Meniscus

A meniscus (derived from the Greek " Meniskos " = Half Moon ) is a bulge in the surface of a liquid. It can be concave and convex menisci are distinguished (see figure); both go on the interaction between liquid and surface of the adjacent wall back:

• Concave menisci (Fig. A) arise, for example between water and glass. Concave menisci in fine structures lead to capillarity. When reading a scale for measuring the level of liquid in these menisci can be read at the bottom.
• Convex menisci (Fig. B ) occur for example when mercury barometers; they are read from the top.

Factors

The contact angle of the meniscus surface of the wall is determined by the three interfacial tensions and often also subject to hysteresis. The curvature in the further course is proportional to the local pressure differential see Young-Laplace equation. In weightlessness, the curvature between homogeneous phases of the meniscus is constant, that is spherical. In a gravity field, the surface is far from the horizontal wall, wherein the width of the transition depends on the Wichteunterschied between the fluids.