1. Water, water everywhere?
The Hydrosphere
Water, water everywhere?

2. The Hydrosphere Definition:
Earth’s outer layer of water, uniting water in all its state: liquid, gas, solid.
Of this, 2.5% is freshwater
Of this, 79% is frozen

3. Redividing the Hydrosphere
We can “separate” the hydrosphere into 3 general categories:
Inland water
The cryosphere
Ocean water

4. A) Inland Water

5. Inland water Definition How do we manage and study inland water?
Fresh water bodies found on continents. This unites rivers, lakes and groundwater
How do we manage and study inland water?
We divide the continent up into catchment areas

6. Catchment areas Definition:
A catchment area is the territory surrounding a waterway.
All the water that falls in this territory will drain into the waterway

7. The red area shows the catchment area for the small river.

8. Catchment area Criteria to consider while deciding a watershed:
Topography
Geology (permeable rocks or not)
Climate
Vegetation
Agriculture

9. B) The cryosphere

10. The cryosphere Definition:
Consists of all frozen water on the Earth’s surface
The cryosphere encompasses:
Ice floes
Glaciers
Permafrost
Frozen lakes and rivers
Snow (etc.)

11. Ice Floes vs. Glaciers
Ice floes are composed of ice floating on the oceans near the North and South poles.
A glacier is a mass of ice on land formed by compressed snow
What would be the effects if global warming melts these parts of the cryosphere?

12. Permafrost
Permafrost is ground whose temperature has been 0C or lower for at least two years.
This covers almost 50% of land in Canada.

13. C) The oceans

14. The Oceans Large masses of salt water
The oceans are moved all over the world by currents.
There are two types of currents
Surface currents
Subsurface currents (Deep currents)

15. 1. Surface currents Surface currents Controlled mostly by wind
Move horizontally, usually in the first 400 m
Example: the golf stream

16. 2. Subsurface currents (deep currents)
Occur at a depth of more than 800 m
Are caused due to the variation of density between water layers

17. Factors affecting subsurface circulation
Density variation:
Changes due to temperature
The colder the water, the denser it is
Changes due to salinity
The higher the salinity, the denser the water is

18. Changes due to temperature
Factors affecting the variation of temperatures:
Depth
The deeper the colder
The mixed layer’s temperature relatively stable
Seasons
In winter, the water will loose its stored energy
Latitude
Increase in latitude, decrease in temperature
At the equator the average surface temperature 25C-28C
At the temperate zones the average temperature 12C-17C

19. Changes due to salinity variation
Where does salt come from?
Salt comes from the erosion of rocks and the dissolution of salts. As salt does not evaporate, rivers and groundwater also bring salt to the ocean.
The higher the salinity, the denser the water will be.

20. 3. Thermohaline circulation
Huge “conveyor belt” effect connecting the surface and the subsurface circulations
Responsible for the distribution of heat around the world