Only a short beach walk today, as we left early to explore the wonders of Cayo Costa State Park. Incredible shelling, and lots of live animals including blue crab, sand crab, mole crab, living whelks and Florida fighting conch. We also saw a turtle nest that had been raided by a group of ghost crabs. It’s a rough world out there for baby turtles.

I managed to grab some amazing sunrise photos before my walk ended.

Like a rainbow, a sunrise (or a sunset) is a beautiful example of the deep mystery of color.

Sunrises are orange because white light from the Sun is broken up by our atmosphere. Any sunbeam is actually made up of myriad photons, or pieces of light. Each piece has its own wavelength. Blue and violet photons have tiny wavelengths, while orange and red photons have longer wavelengths. The oxygen and nitrogen in the air are more likely to interact with the shorter wavelength photons, sending them bouncing off in all sorts of crazy directions (that’s why the sky is blue!) At Sunrise, the beam we see has passed through all the air over the Atlantic, so that most of the short wavelength blue and purple photons have been scattered out. What’s left are the longer photons, which we see as orange.

But there’s the real mystery. There’s nothing inherently “orange” about an orange photon. It’s just a wavelength. What makes the photon orange is that it excites one kind, but not another kind, of light-sensitive cell in our eyes. In a certain sense, the sunrise isn’t orange (the experience of orange) until you look at it.

Why, though, do we see in color at all? Why those beautiful blue skies and emerald green water I can see from the beach? Why red flowers, yellow bananas, and, well, orange oranges? Why isn’t the world, like 1939 Kansas, all in black and white?

dorothy and toto

Our ancestors were fruit eaters. Being able to spot the ripe mango or strawberry or blackberry might have given us a selective advantage. But another theory I recently ran across is that we evolved our color vision to help us read emotions.

The idea is that a potential rival (or a potential mate) will show you their feelings in their changing skin tones. A blush, a flash of anger, or a moment of fear can all show up on our faces, and our exquisite color vision seems to be especially tuned to these subtle color variations.

doroth angry

So when you enjoy your next sunrise, consider for a moment that you might be doing so because you’re so good at knowing when that cutie across the room is flirting with you!