Needed: Brighter Air

I’m wondering if they can change air so that it becomes brighter.  I guess it would contain some kind of molecule that would hold or reflect light.

One application:  making the atmosphere brighter, so as (perhaps) to reflect sunlight and reduce global warming.  Another application, especially for a biodegradable, light-sensitive, or timed product:  pump it out in the city so as to reduce the need for streetlights.  Especially if you could make it heavy, so that it would tend to settle in the bottom 10-20 feet of the atmosphere, and not outside of people’s high-rise apartment windows.

It could also be handy in the home, at night, in place of energy-consuming nightlights.  Or maybe they could make light-producing streets and highways, such that natural dust or humidity would pick up the light and, again, reduce the need for streetlights and headlights.  Safer for nighttime bicyclists, too.