The Great Journey in Photography

They Say Its the Smog….


300mm f4.5 200iso 1/1,250sec

They say it’s the smog that makes Southern California sunsets so spectacular. Kind of makes sense, we all think of smog as a toxic mix of various deadly chemicals. It is easy to think of these chemicals being a myriad of colors and luminescent gasses reacting with each other spewing a gambit of colors. Maybe those molecules are represented by the colors of the periodic table give that impression, it’s easy to imagine. We all know that light illuminates color in objects especially transparent ones. Take a thick layer of smog, put the sun behind it and holy cow, you should get yourself one heck of a colorful sunrise or set. It all makes perfect sense.

As I learn more about light and how it behaves I started to think maybe there is just a little more to it than that. As it turns out, the whole line of thought is false. First, lets take a look at what it is that makes sunrises and sets more colorful in the first place. During these times (the golden hours) the sun’s light rays travel throughout the longest distances of the earth’s atmosphere. Light is made of different size wave lengths presenting different colors of the spectrum. The blue or cool side being the shorter, weaker waves. As these rays of light encounter obstacles, for example an oxygen molecule, the shorter waves of the blue spectrum get stripped away and scatter off into the atmosphere. This is also why the sky is blue. When it happens the intensity of the light ray decreases and visually light becomes orange/red and more saturated. Those orange and red charged light rays are what causes the vivid colors. Contrary to the myth, large particles of dust and pollution block too much of the light and colors tend to become muted and very low in intensity. In a spectacular sunrise or set the unadulterated light generally does not illuminate other colored objects but rather reflects off of objects like water and clouds.

How that light gets to these object is also important. Higher clouds like cirrus tend to show the most vivid colors. This is because the portion of the atmosphere closest to the earth’s surface known as the boundary layer contains most of the dust, haze and pollutants. Its density tends to dull the colors and lower the intensity to the point that lower clouds are not as vivid. In fact the very best light is those rays that pass just above the boundary layer and reflect off the higher clouds. This occurs just before or after the sun is in view. That gives credence to the saying “start early and leave late”.

Saying “its the smog that makes the sunsets so great” is just fine for the movies but in real life it is just not true. Lets give the myth its last rites and bury it for good.

Thanks to everyone who stops by. Until next week Happy Shooting.

One response

  1. I like all of the colors.

    September 28, 2012 at 7:11 am

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