The Friends of the Wild Flower Garden
Published in The Fringed Gentian™ Autumn/Winter 2019 VOL. 67 No. 3
by Diana Thottungal
This photo was taken on a cold day with lots of ice crystals high in the air. Like snow, ice crystals tend to have hexagonal shape, but, being composed of clear ice, act like prisms and break up the light. The reason they’re called “dogs” is because they’re paired, one on each side of the sun.
Nothing to do with the planet Venus, this phrase refers to the pinkish glow just above the horizon. It shows up just a bit after sunset or before dawn, and, since it can be seen as a band, unlike a sunset cloud, it gets called a girdle. It’s pinker and stronger in the winter, which makes it a nice winter nature event for those of us who prefer dawn to be later in the day. In mythology, the girdle of Venus, who was also know by the ancients as Aphrodite, was considered magical and inspired love.
On the night of November 8-9 of 2003 there was a total eclipse of the moon. It’s no surprise that the bright full moon - it’s always a full moon when there’s an eclipse - gets darkened. The surprise it that it grows red. Wherever does that come from? The Earth in fact is responsible. During totality the only light reaching the moon has passed through the Earth’s atmosphere and gotten bent as happens with a prism. All that’s left to reach the moon is the red part.
Those are cirrus clouds (the very high, sort of wispy ones) covering the sun and they give that impression, but, if you look carefully, there are a handful of sunbeams radiating out from the sun in the lower half of the picture. And there’s even a tiny sundog. In the upper left. But the parallel white areas are those cirrus clouds aligned with the wind direction at their high altitude.
This lovely rainbow was spotted over the Garden in May of 2006 by Garden Naturalist Jodi Gustafson. Rainbows are magical enough all by themselves, but look again…there are two! And the sky between the two is darker than the sky on either side. Even more…the colors are reversed in the second (dimmer) rainbow. What’s going on is that below the lower arc is where the sun is setting behind the person looking at the rainbow, so it makes sense that the sky is brighter. But what about between the bows? Where did that light go? Away!
The bright rainbow is water droplets acting like prisms. The darker area between gets its own name, Alexander’s band, and it is just that, the area where the light is escaping and not being reflected back to you as the viewer.
The reversal of colors in the dimmer rainbow is the result of the fact that the little raindrop prisms reflect the light twice, giving off a mirror effect. Another tidbit to think about is how much brighter the right side is than the center.
If you Google rainbow photographs, you can see that having one end brighter than the middle is not an infrequent occurrence. It may be the source of the “pot of gold at the end of the rainbow” legend, although that is usually attributed to the rainbow technically not having an end, since it is actually a circle cut off by the land.
Diana Thottungal is a retired Garden naturalist.