March 2018: The sky isn't everywhere the same
Many of us are not aware of it, but even within Thailand the blue color of the sky differs.........I try to explain why:
The blue color of the sky is due to Rayleigh scattering. As light from the sun shines down it scatters off of nitrogen and oxygen molecules in the atmosphere. Without this process, the sky would be dark during the day except for the bright sun, moon, and stars. Rayleigh scattering is more efficient for shorter wavelengths. So, even though the Sun provides a full spectrum, blue is scattered more efficiently than the longer wavelengths of light. Thus blue is the dominant color you see.
The color of the sky is the same for most places on the Earth, because the sunlight is relatively constant and the atmosphere is relatively uniform in composition (nitrogen and oxygen). The exceptions are air pollution, high latitudes, and high altitudes since these have similar effects in attenuation of the light; light travels through more atmosphere, and therefore colors change like you see at twilight. Air pollution in particular is a highly variable source of scattering and absorption that gets quite extreme when there are high concentrations of particles. Examples are skies above cities. High latitudes change the geometry, similar to twilight. In contrast, high altitudes have less atmosphere, so if you go high enough (e.g. in a hot-air balloon) there just won't be much scattered light and it will get dark due to the lack of atmosphere.
Thus we can conclude that the blue color of the sky differs a bit per region where you are. I never realised myself untill some people attended me on the fact that the skies in Isan are different blue than anywhere else....... based on above, the rather small airpolution combined with the latitude and altitude is debet to it. Now I know this I look more and more into the sky and enjoy my residence in Isan more every day.
So when you travel around the globe, pay attention to the sky above you and notice the differences