Monday, September 12, 2016

Oh, so blue!

When I set my photo processing program to the sunlight setting, it adds a yellow or reddish tinge to everything. Why, then, when the sun shines brightly, are we surrounded by blue?

Taking the dog for a paddle. Saratoga Beach

I switch back to "as shot". Sea and sky play with blue. The reds and yellows can stay on dry land.

Bare rock mini-islet somewhere out in the channel.

The sun sends us white light, a blend of wavelengths, visible and invisible (to our eyes; birds and bugs see things we can't.) The gas molecules in the atmosphere ignore the long wavelength rays, like red and yellow, letting them pass by on their way to land, and grab onto the blues and bounce them all over the sky. So we see the blue everywhere when we look at the sky.

Just before sunset, last February.

Near the horizon the light has travelled further to reach us, and some of the blue has been scattered off in other directions, so the sky looks paler. At sunset, pollutants and salt crystals (over the ocean) filter out even more of the blue.

Quadra Island lighthouse, July. The mountains in the distance are blue, too.

I always thought the sea just reflected the sky. Or vice-versa, maybe. I was wrong. The sea processes light differently. The water absorbs the warmer colours, and rejects the blue, bouncing it back into our eyes.

Rainy day over Tyee Spit. What little warmth arrived in the light that has percolated through the clouds highlights the dry grass.

The evergreens that cover our hills produce aromatic terpenes that form small particles in the atmosphere, and these also scatter blue light, seen better from a distance. (Up close, the trees are green.)

Saratoga Beach, with distant kayakers. Blue sky, blue mountains, blue water. Red kayaks.

Kite, over Tyee Spit last week. Looking almost straight up, the sky becomes deep, deep blue.

Something to ponder: when I look at the water, from the docks, for example, it is usually blue or blue-silver. But if I'm looking straight down into the water, it is often a deep green. Why is that?

A helpful article on this topic is "Why is the Sky Blue?" by Philip Gibbs. Also, see a briefer explanation on Scientific American.

A Skywatch post.


  1. I can't believe how far people stand up paddle. Twice I've seen two people crossing from Lund to Savary Island on boards. The second time it looked like one had a duffle bag on board as well. - Margy

    1. I know. I would be afraid to go farther out than I could swim easily. Island to island; yikes!


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