ABSTRACT
The plasma state here on Earth is quite unusual and exotic but it becomes very common in the outer layers of the atmosphere. It was the development of radio that led to the discovery of the ionosphere, the natural plasma roof above the atmosphere, which bounces back radio waves and sometimes absorbs them. Much of the universe consists of plasma such as our own sun (Figures 3.1 and 3.2), which is a glowing ball of hot hydrogen plasma.
