• The plastic of the sidewalls is prob'ly mildly hydrophobic. So, the cohesion of the water to itself is greater than its adhesion to the plastic.

    Do I still measure from the meniscus?

  • I think it’s because of the setup, trying to display the 3 dimensional concept in 2 dimensions. There two panes holding the front and back relatively close, so the capillary effect is more prominent in that plane.

  • Because the liquid has a high viscosity and has just been filled to that point, taking longer to rise to the walls than internally due to increased friction.

    (Just one of a million possible explanations if no further context is provided about what we’re looking at.)

  • Whether the liquid on the sides climbs up or dips down is based on how hydrophilic or hydrophobic the surface is. Some materials will have basically none, some climb a lot, some dive down a lot. Glass is pretty highly hydrophilic, so it climbs, giving us the behavior we're "used to". The plastic is probably mildly hydrophobic.