Plasma and Magnetic Fields in the Solar System

I am planning to talk about the interplanetary gas in the inner part of the solar system, in which we live. I should like to discuss the circumstances that we shall find when we send up suitable instruments to investigate that gas. The subject is the counterpart to meteorology on the earth; we shall be concerned with the permanent and the variable features in the gaseous content of the inner part of the solar system. We first ask, what will be the experiments equivalent to the meteorological measurements of temperature, pressure, and wind? What are the quantities we should be interested in, and what are the orders of magnitude that we now expect we shall find?