July 21, 2009, 9:41 am
Why raindrops come in many sizes
No two raindrops seem to be the same size - and now we can see why!
What was discovered?
As individual rain droplets (about 6 mm diameter) fall through the air, the air resistance can overcome the surface tension of the water molecules (which holds them together as a single droplet) so that the droplet splits into many smaller droplets of different sizes.
Remarkable video photography can capture the events and replay in slow motion so that scientists can see every stage in the splitting of the rain droplet.
Why is it important?
Previous explanations for the different sizes of raindrops included the idea that they crashed into one-another as they fell, sometimes joining together, sometimes splitting into smaller droplets - but the problem was that as they fall, very few raindrops actually crash into others...
now we can see that falling raindrops do not need to crash into others to split up, they can do this alone as they fall through air!
See what happens when a rain droplet hits a puddle of water in this amazing MoleClues video