Nature / Earth / Everyday water physics
Why falling raindrops are not shaped like teardrops
Small drops are nearly round. Larger ones flatten and can break apart. The difference between open air and a window explains the familiar confusion.
Draw rain and you will probably sketch a round bottom with a pointed tail. It is a wonderfully readable symbol. It is also a poor model of a drop falling through open air. Real raindrops change shape as the balance between surface tension and airflow changes.
Why small drops are nearly round
NASA’s Anatomy of a Raindrop explains that surface tension holds small water drops in a roughly spherical shape. This is often compared with a skin, but there is no separate membrane around the water. The comparison describes the behaviour of its surface.
As drops grow, the moving air around them becomes more important to their shape. NASA describes larger falling drops as having a flatter underside and a rounded upper surface. Keep that orientation in mind: the familiar pointed tail is not the defining feature of an ordinary falling raindrop.
Bigger does not simply mean a bigger sphere
The US Geological Survey’s explanation describes the competition between surface tension and the pressure of the surrounding air. Small drops remain comparatively round; larger ones become more distorted. A sufficiently large drop can break into smaller drops instead of maintaining one ever-growing shape.
These are useful tendencies, not a set of rigid moulds. When someone says a large drop resembles a bun or a flattened sweet, treat that as a guide to its outline. The comparison does not mean every drop has an identical profile throughout its fall.
The window is a different situation
Why, then, do the drops on a window look stretched? USGS points out that water clinging to glass is being distorted by contact with the surface. Likewise, a drop still hanging from a tap is not in the same situation as a drop travelling through the air. The surroundings are part of the explanation.
| What you are looking at | What to check first |
|---|---|
| A bead on a window | How contact with the glass affects the shape |
| A drip beneath a tap | Whether the drop is still attached |
| Rain falling in open air | How drop size and airflow affect its outline |
The cover shows the first situation. It offers a familiar place to notice water, but it should not be used as a diagram of airborne raindrops.
Why the outline matters beyond a drawing
Drop shape also affects measurement. NASA’s precipitation FAQ explains that flattening changes the radar echo when a drop is viewed from the side; for the space-based GPM precipitation radar, the effect is much smaller. The direction of observation matters as well as the object being observed.
That makes a useful habit for everyday science: before asking whether a picture looks right, ask what situation it represents. The distinction is equally helpful when separating an ordinary wave from the longer cycle described in our guide to spring and neap tides.
References
- NASA Global Precipitation Measurement Mission. (n.d.). Are raindrops really shaped like teardrops? https://gpm.nasa.gov/resources/faq/are-raindrops-really-shaped-teardrops
- NASA Global Precipitation Measurement Mission. (2013, December 4). The anatomy of a raindrop. https://gpm.nasa.gov/science/anatomy-of-a-raindrop
- U.S. Geological Survey. (2018, June 6). Are raindrops shaped like teardrops? Water Science School. https://www.usgs.gov/water-science-school/science/are-raindrops-shaped-teardrops
Reading notes and scope
Checked 27 September 2026. The linked NASA and USGS explanations support the qualitative account. Exact size thresholds are omitted because these introductory sources use different size descriptions; this article is not a drop-sizing guide or a report of a new experiment.