Oregon has one of my all-time favorite things in the world. I’ve found them all over the country, but the best I’ve ever seen were here. Songs have been written about them and they have even been considered to bring good luck. The most famous of those songs was sung by Judy Garland. I’m sure you already figured out what I am talking about. It’s a rainbow. Even Kermit the Frog sang about the “Rainbow Connection.” Why are rainbows so fascinating? I think it’s because they are not only beautiful, but they seem magical. They hang in the sky and can disappear just as fast as they appear. I’m sure many of you remember the acronym you learned in school to remember the order of the colors in a rainbow “ROY G BIV” representing red, orange, yellow, green, blue, indigo, and violet.
There is a story behind how I discovered that rainbows are more radiant here than anywhere else I have lived. In August 1998 my mother, who was living in Oregon at the time, died and we flew her body back to Rochester, NY to be buried in the Mausoleum where my father was buried eight years before. While driving around the city where I spent 19 years of my life we drove through a summer rain storm and as it dissipated there it was. A beautiful rainbow in the sky and even a small piece of a secondary rainbow above it. I commented to my wife that it looked funny, kind of dirty, compared to the rainbows I have seen in Oregon. That’s when I asked myself the big question. Why are the colors drab and seemingly smeared so you have trouble distinguishing the seven bands. The answer will follow a short primer on rainbows.
Rainbows seem to be a mystery, but I’d like to let you in on the story of how they are “born.” It takes a few elements to form a rainbow and most of them are obvious. There must be sunshine and you need clouds producing raindrops and, of course someone to see it because after all it is an optical phenomenon. The arrangement of these elements is what makes the rainbow seem so miraculous. The sunlight has to come from behind you and the rain falling in front of you and a favorable sun angle. The light rays penetrate the individual raindrops, and refract (bend) as they enter, hit the back of the raindrop and are reflected back out. That makes what is known as the “primary rainbow.” When the sun angle is right the light can refract or be bent twice forming a “secondary rainbow” above the primary bow. The color order is reversed on the secondary bow with red being on the inside and violet on the outside. If the light is bent three times an even more rare phenomenon forms called a “tertiary rainbow” which is seen above the secondary bow and is much closer to the sun. I have been lucky enough to see a tertiary rainbow twice in my lifetime so far.
Let’s go back to my rainbow sighting in Upstate New York. The question is what made the rainbow look “funny?” The answer is much simpler than you might imagine. The air in Rochester, NY contained much more pollution than we have here in Western Oregon. I theorize that the pollution acts like an opaque filter between the reflected light off the raindrop and my vantage point.
The strangest looking rainbow I have ever seen occurred here in Eugene. When we first moved to Eugene in 1992 we rented a home in South Eugene. One day I was stepping out of my house through the front door and I saw a rainbow off to my left. The colors on the right side of the bow were bright and crisp while the lower third of the left side looked kind of “fuzzy.” I had never encountered that before and it took a minute to figure it out. What made the left side “fuzzy” was drizzle. Those drops are much smaller averaging under 0.02 inches in diameter as opposed to raindrops which can reach up to 0.25 inches in diameter.
The rainbow has been seen as a symbol of hope and as quoted in Genesis “ a covenant between God and every living creature.” Many African and Native American tribes saw the rainbow as a giant and deadly serpent. The Shoshone Indians explained hailstorms by believing the rainbow was a serpent scraping its back on the ice dome of the sky chipping off pieces of ice which would fall to the ground in the form of hail. The ancient Greeks believed the rainbow, called Iris, was a messenger of the gods who bore news of war and death. We’ve all heard the stories of Leprechauns guarding their pot of gold at the end of the rainbow. The problem with that legend is that there is no end of the rainbow. They are actually formed as circles, but the horizon gets in the way. If you are lucky enough to see a rainbow through the window of an airplane in flight you can see the complete circle since there is no horizon in the way.
When I was still working as a TV Meteorologist in Eugene I had a viewer call me asking if what he saw was a rainbow or not. You would think what you would see is either a rainbow or it isn’t, but this is an unusual situation. The viewer told me he was driving a rental car one night while on vacation in the nation’s midsection when he saw what looked like a rainbow except it was white, actually in shades of gray from bright white to a lighter shade of gray. He noted that there were no clouds in front of the moon which was almost full. Well…was it a rainbow or not? It most definitely was a rainbow, also known as a moonbow. The light of the nearly full moon was bright enough to produce a rainbow, but because it is in the dark of night his eyes could only see it in black and white.
As you might remember from your high school biology class, we have rods and cones in our eyes to discern colors. At night, or just in low-light situations, we only see with the rods and they produce monochromatic (one-color, black and white) vision. The cones produce the colors in vision, but they don’t function well in low-light or dark situations. If he could have taken a time-exposure picture of the rainbow with a camera the colors would show up because the camera can be adjusted to compensate for the low-light situation.
Rainbows can be seen in the splash of waterfalls. Niagara Falls in particular can produce some spectacular rainbows. Did you know that you can make your own rainbow? I’m sure you have done it but don’t remember because you were busy at the time. All you need is a day when you can be in direct sunshine and a garden hose. Turn the hose on and have it set on a fine mist spray. Stand with your back to the sun and the spray well out in front of you so it’s not in your shadow. There you have it. You’ve made a tiny rainbow of your own.
What makes the rainbow unique is that each rainbow you see is your own personal rainbow. Since it is an optical phenomenon nobody else sees the exact same one unless they can look through your eyes at the same time as you do. I see it as a God’s gift to each of us to know that it belongs to only you.
Suggestions for future column topics are welcome. Let me know what you would like me to talk about or explain. You can email me at: [email protected]