1. Topic 8: Water and Climate

2. The Water Cycle Climate – the conditions of the atmosphere over long periods of time Water cycle – the movement and phase changes at and near Earth’s surface  Fueled by insolation and gravity  Also known as the hydrologic cycle.

3. The Water Cycle 97% of Earth’s water is held in oceans About 80% of Earth’s fresh water is in glaciers Graph of pg 160 in book

4. The Water Cycle Four places that precipitation goes if it lands on land:  Water retention: water is held on land as ice or snow or on leaves of trees and plants  Infiltration: soaks into ground  Runoff: flows over Earth’s surface  Evapotranspiration: water evaporates, sublimates or transpirates back into atmosphere  Most precipitation returns to atmosphere

5. Condensation and sublimation (cloud formation) Precipitation Sublimation Transpiration Runoff Zone of aeration Water table Zone of saturation Bedrock = impermeable Evaporation Infiltration

6. Factors Affecting Infiltration 7 Factors affecting infiltration:  Slope of the land  Degree of saturation  Porosity  Permeability  Capillarity  Vegetation  Land use

7. Slope What effect does slope of the land have on infiltration  Steeper slope = less infiltration slope Infiltration

8. Degree of Saturation What effect does degree of saturation have on infiltration?  The more saturated the ground = less infiltration saturation Infiltration

9. Vocabulary Zone of aeration – pores of soil partly filled with air and partly filled with water (capillary water) Zone of saturation – pores of soil are filled with water Water table – interface between zone of aeration and zone of saturation Groundwater – subsurface water below the water table

10. Porosity Porosity – percent of open pore space in a material compared to its total volume What effect does porosity have on infiltration?  The greater the porosity the greater the infiltration

11. Porosity Effect of the particle characteristics on porosity:  Shape : round particles = high porosity angular particles = low porosity  Packing : loose = high porosity packed = low porosity  Sorting : sorted = high porosity unsorted = low porosity  Size : DOES NOT AFFECT POROSITY

12. Permeability Permeability – how easily water passes through a material  Permeability rate – how fast water passes through a material Two factors that affect permeability  How well connected pores are  Size of pores

13. Permeability What effect does permeability have on infiltration?  The more permeable the ground is the more water will infiltrate  The more permeable the faster water will infiltrate (less time)

14. Capillarity Capillarity – the “stickiness” of water to ground particles Why is capillary action important?  It brings water to the roots of plants What is the effect of particle size on capillarity?  Smaller particles = greater capillarity = more capillary water

15. Vegitation What is the effect of vegetation on infiltration?  More vegetation = more infiltration less runoff  Less vegetation = less infiltration more runoff

16. Land Use What is the effect of land use on infiltration?  Urbanization decreases infiltration  More paved surfaces (roads, parking lots, buildings)  More runoff

17. Runoff What are the situations that can lead to runoff?  Rate of precipitation is greater than rate of infiltration (permeability rate)  Pore space if saturated  Slope is too steep to allow infiltration  Water on surface has not evaporated

18. Stream Discharge Stream discharge – the amount of water flowing past a spot in a certain amount of time  m 3 /s or L/s

19. Flooding Flooding is the result of:  When a stream overflows its channel  When precipitation is greater than infiltration  A hurricane storm surge  Rising sea  Sinking land

20. Climate

21. Climate – the conditions of the atmosphere over long periods of time

22. Temperature and Moisture Two important factors concerning temperature and climate:  Average temperature throughout the year  Range of monthly average temperatures

23. Evapotranspiration Potential evapotranspiration – amount of water that would evapotranspirate if water was available  Determined by temperature (available energy)

24. Arid Climates An arid (dry)climate occurs when total precipitation is less than potential evapotranspiration  Atmosphere can evaporate more water than is falling

25. Humid Climates A humid (moist) climate occurs when precipitation is more than potential evapotransipiration  Atmosphere is trying to evaporate less than is falling

26. Factors affecting Climate 8 Factors affecting climate  Latitude  Planetary wind and pressure belts  Oceans and large bodies of water  Mountains  Elevation  Cloud cover  Vegetation

27. Latitude How are latitude and temperature related?  Higher latitude = lower temperatures (yearly)

28. Latitude and Moisture What causes moisture conditions to vary with latitude?  Planetary wind and pressure belts  Lows = humid climates  Highs = deserts, arid climates

29. Latitude and Moisture At what latitudes are there moist conditions? Why?  0 o, 30 – 60 o (mid latitudes)  Low pressure – rising air cools = precipitation

30. Latitude and Moisture At what latitudes are there arid conditions? Why?  Poles, 30 o N, 30 o S  High pressure – sinking air warms(compression) = lower RH