Meniscus (liquid)

A: The bottom of a concave meniscus. B: The top of a convex meniscus.

A concave meniscus happens when the particles of the liquid are more strongly attracted to the container (adhesion) than to each other (cohesion). This causes the liquid to climb the sides of the container. This happens between water and glass. Water-based fluids like sap, honey, and milk also have a concave meniscus in glass or other wettable containers.