Arizona Sunsets

Arizona Sunsets

In Arizona sunsets and sunrises seem to happen more often. Nice big colorful ones. I spent a couple weeks camped about halfway between Los Angeles and Phoenix, and the sunrises and sunsets were incredible.


Arizona Sunsets
A Sunrise

Why do Sunsets happen anyways?

When light travels through empty space, it’s rays continue unchanged. While traveling through air (or anything), sometimes those rays hit little particles and get deflected. As you may remember from elementary school phsyics, sunlight is made up of basically 7 different colors. Those different colors of light travel as separate light waves. The waves of certain colors of light – mainly blue and violet – get deflected easier than others. (This causes the sky to look blue)


Arizona Sunsets
A Sunset

The more atmosphere light travels through, the more particles there are for the blue and violet light to get deflected.  When the sun is low near the horizon, it’s light has traveled through more atmosphere.

Let’s say a person was a the bottom of a REALLY deep and wide hole. One that goes many miles below sea level (but is not full of water). Well, the light getting down to the bottom of that hole would contain less blue and violet, because it would’ve gotten scattered on the way down and made the sides of the hole look more blue than they actually are.

The earth’s atmosphere is VERY thin compared to the size of the earth. Most of the air is within 10 miles of the earth’s surface. The earth’s diameter is over 7,000 miles. Since it’s so thin, there is a big difference in how much air the sun’s rays travels through when the sunlight is shining straight down onto a certain point of the earth vs. where it shines close to tangentially through the atmosphere near a surface (as it does wherever on earth is experiencing a sunrise or sunset.

The picture below illustrates this well. Note that the thickness of the atmosphere is greatly exaggerated to help illustrate. In reality, since the atmosphere is much thinner than shown, the difference in paths is is actually much greater than what’s shown. I don’t want to do the math but at sunset, that “long path” is probably 100 times longer than the “short path” at noon.

From a post

That cause two things:

1 – The “Golden Hour” – where light (and everything it shines on) is more warm (yellow/orange/red) in the last hour or so before sunset. This is because some of the blue and violet light is not reaching you. It’s getting deflected and making the sky (and the earth) more blue to the west of you.

2 – The clouds get colored. Normally they are white and grey. Because they are actually white and grey. They are not opaque (they’re like pockets of mist), so they get illuminated by the sunlight. Since the light coming in at sunset is warmer colored, that’s all there is to light up and reflect off the clouds.

Why are the sunsets better or more frequent in some places

I spent many months on the California coast this year. When a big sunset happens, it’s extra nice because it reflects off the water. But they don’t happen often. A bit west, in Arizona, they happen much more often. The sun is still shining through the same distance of atmosphere. So why are there more in Arizona?

It depends mostly on just having clouds to light up.  And on having the right kind of clouds.  Light, thin, fluffy clouds like in the picture well below are lit up best. This is impacted by a lot of complicated things and there are some places that just get more cloudy, or that get more cloudy in the evening. This makes more difference than anything else.

Something else that may make a difference (though I don’t know how much – maybe it’s negligible) is local pollution. Let’s say you’re a the beach in Los Angeles. Looking out west, the air is fairly clean. Now let’s say tomorrow you go 100 miles east of L.A.. Looking west, the air is full of shit that got spewed out from the city. All that crap deflects more blue and violet light.





    Lovely photos. Yeah! Arizona has great sunsets in the winter when those of us in the northern climes are clinging to our wood burning stove and it’s dark out…really dark, and cold, and like freezing outside.

    Nothing like the southwest in winter. Happy Travels.

    A blog post titled “Arizona Sunsets” – I’m expecting pictures of beautiful sunsets. And I wasn’t disappointed. But then you explained sunset science. Clearly this is a blog to keep an eye on. Awesome. Got me RSS’d now.

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