1. What Causes the Wind? Newton’s Second Law F = ma

2. Forces Involved Pressure Gradient Force Friction (2 types for fluids) – Molecular viscosity (random motion of molecules) – Eddy viscosity Mechanical turbulence Thermal turbulence Coriolis Effect – arises from rotating reference frame (important over long distances) Centripetal Force – for curved motion Gravity – only in vertical direction

3. Pressure Gradient Force

4. Friction Force Mechanical ViscosityThermal Viscosity Friction always opposes the motion Above 1 km the frictional forces are zero wind direction

5. Coriolis Effect

6. Hydrostatic Equilibrium

7. Geostrophic Wind (no friction)

8. Gradient Wind (no friction)

9. Surface Wind (friction) (vectors)

10. Friction Decreases with Height