to draw does not exist in free fall.

Size decides raindrop shape more than anything else. Drops under about a millimetre across are almost perfect spheres, because surface tension pulls the water into the shape with the smallest surface area for its volume. That is drizzle, and drizzle really is round. Grow the drop, and it starts to fall fast enough for the air to have an opinion.

Forget everything you were taught in primary school. Raindrops are not tear-shaped. Met Office

Why does a falling raindrop have a flat bottom?

Because the air does not flow evenly around it. A falling drop meets far more airflow underneath than over the top, and that pressure presses the base flat while surface tension keeps the dome. The raindrop shape you end up with is the settlement between those two forces.

Because the airflow on the bottom of the raindrop is greater than the airflow on the top of the raindrop, this creates pressure on the raindrop’s bottom, and its shape becomes flattened. NASA Global Precipitation Measurement mission

Speed is why the effect grows with size. A large raindrop settles at a terminal fall speed of about ten metres per second, roughly 20 mph, according to the Weather Guys at the University of Wisconsin, while smaller raindrops come down at nearer 2 mph. The faster it falls, the harder the air pushes back, and the flatter the underside gets.

How big can a raindrop get before it breaks up?

Not very. Once a drop passes roughly four millimetres the airflow hollows out its underside, stretches it into a thin parachute and tears it apart. NASA puts the parachute stage at drops larger than 4.5 mm. Break-up is why rain arrives as a spray of modest drops rather than water balloons.

In the laboratory, break-up usually happens at about five millimetres. A research aircraft flown by the University of Washington cloud and aerosol group recorded drops of at least eight millimetres, and perhaps a full centimetre, over Brazil in 1995 and over the Marshall Islands in 1999, all of them measured inside the cloud. Nothing that size makes it to the ground intact.

Why do we think raindrops are teardrop shaped?

Because we have only ever watched still water do it. A drop hanging off a tap or a leaf stretches into a tail as it pulls away, and a drop running down a window is dragged into a tail by friction. Neither has anything to do with raindrop shape in free fall.

The physics department at West Texas A&M University traces the misconception to exactly that. Water streaking down glass is tear shaped for the same reason a tear on a face is, which is friction, and air offers nothing like it.

The Physics Van at the University of Illinois makes the same point about taps. As the drop falls away, less and less of it is still hanging on to the water above, and that is what pinches the tail. The moment it lets go, surface tension pulls it straight back into a ball.

Why does raindrop shape matter for weather radar?

Because the shape carries information. Dual-polarisation radar sends pulses both horizontally and vertically, so it can tell a small sphere from a large flattened drop. Reading raindrop shape off the returned signal tells forecasters whether they are looking at drizzle or at rain heavy enough to flood.

The Met Office explains how the upgraded UK radar network reads drop shape, and notes that the heavier the rain, the larger and more squashed the drops become. A geometry lesson turns into a flood warning.

Does this change how you read rain on a site?

A little, yes. Rain is not one uniform thing arriving at one steady rate, and the raindrop shape story is a reminder that what looks even through a window is nothing of the kind. On the ground, the only honest way to know what a storm did to a site is to measure it while it happens.

That is the work we spend our days on. We use non-contact instruments like the AQUAIOT Radar for smart water level monitoring on tanks, chambers and flood-risk assets, the Smart Water Butt for rainwater harvesting and stormwater, and continuous sewer and drainage monitoring for what happens underground. If you enjoy this sort of thing, our round-up of UK water facts has more.

Frequently asked questions

A quick recap of the questions people ask most about raindrop shape.

Does raindrop shape change as the drop falls?

Yes. A drop starts out almost spherical up in the cloud, and as it grows and speeds up the air flattens its underside into a bun. Grow it further and the base hollows into a parachute before it bursts. Raindrop shape is not fixed, it tracks the size and the fall speed of the drop.

Are raindrops ever teardrop shaped?

Only while they are still attached to something. Water pulling away from a tap, a leaf or a gutter stretches a brief tail as it separates, and water running down glass is dragged into a tail by friction. In free fall through air there is nothing to hold that tail, so it collapses almost at once.

How big can a raindrop be?

Rain generally arrives between about half a millimetre and a few millimetres across, and laboratory work puts break-up at roughly five millimetres. Research aircraft have recorded exceptional drops of at least eight millimetres inside tropical clouds, but a drop that size cannot survive the fall. Anything smaller than half a millimetre counts as drizzle.

How fast does a raindrop fall?

A large raindrop reaches about ten metres per second, roughly 20 mph. Smaller raindrops come down at nearer 2 mph, and cloud droplets drift at around a centimetre per second. That gap in speed is exactly why big drops end up flattened underneath while small ones stay almost perfectly round.

By Gianbattista Porru, Digital and IoT lead at AQUAIOT.