LIGHT & HEAT

1. LIGHT & HEAT IN INLAND WATERS

2. Light spectrum at the top and bottom of the atmosphere

3. Measurable Properties of Light • Intensity • Quality Both are dependent on absorption and reflection by the atmosphere

4. Fates of light in water

5. Shading of low order streams

6. Confluence of Kotorosl and Volga Rivers

7. Walker Lake

8. Extinction Coefficient ν (nu) = extinction coefficient of light through water. Examples: • Crystal Lake v = 0.19 • Turbid Pond v = 1 – 10 • Muddy Stock Tank v = >>10-150 • Depends on: • Light absorption by water • Light scattered and absorbed by particles • Light absorbed by dissolved substances • v ~ 1/secci depth

9. Secci Disk

10. Typical Secci Depths • Crater Lake 40m • Castle Lake 33m • Lake Texoma 0.75m • Susquehanna River • West Shore >1.2m • West Center 0.32m • East Center 0.23m • East Shore 0.18m • Secci Depth measured with Secci Disk in lakes and with a Secci Tube in running water. • Also measured with Turbidimeter (JTU)

11. Susquehanna River at Byer’s Island

12. Lakes Erie and St. Claire following major runoff event

13. Heat Budget for Lakes Sources • Solar radiation • Sensible heat conduction • Stream Input • Sediment absorption of sunlight • Geothermal • Biogenic Sinks • Evaporation • Sensible heat conduction • Back radiation from lake surface • Stream inputs (snow melt) • Surface outflow

14. Annual Lake Heat Budget where S = storage rate of heat in the lake Rn = net radiation E = evaporation H = sensible heat transfer, conduction Q = advective heat transfers due to water inflows and outflows S = Rn – E – H – Q

16. Lake Tahoe, CA-NV

17. Lake Mendota, WI

18. Density and temperature

19. Stratification

20. Castle Lake Stratification

22. Lake Classification Based on Thermal Stratification Patterns • Holomixis • monomictic – mixes once per year • warm monomictic – never below 4°C • cold monomictic – never above 4°C • ex: Lake Tahoe • large volume and large depth • no winter ice cover

23. Fall turnover occurs when the center of gravity (M) approaches the center of the volume (X).

25. Martin Lake

27. dimictic – mixes twice per year • ex: Castle Lake and Lake Mendota • small temperate lake • freezes over during winter • amictic – does not mix, permanently ice-covered • ex: Lake Vanda, Antarctic • high latitude lake

28. Lake Vanda, Antarctica

30. Meromixis

31. Lake Nyos

32. Lakes Nyos(A&C) and Monoun(B&D)

33. Polymixis in Clear Lake(Rueda et al. 2003)