July 15

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Three reasons why ice cubes have white clouds within them

By Juman Hijab

July 15, 2021

clouds, ice, white color

ice cubes with central white cloud

Ice cubes with trapped air bubbles

Clear ice cubes

Clear ice cubes: no air bubbles

Ice cubes are not always clear

I spent a lot of trial and error to create crystal-clear ice cubes. You can see the results above. On the left are the standard ice cubes our freezer produces. On the right are ice cubes produced using the technique suggested here. Don't the ice cubes on the left look as if they have miniature clouds or fog trapped in them?

Are those white patches the same as clouds? Yes, in many ways, the whiteness and haziness that you see on the left forms in the same way that clouds form, with 3 major differences.

Why do ice cubes have white clouds in them?


Here are the three reasons:

  • First: Liquid water contains air bubbles.
  • Second: When the water freezes, the air bubbles are frozen  in place.
  • Third: This produces a mass of disorganized bubbles. Due to the disorganization, light  is refracted chaotically without passing through. The white light is reflected back to the viewer. Element

How does this apply to other objects that are white in our environment?

White air bubbles beer

Head of beer pint

Spitting crab

Crab foaming "at the mouth"

Whipped egg whites

Beaten egg whites

What other objects have trapped air bubbles?

Here are three of  15 objects that look white

  • Beer head: have you noticed that the beer is an amber color, but the beer head is pure white? 
  • Frothing saliva: "foaming at the mouth": the picture shows a crab sputtering air bubbles. The foam looks quite white to me.
  • Beaten Egg whites: egg whites are translucent. When the eggs are beaten, air bubbles are entrapped are held in place by the proteins in the egg white. The result is a white color.

The reason I chose those three examples is to highlight that it is not only frozen water that holds trapped air bubbles in place. For example, in a beer head, it is the malt proteins that hold the gas bubbles. Similarly, in frothing saliva, it is liquid water with proteins + ions mixed in. Sea foam is an highly exaggerated form of "frothing". This foam forms when there is a lot of protein in the waves from decaying algae. Finally, in beaten egg whites, it is the protein material from the egg that holds the air.

Ginger ale bubbles

Ginger ale bubbles

Nitro cold brew

Nitro cold brew

White Methane clouds on Neptune.

White Methane clouds on Neptune.

Does it have to be air?

What other gasses create whiteness?

  • Carbon dioxide:  Many drinks (and water) are carbonated to produce a tingly taste and fizzy texture. 
  • Nitrogen: Nitrogen gas is often infused  to coffee (as well as beer and other drinks) to give a creamier, thicker texture as well as a less acidic flavor to the drink and a longer lasting head.
  • Methane: Methane gas is prominent in the gas giants (see for example, Neptune), as well in several of the moons (like Titan). The gas freezes in the upper atmosphere and forms white, cirrus clouds. Of note, methane tends to absorb red light; the reason the clouds appear white may be due to other elements (such as phosphorus or ammonia crystals).

In summary, it does not matter what the gas is. As long as the gas reflects light, a disorganized group of trapped gas bubbles will appear white.

Picture credits: 

  1. Hijab, J. Ice cubes with entrapped air bubbles. Winter, 2018.
  2. Hijab, J. Frozen ice cubes, using system to remove air bubbles, Winter, 2018.
  3. Martin Garrido. Beer, Dec 27, 2011.
  4. devra . Spittling crab in Morro State Park Marina, July 5, 2010.  
  5. Scott Mindeaux. whipped_egg_whites, July 6, 2005. 
  6. F Delventhal. Ginger Ale, April 30, 2010.
  7. Fiona Henderson. Nitro Cold Brew, Feb 20, 2016.
  8. NASA Hubble Space Telescope. Hubble Sees New Dark Spot on Neptune, July 1, 2016.

Juman Hijab

About the author

Juman is a retired physician after having been in clinical practice for more than four decades. Her lifelong interest has been in the chemistry of life.

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