Red Sky at Night, Sailors' Delight?

Red sky at night, sailors' delight;
Red sky at morning, sailors take warning.

When there are suspended particles and aerosols in the atmosphere at sunset, shorter wavelengths (violets and blues) of the setting sun's light get scattered, while the longer wavelengths (red and oranges) are able to penetrate.  We see a sunset like this one.

Traditionally, the 'red sky at night' sailor's axiom holds, at least in the northern hemisphere, because weather systems tend to travel from the west to the east.  Thus, the dust and water vapor that refract the light are to the east of the sunset, meaning they have passed.  Conversely, a 'red sky at morning' means that the weather system is to the west and therefore still approaching.

In this case, however, the red sunset is not caused by a stormy weather system.   Instead the aerosols and particles in the atmosphere offshore are components of volcano smog -- called vog here in Hawaii.  On days when the winds are calm or relatively light here, emissions from Kilauea, the very active volcano on the southern part of Hawaii's Big Island, tend to settle over the island.  We don't like the vog haze -- it burns our eyes and makes our respiratory tracts congested -- but it does make for pretty and often dramatic sunsets.

Location: Kohala Coast, Big Island, Hawaii