The meniscus of mercury in a glass capillary tube is convex because of the very high density of mercury as compared with water the low surface tension of mercury the greater attraction of mercury atoms to the glass than to each other the weaker attraction of mercury atoms to the glass than to each other electrostatic repulsion between the glass and the mercury

The meniscus of mercury in a glass capillary tube is convex because of its high cohesion property where mercury stick together rather than spread to the tube compared to the water. The cohesive force is mutually attractive to each other, resulting to electrostatic repulsion to the tube.  Moreover, Mercury creates a solid-like state due to surface tension and low adhesion to the tube. 

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers