Zoology 315: Limnology Water, Light, & Stratification Abby Popp June 21st, 2006 Properties of water: 1. Molecular shape of water Polarity— Hydrogen Bonds— 2. Viscosity & Surface Tension Results from: Importance: 3. Water as Solvent Why is water a good solvent? Examples 4. Density Buoyancy in water:Temperature & density: Salinity & density: 5. Specific Heat Definition: Heat of melting/fusion: Heat of vaporization: Importance: 6. Absorption of solar radiation The importance of light to lakes: Light 1. Properties of light2. Factors determining light penetration (7) 3. Fate of light A. Reflection B. Absorption C. Scattering 4. Penetration of light Light Extinction Extinction coefficient & equation I0 = Iz = z = kd = Variability of light penetration:Lake zones: Photic zone: Aphotic zone: Compensation depth: 5. Differential penetration of light 6. Implications Heat & Stratification 1. Lake Stratification Epilimnion Metalimnion Hypolimnion Thermocline2. Density and resistance to mixing Warm vs. cool lakes Relative Thermal Resistance (RTR) 3. Lake classification A. Dimictic Lakes B. Cold monomictic Lakes C. Warm monomictic Lakes D. Meromictic Lakes E. Cold & Warm Polymictic Lakes F. Amictic Lakes4. Case study: Lake Nyos,