Get smart curated videos delivered to your inbox every week.      
The Kid Should See This

Coalescence cascade: The bouncing droplet in slow motion

What is a coalescence cascade?

When droplets of water contact the surface of water, it doesn’t actually get absorbed straight away like you may think it does. What happens is it gradually bounces up and down until it is absorbed.

Underneath the droplet is a very thin layer of air, which allows it to sit temporarily above the surface. The air layer takes a bit of time to be pushed aside by the droplets weight. As the air moves from under the droplet, the surface of water pinches at water for a split second absorbing it. However it happens so fast that the connection is cut off between them and so a smaller droplet which hasn’t been absorbed bounces up.

As contact is made, waves are generated at the point of contact which surround the droplet, and go up the sides. This produces a force which allows the water droplet to leap up into the air. As it leaps up into the air, air fills the space underneath and the droplet once again sits on the thin layer of air. This process repeats until the mass of the droplet is so small it can just be absorbed by the water.

Watch more drops of liquid.

Thanks, Jethro and @Junephine.

This Webby award-winning video collection exists to help teachers, librarians, and families spark kid wonder and curiosity. TKSST features smarter, more meaningful content than what's usually served up by YouTube's algorithms, and amplifies the creators who make that content.

Curated, kid-friendly, independently-published. Support this mission by becoming a sustaining member today.

🌈 Watch these videos next...

Pacific Light: Water, ink, oil, and soap form a tiny universe of color

Rion Nakaya

Jell-O Tennis – The Slow Mo Guys

Rion Nakaya

Coalescence cascade: A water drop dances in slow motion

Rion Nakaya

Go inside an ice cave to see nature’s most beautiful blue

Rion Nakaya

What is surface tension? Ask a water strider.

Rion Nakaya

Mercury Hz: Sound waves passing around & through mercury

Rion Nakaya

See the unseen: Cymbal at 1,000 frames per second

Rion Nakaya

Float by Susi Sie

Rion Nakaya

Water balloons falling (and bouncing) in slow motion

Rion Nakaya