A sun meter having a processor receiving a signal from a photocell. An apparatus for the separation of a particulate-fluid suspension can include an enclosed vessel having two or more sections disposed coaxially along a common longitudinal centerline, wherein a first section has a first cross sectional area, and a second section has a second cross sectional area. The bottom edge of the main panel is joined to the top edge of a padded waist band and the bottom edge of a head restraining panel is joined to the top edge of the main panel.