One of the interesting things to look for: Dust, ash, etc. Once in awhile, forest fires, volcanoes, etc can deposit ash etc along with Precip... sometimes it floats on the top, sometimes sinks to bottom, if you observe that, might enter description, color, etc, in the observation comments. That info is also used!
Another thing to think about... meteorite dust... ever try a small magnet when you empty your tube?
Might have a surprise once in awhile! A lot of that dust in your domicile's gutter is magnetic,... from space,...