Introduction to Environmental Physics

Introduction to Environmental Physics
Key concepts, fundamental principles, and typical applications

1. What Is Environmental Physics?

2. Fundamental Physical Quantities

3. Core Physical Processes

3.1 Energy Balance

[ \underbrace{S_{\downarrow}}{\text{incoming solar}} + \underbrace{L{\downarrow}}{\text{downward longwave}} = \underbrace{L{\uparrow}}{\text{upward longwave}} + \underbrace{H}{\text{sensible heat}} + \underbrace{E}{\text{latent heat}} + \underbrace{G}{\text{ground heat flux}} ]

• Solar radiation ((S_{\downarrow})) – primary energy source, varies with latitude, season, and atmospheric composition.
• Longwave radiation ((L)) – emitted by Earth’s surface and atmosphere; controlled by temperature and greenhouse gases.
• Sensible heat ((H)) – heat transferred by conduction and convection.
• Latent heat ((E)) – energy absorbed/released during phase changes of water (evaporation, condensation).
• Ground heat flux ((G)) – conduction into/out of the soil or ocean mixed layer.

3.2 Fluid Dynamics (Atmosphere & Ocean)

• Continuity equation (mass conservation): [ \frac{\partial \rho}{\partial t} + \nabla!\cdot(\rho \mathbf{v}) = 0 ]
• Navier–Stokes equations (momentum): [ \rho!\left(\frac{\partial \mathbf{v}}{\partial t}+ \mathbf{v}!\cdot!\nabla\mathbf{v}\right) = -\nabla p + \rho\mathbf{g} + \mu\nabla^{2}\mathbf{v} ]
• Thermodynamic energy equation (first law): [ \rho c_{p}!\left(\frac{\partial T}{\partial t}+ \mathbf{v}!\cdot!\nabla T\