1. Chapter 9: The Hydrosphere

2. Liquid at ordinary Earth temperatures High heat capacity Expands when cools Capillarity Universal solvent Water is not distributed evenly around Earth Hydrologic cycle –Ceaseless interchange of moisture in both geographical location & physical state The Hydrologic Cycle

3. 99% stored in oceans, lakes, rivers, glacial ice, or rocks beneath the surface Remaining fraction involved in a continuous sequence of movement and change Movement is the hydrologic cycle Figure 9-1

5. The Hydrologic Cycle Figure 9-2 3 primary movement types –Surface to air Evaporation –Air to surface Precipitation –Movement beneath the surface Runoff Residence times –Minutes to millennia

6. The Hydrologic Cycle Figure 9-3 Precipitation & evaporation/ transpiration balance over time –Evaporation exceeds precipitation over ocean –Precipitation exceeds evaporation over land

7. The Oceans Majority of surface is ocean 4 principal parts –Pacific –Atlantic –Indian –Arctic –5 th ocean Southern Ocean Smaller bodies –Seas, gulfs, bays, etc. Figure 9-5

8. The Oceans Ocean water characteristics –Chemical composition Salinity –Sodium & chlorine –Temperature Decreases with increasing latitude –Density High temperature = low density High salinity = high density –Increasing acidity CO 2 absorbed by ocean water = carbonic acid Affects microscopic creatures’ shells Figure 9-6

9. Movement of Ocean Waters 3 primary groups: tides, currents, and waves Tides –Bulges in sea surface –Significant in shallow water areas for horizontal placement of water Causes of tides –Gravitational attraction of Moon (lunar tides) & Sun (solar tides) –More gravitational force on side of Earth facing Moon –More centripetal force on opposite side to keep Earth in orbit –2 bulges form on opposite sides of planet Figure 9-7a

10. Movement of Ocean Waters Causes of tides (cont.) –Two tidal cycles in 25 hours –Flood tide & high tide –Ebb tide & low tide Monthly tidal cycles –Tidal range—difference between high & low tides –Spring tides –Neap tides Tidal bore Global range of tides Figure 9-7b and c Figure 9-9

11. Movement of Ocean Waters Currents –Surface currents develop from surface wind patterns –Deep ocean circulations Result from differences in temperature & salinity in deep ocean water Thermohaline circulation –Global conveyer-belt circulation Figure 9-10

12. Movement of Ocean Waters Waves –Disturbances to the sea surface Changes shape of the ocean surface –Disturbances in Earth’s crust also trigger motion Tsunami –Little forward progress is observed –Wave breaking can result in shifting of water

13. Permanent Ice – The Cryosphere Cryosphere –2 nd largest water storage on Earth –2 groups Ice on land –Alpine glaciers –Continental ice sheets Ice in water –Ice pack –Ice shelf –Ice floe –Iceberg –About 10% of Earth’s surface is ice Figure 9-12

14. Permanent Ice – Glaciers Natural accumulation of land ice that flows downslope or out from center of accumulation Figures 19-5a & 19-17

15. Permanent Ice – Pack Ice Largest ice pack found in Arctic ocean Figure 9-13

16. 16 Permanent Ice – Ice Shelf Several large ice shelves attached to Antarctica –Larsen-B Ice Shelf –Broke off 2002 –Larsen-C & Wilkins Ice Shelves are currently disintegrating

17. 17 Permanent Ice – Ice Floe & Iceberg

18. Permanent Ice – Permafrost Permafrost –Permanently frozen ground Figures 9-15 & 9-16

19. Surface Waters 0.02% of water supply Lakes—bodies of water surrounded by land –Need: Natural basin Sufficient water supply –Most are short-lived Human alteration of lakes –Irrigation –Water diversion projects –Reservoirs Hydroelectric power Municipal water Agriculture Figures 9-17 & 9-19

20. Lakes are more common in areas that have been glaciated Surface Waters Figure 19-28

21. Surface Waters Swamps and Marshes –Flattish places periodically submerged, but shallow enough to permit plant growth –Swamps = trees –Marshes = grasses Figure 9-23

22. Surface Waters Streams –Allow for drainage of land surface water towards oceans –Drainage basins Figure 9-24

23. Underground Water Water beneath land surface worldwide –Underground water vs. Groundwater Precipitation or water basins provide water sources Quantity held depends on: –Porosity –Permeability

24. Underground Water Aquifers –Where groundwater is stored –Confined vs. unconfined Aquicludes –Impermeable rock layer that prevents water movement Figure 9-25

25. Underground Water Zone of aeration –Topmost layer –Mix of air & water in pore spaces –Water amount fluctuates rapidly Zone of saturation –ALL pore spaces filled with water –Groundwater –Top of zone = water table –Well water drawn faster than replenished creates a cone of depression Figure 9-26

26. Underground Water Zone of confined water –Water is trapped between 2 aquicludes –Pressure causes water to rise to piezometric surface –Artesian well vs. sub-artesian Waterless zone –Pressure too great to sustain water Figure 9-27

27. Underground Water Groundwater mining –Slow accumulation vs. rapid human use –Ogallala Aquifer Water table drops with increased use Numerous wells tapped Unsustainable situation Figure 9-30

28. Summary Most of the water on the planet exists in the oceans The hydrologic cycle describes the transition of water from land to sea to air Ocean water has numerous defining characteristics Ocean water movement is affected by gravitational pull from celestial objects (tides) Ocean water moves through currents based on salinity and temperature Winds and ocean surface disturbances result in waves on the ocean surface The cryosphere holds a large percentage of the Earth’s water content The ice in the cryosphere contains no salt Permafrost is permanently frozen landscape Surface water represents a very small fraction of the total Earth water content Surface water processes constitute an important part of the hydrologic cycle Lakes are bodies of water surrounded by land Swamps and marshes exist in areas that are shallow and can support plant life Rivers and streams help distribute water back to the oceans and replenish lakes Underground water exists due to water basin seeping or precipitation Human interactions in above ground and below ground water areas have drastically altered the hydrosphere