More reasons why objects are white

Article 4 Module 2

white flower

White flowers

Some flowers create a pigment that echoes all light, creating white flowers.  But most of the times, the white color in flowers denotes the absence of any pigment. In such cases, the white "color" is due to the same reasons that clouds and snow are white: the presence of disorganized air molecules that reflect white light back to us. For example.  

  • A waxy covering on the surface can produce a white color: The wax traps air which reflects white light
  • Petals often harbor air spaces between the cells, creating white flowers
  • A covering of surface hairs can trap air between them; such petals or leaves can look white. 
  • The vacuoles within the cells can have air pockets allowing the petal to reflect white light

White butterfly wings

How about white butterfly wings?

Keep in mind, that not all white things in nature are due to reflection off a bunch of gas bubbles. The microscopic structure and arrangement of the fibers can reflect light back to us, creating a structural white color.

Examples include  wings of butterflies or bright-white beetles or the white bark of birch trees.

In some of those cases, the actual material is colorless and transparent. However, because it scatters white light, it will appear white. 

Salt and sugar

What about Salt and Sugar? 

Two very common objects that look as white as snow. 

Both have crystals that are clear and transparent. However, when crushed into powder or a granular consistency, multiple interfaces are created. White light is bounced around the surfaces and reflects back to us. The result is a white color.

Two primary reasons for white color in nature

You can't go wrong if you remember the two primary reasons for the white color of natural objects:

  • reflection of gas/air molecules that are held in place in a disorganized state close to the surface of the object
  • reflection of white light off a structural arrangement of fibers (or interfaces) close to the surface

Picture credits:

  1. Jevgenijs Slihto. Birch. Flickr - photosharing. Taken on March 7, 2015
  2. Christoph Zurnieden, white-flower-002. Flickr photo-sharing, taken on Sept 18, 2012. 
  3. Aleksey Gnilenkov. Cabbage White butterfly (Pieris canidia). Flickr photo-sharing, taken on March 29, 2012.
  4. By 5 second Studio. Shutterstock, ID: 732033907. Inscription Sugar and Salt on grey wooden table.