Atmospheric Motion

Abstract

The air in the atmosphere is in continuous motion, as the result of non-equal distribution of energy over the Earth’s surface. Different energy distribution, which is manifested by the different heating of the Earth’s surface, creates differences in pressure. The pressure differences produce a horizontal air motion which is known as wind. Atmospheric movement is caused by forces that affect horizontal and vertical movement of air. Dynamic meteorology deals with movements that significantly determine weather and climate (Morel 1973; Ćurić 1983, 2000, 2002 Gill 1982; Holton 2004; Mak 2011; Lin 2007; Markowski and Richardson 2010; Saha 2008; Spiridonov and Ćurić 2011; Ćurić and Janc 2016; Zdunkowski and Bott 2003; Vallis 2017). In this chapter only the basic elements of dynamics of the atmosphere are described. In all these cases, the atmosphere does not need to be studied through the individual molecules that it is composing but can be considered as a continuous fluid medium or briefly a continuum (Hoskins and James 2014). Any point in that continuum will in fact be considered as an elementary volume that is very small compared to the volume of the part of the atmosphere that is subject to interest, but it still contains a large number of molecules. We will always use the term “air particle” when we refer to the characteristics of a certain point of space. The state of the atmosphere is characterized by various meteorological variables (e.g. pressure, temperature, density, etc.). It is assumed that each point of the atmosphere corresponds to one (unique) quantity of these variables. It is assumed further that these variables and their derivatives are continuous functions of space and time.