Rice Field Bubbles: Gotcha! Why?

[Hornbein]

Bubbles of air were rising in some water in a rice field. The bubbles would float around at random for a while. If two bubbles got within a certain distance of one another they would very quickly merge. It looked like a predatory larger bubble pouncing on the smaller prey. Gotcha! Why is that? (I know the answer.) There was no soap or other surfactant in the water.

 

[hmmm27]

gravity.

 

[phinds]

Bubbles of air were rising in some water in a rice field. The bubbles would float around at random for a while. If two bubbles got within a certain distance of one another they would very quickly merge. Why is that? (I know the answer.) There was no soap or other surfactant in the water.

If you know the answer, why are you asking the question?

 

[Hornbein]

If you know the answer, why are you asking the question?

I think it is interesting and readers would have fun contemplating it. The puzzle is not obvious but easy enough that some will get it without much trouble. I learned from it and am sharing so that others may learn too.

 

[Baluncore]

Surface tension will cause nearby bubbles to be attracted as the water level is slightly higher, attracted to the bubble wall, but slightly depressed under the bubble since the gas pressure in the bubble is greater than outside.
Are the bubbles composed of O₂, CO₂, or H₂S ?

 

[Hornbein]

Surface tension will cause nearby bubbles to be attracted as the water level is slightly higher, attracted to the bubble wall, but slightly depressed under the bubble since the gas pressure in the bubble is greater than outside.
Are the bubbles composed of O₂, CO₂, or H₂S ?

Plain ordinary air entrained by moving water.

 

[Baluncore]

The presence of a surfactant is denied, yet the bubbles could not remain on the surface if there was not a natural surfactant, such as a protein in the water.

Maybe a small animal is hanging from the small bubble, with a predator hunting those animals, and accumulating the gas.

"Contribution of Ebullition to Methane and Carbon Dioxide Emission from Water between Plant Rows in a Tropical Rice Paddy Field".
https://www.hindawi.com/journals/isrn/2015/623901/

 

[DaveC426913]

Don't bubbles do this naturally?
Is perhaps the question: why are there bubbles?

Does it have to do with starch from the rice?

 

[Baluncore]

Has this anything to do with the 4^th, 5^th and 6^th derivatives ?

 

[Frabjous]

It’s been a week, what’s the answer?

 

[Baluncore]

In what field of science does the answer lie.
I think we need a hint or a clue.

 

[Hornbein]

The weight of each bubble presses down the surface of the water. If two bubbles get close enough together then the bubbles suddenly slide "downhill" towards each other and merge.

As to "why are there bubbles," they didn't last long, only a few seconds.

 

[Baluncore]

As to "why are there bubbles," they didn't last long, only a few seconds.

How long did the big bubble last ?

 

[Bystander]

Do we need a "So what?" emoji?

 

[hmmm27]

Not before we get a facepalm emoji.