Many of the most beautiful scenes in nature spring from the interaction of water and light. These abundant ingredients are also counted as two of the most essential features for life as we know it on Earth. The physical properties of water as a molecular substance and light as an electromagnetic wave are completely different, but their interactions exhibit a complementarity that provides us with scenes of unending beauty.

Waterfalls fascinate us with their accelerating rush of falling water, but a waterfall glistening in the sunlight, reflecting off the ever-replenished flow and piercing the mist boiling out of the crashing cauldron below, is breathtaking. Even more arresting to our sight is when, in winter, flowing water transforms into frozen motion. I remember well, one particularly cold winter, seeing Snoqualmie Falls in Washington State completely frozen throughout its 268-foot drop. We wonder how such violently moving water could ever freeze, seemingly in stop-motion. 

A Measure of Peace

Near where I live a walking and biking trail runs along a gently flowing river. The very existence of continuously flowing rivers of liquid water on the surface of our planet is a condition for life on Earth. But today I would take us further than appreciating water for its survival benefit and commend to our attention its aesthetic qualities. Water in rivers, streams, brooks, lakes, and oceans refreshes our minds and emotions and has served as inspiration for countless artistic expressions. A walk along an ocean strand, watching the rhythmical action of the waves and viewing the merging of sky and water, never fails to help us towards a measure of peace.

The play of light on water can vary as greatly as our moods. The waves seem steel-grey when the sky above is cloud-covered and stormy. Casting ovations of spray upward, the breaking waves in sun and wind beckon us to abandon our frustrations and join in their wild chorus. The light of the setting sun on a quieted ocean breast, reflecting the last rays of light at the end of the day, brings us once more beyond ourselves with the gift of resplendent hues spanning the orange-red end of the visible spectrum.

Literature reflects our intimate awareness of the beauty of water and light.

A swift rain, like a rain of the early summer, began to fall, and grew to a heavy shower. They were glorious drops that made that shower; for the sun shone, and every drop was a falling gem, shining, sparkling like a diamond as it fell.¹

“That is what it is,” said Reepicheep. “Drinkable light. We must be very near the end of the world now.”²

Then the angel showed me the river of the water of life, bright as crystal…³

The Physics of Beauty

The kaleidoscope of water and light interactions primarily arises from the optical properties of reflection and refraction. Light reflects from water to a greater or lesser degree, depending on the angle between the ray of light and the surface of the water. A ray incident on the water perpendicular to the surface will only reflect about 3 percent, but as the angle of the incident ray of light becomes more nearly parallel to the surface of the water, reflection becomes almost 100 percent. 

Refraction occurs for light rays that penetrate the surface of the water. Water has an index of refraction about 30 percent greater than air, which causes a distinct bend in the ray’s direction at the surface. The bending or refraction effect increases for colors towards the blue end of the visible spectrum, so that the blue and violet colors refract more than the reddish colors. Now, at about this point, a physics explanation begins to wane in suitability for dinnertime conversation, but the so-called chromatic dispersion leads to some much-appreciated optical phenomena. 

A rainbow, with its spectrum of colors arching across the sky, stands out as perhaps the most striking example of beauty in the interaction of water and light. The rainbow’s colors arise from sunlight undergoing refraction at the surface of a nominally spherical raindrop, followed by internal reflection at the opposite side of the drop, and additional refraction of the light as it exits the drop. Dispersion causes the different colors inherent in sunlight to refract at different angles, causing us to see the bow with red at the top or outer edge of the arc, and violet at the bottom or inner edge of the arc. Dewdrops on grass glistening in the morning light allow us to see just one color of a mini-rainbow emanating from a single drop.⁴

A Remarkable Absorption Window

Pure water is clear, but it is most transparent for blue-green wavelengths of light. The color of a body of water arises primarily from reflecting the sky, leading to the changing appearance of a lake or ocean view with the time of day and weather conditions. The clarity of water in the visible part of the electromagnetic spectrum is especially dramatic when considering water’s absorption coefficient as a function of frequency. On either side of the narrow visible spectrum, water absorbs between 10 million and 1 billion times more strongly than it does for the colors of light that we can see. This remarkable absorption window, originating from the energy levels inherent in water molecules, not only allows us to see but enhances the beauty of what we see.⁵

In the expression of Francis Bacon, “The whole world works together in the service of man.”⁶ The finely tuned attributes of water and light that allow life to exist are well documented.^7,8 For humans, however, life is about more than just being physically alive. Our sense of beauty, as perceived in the interaction of water with light, brings to us a joy that heightens our experience of life. Intelligent design is seen not only in natural phenomena that have a low probability of happening by chance, but also in masterful strokes of design, providing beauty and aesthetic enjoyment from nature’s palette to refresh our spirits and enchant our hearts.

Notes

1. George MacDonald, What’s Mine’s Mine, (Eureka, CA, Sunrise Books, 1994; Kegan Paul/Harper, 1886), 394.
2. C. S. Lewis, The Voyage of the Dawn Treader, (New York, HarperCollins, 1994, 1952), 229.
3. Revelation 22:1 (ESV).
4. David K. Lynch and William Livingston, Color and Light in Nature, (Cambridge University Press, 1995).
5. John D. Jackson, Classical Electrodynamics, 2nd ed. (New York: John Wiley & Sons, 1975), 290–291.
6. Francis Bacon (1561–1626). The Wisdom of the Ancients. 1609; https://www.bartleby.com/lit-hub/of-the-wisdom-of-the-ancients/xxvi-prometheus-francis-bacon-15611626-of-the-wisdom-of-the-ancients-1857/ .
7. https://evolutionnews.org/2020/04/michael-denton-explore-the-miracle-of-air-and-sun/.
8. https://evolutionnews.org/2020/02/wonder-of-water-michael-denton-at-bridalveil-fall/.