The Hydrosphere

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The Hydrosphere

• Water, water everywhere?

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The Hydrosphere

• Definition
• Earths outer layer of water, uniting water in
  all its state liquid, gas, solid.
• Of this, 2.5 is freshwater
• Of this, 79 is frozen

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Redividing the Hydrosphere

• We can separate the hydrosphere into 3 general
  categories
• Inland water
• The cryosphere
• Ocean water

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A) Inland Water
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Inland water

• Definition
• 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

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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

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

• Criteria to consider while deciding a watershed
• Topography
• Geology (permeable rocks or not)
• Climate
• Vegetation
• Agriculture

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B) The cryosphere
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The cryosphere

• Definition
• Consists of all frozen water on the Earths
  surface
• The cryosphere encompasses
• Ice floes
• Glaciers
• Permafrost
• Frozen lakes and rivers
• Snow (etc.)

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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?

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Permafrost

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

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C) The oceans
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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)

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1. Surface currents

• Surface currents
• Controlled mostly by wind
• Move horizontally, usually in the first 400 m
• Example the golf stream

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2. Subsurface currents (deep currents)

• Description of Subsurface currents
• Occur at a depth of more than 800 m
• Are caused due to the variation of density
  between water layers

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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

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Changes due to temperature

• Factors affecting the variation of temperatures
• Depth
• The deeper the colder
• The mixed layers 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

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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.

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3. Thermohaline circulation

• Huge conveyor belt effect connecting the
  surface and the subsurface circulations
• Responsible for the distribution of heat around
  the world