Cloud Colours

[jennyberki]

This is something I have wondered about for a while. Why do clouds vary so much in colour? I'm talking about the white/grey/black spectrum here, not the various effects you can get due to lighting conditions such as sunrise or sunset.

Is a black cloud just thicker than a white one? Or is it lower? Or does it contain different types of precipitation?

[SnowBear]

I would say all of the above.

Thickness of cloud, angle of the sun, type of precipitation within, density of that precipitation, the shadows from other nearby clouds, all contribute.

[Chris Knight]

I would say all of the above.

Thickness of cloud, angle of the sun, type of precipitation within, density of that precipitation, the shadows from other nearby clouds, all contribute.

And colour of the terrain or water below - particularly if the cloud contains ice, which is reflective, rather than water droplets which are more dispersive. Hence snow clouds may appear brownish over suburban areas, or greenish over grassland.

[Stratos Ferric]

And colour of the terrain or water below - particularly if the cloud contains ice, which is reflective, rather than water droplets which are more dispersive. Hence snow clouds may appear brownish over suburban areas, or greenish over grassland.

Reflection may play a small part, particularly at night, however depth and composition are the main determinants. Snow laden skies can often, by repute, have a yellowish or coppery tinge (and I have seen this myself), particularly stratus - ask not why; rain clouds by comparison tend to be steely.

The other main factor is whether the water in the cloud is liquid or frozen. Cumulonimbus and the tops of towering cumulus tend to look particularly white because they are frozen at the top.