6
$\begingroup$

I've noticed that sunrises are not reverse sunsets regarding the sky hues and lighting.

Sunrises always start pinkish and end with a glorious yellow sunshine. On the other hand as the sun sets lighting gets orange and the sky gets a hellish red colour. I've noticed this many times regardless the weather or temperture.

Why is this contrast between colors (pastel-like in the morning vs vivid in the evening) in a fenomenon that should be same in both instances in a day ?

Am I the only one that perceives this difference ?

Improve this question
$\endgroup$
6
  • $\begingroup$ I'd always thought it was the amount of pollutants put into the air by manmade and natural processes during the day. I'd be interested in the answers. $\endgroup$
    – BillDOe
    Oct 11, 2018 at 20:57
  • $\begingroup$ Two links. $\endgroup$
    – Lucian
    Oct 11, 2018 at 23:50
  • 1
    $\begingroup$ @Lucian "During the night, winds die down, smog-producing urban activity eases and the atmosphere cleanses itself. The dawn is clearer than any other time of day." I'm sceptical that the atmosphere "cleanses itself" overnight. I could believe that the wind blows pollution elsewhere. As for adaption of our eyes, Google image searches for sunrise ... $\endgroup$
    – Keith McClary
    Oct 12, 2018 at 4:13
  • $\begingroup$ ... and sunset. The camera doesn't lie (although the photographer may photoshop). $\endgroup$
    – Keith McClary
    Oct 12, 2018 at 4:14
  • $\begingroup$ This is likely on-topic here, but it's probably also on-topic in Earth Science SE as well. Have a look around there and see if there is anything that addresses your question. $\endgroup$
    – uhoh
    Oct 12, 2018 at 4:43

1 Answer 1

Reset to default
5
$\begingroup$

You are not the only one whom sees a difference but remember that the statistics are skewed. Fewer people are awake early to see, or photograph, the sunrise while more people are awake to see the sunset.

People and heating of the Earth are factors explaining the difference in the atmosphere through which the sunlight is filtered, that affects the appearance of the light.

It's well explained at our Photo.SE site:

Most of the physical reasons (I can think of) probably do favor sunsets as well. During the day, the sun is heating the air and the ground. This leads to air movement that tends to pick up particulates (e.g., dust, smoke, etc.) and keep it in the air. It also leads to water evaporating (relatively) quickly from anything like lakes and rivers in the area. In addition, quite a few things that people do (e.g., driving) tends to happen primarily during the day, so it "pushes" more pollution into the air during the day. Thus, at the end of the day, the light is shining through air that carries more particles, which almost inevitably does more to diffuse the light.

During the night, there's a lot less pollution being put into the air, and the lack of heating means the air tends to be calmer as well, so by morning many of those particulates will have simply fallen out of the air, and the humidity either formed into clouds or precipitated. The clearer air does less to diffuse the light, so the sunrise isn't as spectacular.

A more scientific, but not complicated, explanation is offered at Wikipedia's "Sky" webpage. The heat affects the Rayleigh scattering and the Lorenz–Mie–Debye solution or Mie scattering, that explains the differences between sunrise and the sunset - a difference in the number and movement of particles in the sky.

A somewhat related factor is explained in a Q&A over at Space.SE: "Where does space begin on planets without atmospheres?". The height of the atmosphere and its layers along with the distribution of its component gases is altered by the heating of the planet and atmospheric circulation.

Improve this answer
$\endgroup$
4
  • $\begingroup$ I view that quoted material as rather speculative at best. But let's just compare sunrise and sunset as viewed from the top of a very small island, so both are seen over nothing but ocean. $\endgroup$
    – Carl Witthoft
    Oct 12, 2018 at 15:54
  • $\begingroup$ Actualy i was a student cook at a hotel away from town on an island with early morning shifts. And every time in my life i ever saw the sunrise and sunset was always on the countryside. That's why I asked the question in the first place. $\endgroup$
    – Demis
    Oct 13, 2018 at 16:43
  • 1
    $\begingroup$ @Demis - Nice to have a job in paradise. The effect of the Sun heating the ocean also causes a difference, though to a lesser extent than highly populated areas. The technical explanation offered at the bottom of my answer, which I thought goes beyond the scope of the question, explains (proof in the links) that it's only in the desert (where population and industry is sparse) that the sunrise and sunset are the most similar; heating sand doesn't have as great as an effect but the heating does increase the turbulence of the atmosphere above. $\endgroup$
    – Rob
    Oct 13, 2018 at 16:55
  • $\begingroup$ @carlwitthoft , The optical difference of land versus sea sunsets are a condition of the question which has been forgotten. Sunset colors are almost entirely defined by atmospheric mineral and other chemistry and air temperature, so that sunsets in volcanic regions can be very rainbow-colored. In the UK it's "red sky at night, shepherd's delight", in the Mediterranean, it's "the sky is bright purple, it will be 37'C tomorrow" $\endgroup$
    – bandybabboon
    Oct 16, 2018 at 3:21

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .