Air molecules around us push down on us all the time. That is air pressure. In weather, there are two types of pressure systems: high and low pressure systems. In this post, we are focusing on high pressure systems. High pressure systems mean that a lot of air is pushing down on a certain area. High pressure systems happen when air from the center of the system sinks down towards the ground. It sinks because it is more dense than the air below it, so it sinks. This pushes away clouds and provides us with sunny weather. This also leads to dry conditions because the air going down pushes away the moisture too. That is what high pressure systems are!