Hydrosphere The hydrosphere includes all water on Earth.

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2 Hydrosphere The hydrosphere includes all water on Earth. The abundance of water on Earth is a unique feature that clearly distinguishes our "Blue Planet" from others in the solar system. Not a drop of liquid water has been found anywhere else in the solar system. the "Goldilocks" principle permits water to exist mainly as a liquid.

3 Distribution of Water on Earth

4 Hydrosphere The range of surface temperatures and pressures of our planet permit water to exist in all three states: solid (ice), liquid (water), and gas (water vapour). Water is the universal solvent and the basis of all life on our Planet. It is an essential life-sustaining resource.

5 Ocean basins Cover 70% of the surface Lower than continents Oceanic crust Collect sediments

6 Echo Sounders for Measuring Ocean Depths and Floor Profiles

7 Major Topographic Divisions and Profile of the North Atlantic Ocean Basin

8 The World s Ocean Floors

9 Typical Elevation Profile of Oceanic Margins

Oceans Oceans are responsible for keeping the planet from burning up or freezing The large mass of liquid serves as a buffer for the sun s heat and it keeps earth

10 Oceans Oceans are responsible for keeping the planet from burning up or freezing The large mass of liquid serves as a buffer for the sun s heat and it keeps earth in a state of homeostasis by not allowing any drastic changes in temperature Why would it be important to keep the earth s temperature at a relatively constant state?

11 Water s heat capacity It takes 1 calorie of heat to raise the temperature of 1 cubic centimeter of water by 1 degree celsius. Most of the water is contained in the oceans and the high heat capacity of this large volume of water (1.35 million cubic kilometres) buffers the Earth surface from large temperature changes

Ocean Currents pull CO 2 down to the deeper portions of the ocean carry warm waters from equatorial regions to those near the poles These currents are sent in

12 Ocean Currents pull CO 2 down to the deeper portions of the ocean carry warm waters from equatorial regions to those near the poles These currents are sent in motion by prevailing winds Coriolis force, which is the force created by the rotation of the earth influences direction account for 1/4 of the heat transport on the earth

13 Deep ocean currents The Great Ocean Conveyor - thermohaline circulation Differences in density temperature & salinity More heat than 1 million nuclear power plants Strongly influences climate

14 When the conveyor breaks down Last time it broke down ice age Could it happen again, or could it melt the ice caps? The Pentagon is concerned.

15 ICE AGES The most recent ice age ended about 12,000 years ago, which was prior to the advent of civilized human history. It is still unknown as to what causes the advent of ice ages, but it is thought that the last one occurred when Panama closed off

16 Ice Age North Polar Coverage

GLOBAL WARMING At the current time, we are experiencing

extent this is part of a natural cycle as distinct from

ice caps, which would raise the water level of the

17 GLOBAL WARMING At the current time, we are experiencing a slow global warming, but it is not known to what extent this is part of a natural cycle as distinct from human-induced Could also result in melting of the polar ice caps, which would raise the water level of the oceans and cause flooding of coastal areas of the continents.

18 Sea Level Changes due to Ice Ages and Ice Cap Melting

The Ocean and the Atmosphere The oceans are the earth s main reservoirs of readily available carbon dioxide (CO 2 ). Why do you think that this would be important to the earth s atmosphere?

19 The Ocean and the Atmosphere The oceans are the earth s main reservoirs of readily available carbon dioxide (CO 2 ). Why do you think that this would be important to the earth s atmosphere? Carbon dioxide is an important greenhouse gas CO 2 is important in the process of photosynthesis in plants It is the deep circulation that allows the creates the cycle that allows the entrapment of CO 2 at the deeper, colder regions of the ocean

20 Oceans and Oxygen Half of Earth s atmospheric oxygen comes from phytoplankton

21 Tides rise and fall of sea levels caused by the combined effects of the gravitational forces Most places in the ocean usually experience two high tides and two low tides each day

