White objects: Really white water
When is water white?
In this article, I list 15 really white objects, including water. As you go down the list, imagine what is happening at the microscopic level.
I also discuss this further in the course when is water white. In the course, I discuss different states of water that are white. Whitewater, ice cubes, snow, and clouds are all white for the same reason.
15 natural objects that are really white
What do white objects have in common?
They have a reflection of white light off a disorganized mass of gas or air molecules. These molecules are held together in an transparent netting with different sizes of packets of gas. The packets create a chaotic jumble of interfaces for light to reflect off in all directions. The result is white light reflected back to us, creating white objects.
Polar bear - white fur
1. Polar bear fur
Polar bear fur is made of clear hollow tubes. Those countless tubes cover a skin that is black. Yet, polar bear fur looks white.
Ice cubes with trapped white air bubbles
2. Ice cubes
Ice cubes that are made in ice cube trays often have a disorganized white center. It is possible, though, to create perfectly clear ice cubes at home.
Hail overlying blue car
3. Hail
The image shows hail that has fallen on a blue car surface.
Hail is frozen ice compacted together. However, there are interfaces between the frozen water crystals (which are colorless) and the suspended air pockets (which don't absorb light). The light cannot go through the hailstone and is reflected back to us as white light.
Cumulonimbus
4. Cumulonimbus clouds
Cumulonimbus clouds are those towering, thunderous, and ominous looking monsters. Capped with a mushroom or an anvil-shaped top that is pure white.
Ship's wake
5. Wakes of boats and ships
It is a given that boats, ships, jet-skis have a white tail. This is the foamy aerated water that is churned up as the boat makes it way forward.
White objects: How white is white?
The whiter the color of the object means that there is a higher percentage of white light that is reflected back. The higher the percentage, the starker the whiteness.
Objects that have spaces for light to hide in (like clouds) will have a softer white quality. Objects where the reflective surfaces are tightly connected and/or are highly reflective will have the whitest of white quality.
Beaten egg whites
6. Whipped egg whites
Egg white proteins are translucent; however, when whipped they become pure white.
Lake and sea foam forms by wave agitation of water rich in dissolved organic matter.
7. Sea and Lake foam
The same concepts that creates foamy liquids creates sea and lake foam. Except the foaming bubbles that are part of sea/lake foam last much longer than those in a glass of soda. Seam foam contains proteins from algae and other organic matter.
Head of beer pint
8. Beer head
The gas that produces the "head" in a pint of beer is carbon dioxide, though nitrogen is sometimes added to produce a longer lasting, less acidic taste.
White clouds
9. Tops of clouds
The tops of clouds are the whitest. Next time, Take a look at how pure white they can be. This is because the updrafts of air expand as they go into higher altitudes and lower pressure conditions. Also any water/ice particles tend to sublimate because of the lower pressures.
This encourages the outside surfaces of the tops of clouds to be completely air-filled, reflecting white color (of note, the water/ice particles stay congregated in the centers of cumulus clouds).
White snow on deck
10. White snow
Blinding white snow. As white as snow. A blanket of fresh white snow. Those images are clear in our mind's eye. And the reason snow is white is the same as why clouds are white or polar bear fur is white.
White objects: Is an ermine always white?
Other creatures have pure white coats, like Arctic hare and Arctic fox, as well as the Ermine.
Light is a strong trigger for cell change. For example, white flowers develop pigment molecules in their cells under the influence of light. When the same plants are kept in the dark, the flowers remain white.
In animals, melanin is the primary pigment molecule that gives hair and skin their variations in dark and light colors. However, some animals change the color of their fur seasonally: from brown in the summer to white in the winter.
Soapy foam
11. Soap bubbles
Even soap colored green will form white bubbles of soapy foam. One could have black soap and still the foam will be a pure white.
Keep in mind that it has to be a mass of disorganized bubbles that contain air. A few large soap bubbles will allow the light to pass through such that we can see what is beyond the bubble.
Splash
12. Crests of waves
Liquid water is white at the interfaces of water and air when there is turbulence.
Whitewater
13. Whitewater
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.
Crab foaming "at the mouth"
14. Spluttering crabs
It's not only dogs and cats that foam at the mouth. Even crabs - forcing air out of their gills - will produce foam when out of the water.
Ginger ale bubbles
15. Ginger Ale
It is not only air that creates a gas/liquid interface. Shaking a can of soda will create a mass of white CO2 bubbles.
White objects: Why does an ermine turn from brown to white?
It turns out that the principle trigger for this is the shortened daytimes, with less exposure to daylight. There are multiple benefits for a change from a brown coat to a white one when the season changes.
Interestingly, it is not only camouflage that helps white-coated creatures survive in the snow. It turns out that white fur is more insulating than brown fur: White fur has more air in the hair shafts; air is a poor heat/cold conductor. Thus, animals can thrive in cold Arctic temperatures.
Picture credits:
- Header image:USFWS Mountain-Prairie. Ermine, the long-tailed weasel in its white winter coat, March 11, 2016.
- Jessica Merz. Polar bear. Flickr photo-sharing. Taken on Feb 20, 2006.
- Hijab, J. Ice cubes with entrapped air bubbles, 2019.
- pfly. Snowy blue car. It kinda hail-snowed, April 18, 2008.
- Bernard DUPONT. Cumulonimbus Cloud, Somewhere above, Nov 14, 2015.
- Alex O'Neal. Ship's wake, July 25, 2008.
- Scott Mindeaux. whipped_egg_whites, July 6, 2005.
- James St. John. Lake foam along the shoreline of Storr's Lake (San Salvador Island, Bahamas), March 24, 2007.
- Martin Garrido. Beer. Flickr - photosharing. Taken on Dec 27, 2011.
- Vladimer Shioshvili. Clouds in Dusheti, Georgia, May 21, 2006.
- Hijab, J. Snow on deck, winter, 2018.
- By jocic. Soapy foam on man's hand, ID: 160713749.
- Lukasz. Splash, Feb 23, 2006
- U.S. Department of the Interior. Whitewater, A skilled whitewater kayaker navigates Raymondskill Creek, Delaware Water Gap National Recreation Area, Pa, June 17, 2013.
- devra . Spittling crab in Morro State Park Marina. This crab was foaming at the mouth. Flickr photo-sharing. Taken July 5, 2010.
- F Delventhal. Ginger Ale. Flickr photo-sharing. Taken on April 30, 2010.