WATERFALL appears WHITE in colour - WHY??

        You should have enjoyed the beauty of a WATERFALL. The MILKY WHITE WATER pouring down from great heights with  fizzing sounds really looks very beautiful and makes a great impact on our inner feelings.It changes our mood and makes us feel happy for getting a chance to see such a beautiful scene.

        But have you ever wondered why the WATER white in  colour while falling from great heights?? And whats that SOUND you hear?? Read on and you will get the answer.. 

         We all know Water is COLOURLESS.Even when water is flowing in canals, rivers etc. water appears as  usual, sometimes brown if its so muddy.But once it starts falling form a higher place it looks milky white.So something is happening to the water when it starts falling from above.

         Yes, it happens when water starts falling. In short, the water gets aerated. Before explaining this I have to tell you something about DISSOLVED OXYGEN.As the name says there is some amount of oxygen which is dissolved in the water. This dissolved oxygen is nothing but the small BUBBLES what you see rising above when you boil water.

        When the water falls from a height, its flow changes from Laminar to Turbulent.Laminar flow is a kind of  uniform and smooth flow.Turbulent flow is a RAPID and non-uniform flow where all the layers of the water gets mixed. I will give a small example for you to know the difference between laminar and turbulent flow. After you blow off a candle, the smoke (vapour of wax) rises up. Please see the image below. The smoke leaving the WICK of the candle flows uniformly and smoothly. This is called LAMINAR flow and the flow of smoke little above is non uniform and not smooth. This kind of flow is called TURBULENT flow.

           When the flow changes from Laminar to Turbulent, a sudden change occurs in the parameters  of the flow. This causes the DISSOLVED OXYGEN to evaporate releasing oxygen in the gaseous form and millions of small WATER BUBBLES are formed which gives the WHITE colour to the water. Air also gets sucked in because of the flow of the water. The hissing sound what you hear is the sound of the air getting mixed with water at the top and again the air gets relieved at the bottom. 

          I have to tell you one more thing that clearly understanding all the characteristics of turbulent flow is not easy.. Nobel Laureate Richard Feynman described turbulence as "The most important unsolved problem of classical physics."
         I hope now you have understood why a WATERFALL appears WHITE in colour. Dear reader, please comment about this post.You can share this FACT with your friends by clicking the SHARE icon below. Thank you.