Water
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Waves and bubbles

Article 1 Module 1

Liquid water splash - White water

Splash made by a swimmer

Turbulent water and air



 Liquid water is white at the interfaces of water and air when there is turbulence.



Wave crests, breaking waves, waterfalls, the wake of ships and boats, river whitewater, water splashes, and water jets are all examples of turbulent water/air interfaces. 



What happens at turbulent water/air interfaces?



Agitated water at the air interface encourages aeration of liquid water with air bubbles.




Ginger ale bubbles

Ginger ale bubbles

What about bubbles from soda?


It does not have to be air molecules. Any gas that does not absorb light has the capacity to create bubbles that are white. 


Shaking a can of soda will create a mass of white CO2 bubbles. 




Here's what happens with agitation of water and air:

 


  • Water dissolves some of the air 


  • The churning water creates air bubbles and air pockets 


  • The turbulent water generates water droplets that are  held in place within air pockets.



In other words, churning water  creates environments where air bubbles and water mix together.



The gasses within air (Nitrogen, oxygen, carbon dioxide) do not absorb light.



Light gets refracted (bounced around) in the different interfaces between liquid and gas.



It is the disorganization of those interfaces - a mass of bubbles - that prevents light from making its way through. 



Since none of the light is absorbed and some of it is reflected back to us; we see the mass of bubbles as white. 

Conclusion


A disorganized mass of air bubbles held in place by water will reflect light. 


This is the whiteness you see in wave crests and splashes.


Picture credits:


  1. Hijab J. Breaking waves, Cape Cod. December, 2019.
  2. Horia Varlan. Splash made by a swimmer jumping into the sea. Flicker - photo sharing. Taken on Aug 5, 2009.
  3. F Delventhal. Ginger Ale. Flickr photo-sharing. Taken on April 30, 2010. 
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