AST 102 Lecture Notes - Lecture 16: Fear Mongering, Short Circuit, Small Appliance
Document Summary
A common way to show the overall properties of an atmosphere is to build a plot that shows both temperature and pressure as a function of altitude. We will be looking at quite a few such plots in the coming weeks. Here is an example of one such plot for the modern terrestrial atmosphere. The present atmosphere of the earth is nothing like its original atmosphere. There have apparently been three main stages in the evolution of the atmosphere. The first, or original or primary or primeval atmosphere was mainly molecular hydrogen, plus some helium, and traces of other gases. The hydrogen and helium escaped because the earth is not massive enough to retain them. Recall that temperature is a macroscopic quantity that is really telling us about the average energy of motion of atoms or molecules in a gas. The actual distribution of speeds (or energies) is called the maxwell-boltzmann distribution.
