Hydrosphere p 298 301 Hydrosphere DEFINITION Formed by

Hydrosphere p. 298 -301

Hydrosphere Ø DEFINITION: Formed by all bodies of water on the Earth’s surface Ø Includes oceans, rivers, streams, lakes and other waterways

Hydrosphere Ø Covers 75% of Earth’s surface Ø Without water there would be no life Ø Water can either be fresh or salty

Why are the seas and Oceans salty? Ø Seas and Oceans are salty because there a great quantity of mineral salts dissolved in it Ø Mineral salts come from rocks Ø When it rains, some minerals (which form the rocks) dissolve Ø Minerals run into the ocean where they accumulate

Are some Seas saltier than others? Ø The amount of salt in seas vary depending on the region in the world The Dead Sea – Saltwater Lake in the Middle East with salinity of 27%

Are some Seas saltier than others? Red Sea (Between India and Asia) 4. 1% salinity Great Salt Lake, Utah (USA) 5 to 27% salinity Most other seas are between 1 and 3 % salinity.

Which type of water can humans drink? Ø Humans can only drink fresh water because they can’t absorb the large quantity of mineral salts contained in salt water Ø When water is safe to drink it is called potable. Ø Potable water = drinkable water

Potable Water Ø To be potable water it must have the following characteristics: Ø Perfectly transparent Ø No suspended particles Ø No unpleasant odour Ø Contains little dissolved minerals Ø Contains dissolved oxygen Ø No micro-organisms that cause disease

Potable Water Ø 5. 6 billion people in the world Ø 1. 1 billion people in the world without access to adequate water and sanitation Ø In the news. . . Ø Do you have running water? Because I don’t and I live in Canada. Ø http: //www. youtube. com/watch? v=6_gq 9 J e 58 o. U Ø Water is whose responsibility?

But how much water is available for humans to drink? Works out to be about 0. 02% available fresh water

The Water Cycle Ø Ø Ø a) Evaporation - water from lakes, rivers and oceans changes to water vapour by the action of the sun. b) Transpiration - water vapour is released from plants by the action of the sun. c) Condensation - water vapour changes to droplets of liquid as it cools, leading to the formation of clouds. d) Precipitation - water from clouds is released back into lakes, rivers and oceans, as rain, snow or hail, or onto land where it seeps through the soil and travels as ground water back to the ocean. e) Melting - ice and snow change to liquid water by the addition of heat, and flow into lakes, rivers and oceans.

The Water Cycle

People upset the natural water cycle That is because we: Ø Create pollution Ø Remove the natural vegetation such as plants and trees Ø Pave over the natural environment and build houses etc. Ø Put in irrigation systems, build dams, change natural drainage systems, build wells