22 Tides and gravity Caused by the Moon Moon s gravity pulls the water towards it Side opposite the Moon, has a tidal bulge rebound

23 Spring and Neap tides Spring tide Moon and Sun gravity combine to produce a higher than normal tides Neap tide moon and Sun at 90º to each other. Results in lower than normal tides

24 Salt water Most water on Earth is salty Makes it more conductive Electricity Heat Mostly NaCl dissolved

25 Salinity A measure of saltiness

26 "When the well's dry, we know the worth of water." How much is usable by Humans? although our planet is nearly ¾ covered by water, there is only a small percentage of it usable by humans It is the saline (salt) content in the water that makes it unusable to humans Humans have found ways to filter the water and make it usable, but these processes are still slow and costly

27 Water resources Adult humans need 2.7 to 3.7 liters of water every day There are 7 billion people on Earth That s 22.4 billion liters of water every day, just for drinking water for humans 69% of worldwide water use is for irrigation 15-35% of irrigation withdrawals unsustainable 22% of worldwide water use is industrial

28 Freshwater Low concentrations of salts Only 2.75% of the hydrosphere Most of that is frozen Fresh and unpolluted water accounts for 0.003% of total water available globally

29 Groundwater Located in spaces between particles of soil Deposits of groundwater are called aquifers

30 Watershed A watershed is a geographic area in which all water running off the land drains to a specific creek, river or stream

31 Watershed vs. Basin A basin is a large-scale watershed, such as the St. Lawrence River basin

32 Cryosphere Water in the solid form Sea ice, lake and river ice Permafrost Snow cover Glaciers Ice caps and ice sheets 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet if melted, would cause sea levels to rise by 61.1 meters

33 Permafrost in Land Areas Regions in which soil water is permanently frozen constitute what is known as permafrost. Land areas in polar regions, such as Antarctica and Greenland, and the north slopes of Alaska and Siberia, have zones below their surfaces in which ground water remains frozen yearround.

34 Summary The hydrosphere includes all water on Earth 97.2% of the hydrosphere is in the oceans Earth s climate allows for solid, liquid, and vapor water. Ocean basins cover 70% of the surface The oceans get deeper at the continental shelves The high heat capacity of of water buffers the Earth surface from large temperature changes

35 Summary Ocean currents pull CO 2 down to the deeper parts of the oceans, and account for ¼ of the heat transport on Earth Differences in density (temperature and salinity) drive the Great Ocean Conveyor Last time the conveyor broke down there was an ice age (Panama closed off) Or the ice caps could melt, raising ocean levels

36 Summary Oceans are the main reservoir of CO 2, easily trapped in cold, deep water Half of Earth s oxygen comes from phytoplankton Tides are the rise and fall of sea levels caused by gravity Moon pulls the water up, opposite side has rebound bulge Sun and Moon s gravity can combine to make spring and neap tides

37 Summary Most water on Earth is salty, mostly NaCl Salinity measures saltiness fresh, brackish, saline, and brine water Only 2.75% of the hydrosphere is freshwater Deposits of groundwater are called aquifers

38 Summary A watershed is a geographic area in which all water running off the land drains to a specific creek, river or stream A basin is a large-scale watershed The cryosphere is the term which collectively describes the portions of the Earth s surface where water is in solid form, Permanently frozen ground is permafrost

39 Questions How is the hydrosphere connected to the other spheres we ve seen in class? (Think in terms of climate change) Is fresh water a renewable resource? Explain your answer

HYDROSPHERE NOTES. Water cycle: The continuous movement of water into the air, onto land, and then back to water sources.

HYDROSPHERE NOTES. Water cycle: The continuous movement of water into the air, onto land, and then back to water sources. Hon Environmental Science HYDROSPHERE NOTES The Hydrosphere and the Water Cycle: Water cycle: The continuous movement of water into the air, onto land, and then back to water sources. Evaporation: the