Does Earth's latitude affect the color of light?

Question

I was talking with a friend about what conditions can affect color, gamma and white balance, and how to get in order these variables into the configuration to set up and get a good shot.

Beside the angle of the sun at some day (we will assume that the time is every the same in every place), and related to the season (but also we will assume that the same season in every place).

Also with the assumption for the same conditions and camera setup in every place...

So, first question:

1) Is there a change in the color or white balance or gamma or something taking one shot for example at tropic, at equator and pole, because the light from sun changes in every latitude?

For example, you get less/more color in equator than in north tropic, and both are different than on the south tropic?

If this is true:

2) Is the difference substantial, for e.g., from Lat 40S to 50N? (This assumption must be without seasons of course. I'm not talking about distances to the sun, so... for e.g. Summer in 40S and summer in 50N, the same day (21-12 for South, 21-6 for North)

3) Can it be corrected?

4) Do I have to take any consideration to set up my camera if I travel from one place to another place?

Answer 1

Latitude doesn't directly change the sun's light in any way. The angle of the sunlight and the amount of atmosphere it has to pass through both indirectly impact the intensity and color of the light, but this shouldn't have a significant impact on taking photos as long as you properly meter and white balance.

The bigger direct concern would be the angle of the light which you simply manually take in to account based on where in the sky the sun is. While the angle impacts the amount of atmosphere and thus the color and intensity, the direction of the light is a bigger concern. Light coming from above lights a scene differently from light coming in from the horizon and the angle the light is coming from impacts how you shoot.

The reason it can seem different is because of the effect of the atmosphere and surrounding terrain on the quality of the light. This is going to be impacted in a small part by latitude but is going to be much more dependent on season and weather conditions.

The way to correct for changes based on the day and weather is to use a grey card (or really any piece of white or medium grey paper can work) to manually set the white balance for the image. A full professional grey card can also be used in post to adjust for contrast/brightness/white balance/etc.

The shooting habits and techniques shouldn't change from one location to another. Even going from indoors to outdoors has fairly little change in how you assure good color, you just have situational techniques that you use based on criteria (such as if the shadows are too strong, use a fill light, or if the colors of the light don't match, use a filter to match them if possible).

Some situations are more likely to need a certain technique than others, but for the most part, light is light and you deal with it the same regardless of source. Which is to say, you deal with it based on conditions.

Answer 2

The color of sunlight reaching the surface changes based on the thickness and quality (in terms of things like particulate matter and water vapor suspended in it) of the air it passes through. Whether the sun is at an angle 30º above the horizon because it is noon in winter at a high latitude or because it is 4 p.m. in the tropics doesn't make much difference if both locations are at the same altitude. When the sun is at a low angle in the sky, such as when setting or rising, the rays must travel through much more atmosphere than when at higher angles in the sky. The condition of the air those rays are passing through can have a dramatic effect on the quality of light that reaches the surface.

The seasons affect the light for a particular location because the amount of moisture and particulates in the air will vary from season to season in many locations. If a place is outside the tropics then the maximum angle of the sun in the sky is lower in the winter than in the summer. This difference increases dramatically as you approach the arctic circles.

In places that have snow covering the ground in the cooler months, the light reflected from the snow will look much different than the same light reflected off of lush green meadows which will look different than the same light reflected off of urban concrete, a sandy beach, or a dusty desert - even when the sun is at the same angle in the sky.

Which of the above factors is most influential varies with the situation as well. In the middle of the Sahara desert, the atmospheric conditions do not vary that much, so the angle of the sun is normally the largest variable - at least until a dust storm develops. In the Pacific Northwest of the United States, cloud cover is highly variable and can potentially be a greater influence than the angle of the sun. There's not much difference between overcast at noon and overcast two hours before sunset. Above the timber line on an exposed Rocky Mountain peak the light will be much different than descending just a few hundred feet into a lush forest of green.

You can always correct for the differences in the temperature and amount of light using colorimetric tools and varying the exposure value. But why would you want to make every place you go look exactly the same?

Does Earth's latitude affect the color of light?

Only indirectly, as the latitude determines the sun's angle in the sky for a given time on a given day, and also influences weather related environmental factors such as atmospheric contents and ground cover.

Answer 3

Ok, here are the answers to your questions one by one

1) There is a change on the color or white balance or gamma or something taking one shot for example at tropic, at equator and pole, BECAUSE the light from sun changes in every latitude?

Yes, absolutely, but the difference is not more substantial than the difference between seasons or time of day.

2) Is the difference substantial, for e.g., from Lat 40S to 50N? (This assumption must be without seasons of course. I'm not talking about distances to the sun, so... for e.g. Summer in 40S and summer in 50N, the same day (21-12 for South, 21-6 for North)

Not more substantial than the difference between seasons or time of day.

3) Can be corrected?

Yes, you can use a gray card

4) I've to take any consideration to set up my camera if I travel from one place to another place?

Do you change your camera settings between morning and evening? do you change your camera settings between summer and winter?

And, most important, do you want to completely compensate for the light? sunset is orange, when I take a sunset picture I want to show this and not compensate for the light color balance - if you always set your camera "correctly" you will have pictures that all look alike.

Answer 4

Okay, it is a little primitive, but it's the easiest way I know to illustrate why the Sun's light gets warmer as its angle in the sky is reduced. When straight overhead, the light rays from the Sun travel through much less atmosphere than when the Sun is on the horizon.

This is the primary reason that both the Sun's intensity and color are affected by the angle of the Sun in the sky. Atmospheric conditions in the portion the rays travel through to reach a point on the ground are also a huge variable in how the Sun will appear to a surface observer. The density of particulates (mainly dust), water vapor, and condensed water (clouds) will absorb and reflect a portion of the Sun's rays that pass through them.

Answer 5

The most significant difference is the dynamic range required to capture the sun areas and the shadow areas. The colour temperature you always have to manage, no matter what, but the dynamic range can be hard to manage, because the light in e.g. California vs Denmark can be the difference between being too hard without shooting HDR in California, vs being fine with shooting raws in Denmark. I've also had some discussion with jrista about some cloud images I took at noon in a winter day in Denmark, and they looked like clouds near sunset at other locations.