Chapter 1. Introduction 1.1 Atmospheric Continuum –Continuous fluid medium –“mass point” = air parcel (or air particle) –Field variables: p, , T and their derivatives (all continuous functions) 1.2 SI Units –SI base units: m, kg, s, K –SI derived units: Hz, N, Pa, J, W –Exception: mb=10 -3 b  1mb = 100 Pa = 1hPa –p SL = 101,325 Pa = mb

1.3 Scale Analysis Estimate the significance of various terms in the governing equations –Magnitude of field variables –Amplitude of their fluctuations –Characteristic length and time duration of fluctuations Examples of horizontal scale sizes: Table 1.4

1.4 Fundamental Forces Laws of conservation of mass, energy, and momentum govern the motions of the atmosphere Fundamental forces –Pressure gradient force –Gravitational force –Viscous force (important only in boundary layer) Apparent forces (due to Earth rotation) –Centrifugal force –Coriolis force

Fundamental Forces

Fundamental Forces cont’d

x-stress ~ z-gradient of u

1.5 Noninertial Reference Frames

1.5.1 Centrifugal Force

1.5.2 Gravity Force

1.5.3 Coriolis Force

Cartesian Components of F Co

Horizontal Component of F Co Toward the right of U in northern hemisphere F Co U k

1.6 Structure of the Static Atmosphere

Hypsometric Equation

Geopotential Height Z

Generalized Vertical Coordinate

Pressure as a Vertical Coordinate