The previous chapters have presented the basics in atmospheric thermodynamics. As we know, in atmospheric sciences the ultimate goal is to predict as accurately as possible the changes in weather and climate. Thermodynamic processes are crucial in predicting changes in weather patterns. For example, during cloud and precipitation formation vast amounts of heat are exchanged with the environment that affect the atmosphere at many different spatial scales. In this final chapter we will present the basic concepts behind predicting weather changes. This chapter is not meant to treat the issue thoroughly, but only to offer a glimpse of what comes next.

Basic predictive equations in the atmosphere

In the Newtonian framework the state of the system is described exactly by the position and velocity of all its constituents. In the thermodynamical framework the state is defined by the temperature, pressure, and density of all its constituents. In a dynamical system such as the climate system both frameworks apply. Accordingly, a starting point in describing such a system will be to seek a set of equations that combine both the mechanical motion and thermodynamical evolution of the system.

The fundamental equations that govern the motion and evolution of the atmosphere (and for that matter of the oceans and sea ice) are derived from the three basic conservation laws: the conservation of momentum, the conservation of mass, and the conservation of energy. For the atmosphere the equation of state relates temperature, density, and pressure.