What holds air bubbles in place?
Article 2 Module 1
In the first lesson, I identified the primary reason for the whiteness in natural objects.
When air bubbles of different sizes are trapped in a transparent material, the light is refracted in multiple directions. It is as if the light entered a hall with innumerable nano-sized mirrors at different angles to each other. Does that clarify why snow is blinding?
The air molecules are held hostage in different sized packets by a transparent netting. If the netting was not transparent, we would not get the effect of a pure white color coming back to us.
What kind of mesh or web holds air bubbles captive? There are three kinds.
1. Liquid, cold, or frozen water molecules
When water vapor molecules cool down, they form hydrogen bonds that are very sticky. Those hydrogen bonds bind water molecules together forming a strong net that holds air molecules captive.
The white color is due to a reflection of white light off disorganized molecules of air held together in a web of liquid or frozen water.
For clouds and fog, water vapor molecules cool down at higher altitudes in the troposphere. This allows the formation of a web of connected vapor molecules.
The web holds microscopic liquid water droplets intermingled with bubbles of air.
There are proteins released in the liquid of the crab's saliva; similarly there are proteins in egg whites and in beer foam. Mynah bird feathers and polar bear fur are made of keratin which is also a protein.
All the instances show proteins helping forming a transparent mesh or tube that entraps air molecules in one position.
Adding cohesive molecules to foamy liquids makes the foaming bubbles last longer. This is the reason sea foam is formed. Proteins from broken down biodegradable material, like algae, mixes with the water. Thin layers of protein and water hold countless bubbles in place.
3. Fats or soaps
Pockets of air are not only encompassed with water or proteins. Other natural materials hold air bubbles hostage. For example, molecules such as fats (whipped cream) and soaps are really good at this. Even glass can trap air bubbles.
Fat globules of whipped cream: one needs at least 30% fat in cream to allow air bubbles to be held in place for a whipped texture.
In the instances above, fat or soap molecules form a transparent mesh that entraps air molecules.
Detergents/soap foams: A white foam develops when we use soap to lather our hands. Contrast the picture of the white foam with its multitude chaotic mass of bubbles with the see-through single soap bubble shown here.
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- By jocic. Soapy foam on man's hand. Shutterstock. ID: 160713749.
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- By LVV. Transparent glass ball with air bubbles inside on a blue background. Shutterstock. ID: 45809566.