There's no inherent "benefit" to *any* of these settings, changing their values depends on what you want to achieve, i.e. there's no "better" value except one that is more suited to a particular goal you may have. Their default values are set to generally realistic levels for an average (possibly British, hehe) day. Increasing Bluesky glow will, well, increase the amount of glow in the "bluesky" component. Try turning Bluesky down to 0 to see exactly what that component contributes to the atmosphere. That's really the easiest way to understand it, a text explanation is not as useful as seeing it.
- Oshyan