UNIT 6 THE HYDROSPHERE THE HYDROSPHERE The hydrosphere

UNIT 6: THE HYDROSPHERE

THE HYDROSPHERE The hydrosphere is all the water on the surface of the Earth. Water is made up of two atoms of hydrogen and one of oxygen. (H 2 O) More than 70% of the planet is covered by water. 97% is salt water and 3% is fresh water. Water is distrubuted in: Oceans Continental waters: Lakes, rivers, groundwater. Glaciers and ice caps Clouds

THE WATER CYCLE There are three stages: Water becomes part of the atmosphere: Evaporation: The sun heats and evaporates the water in rivers, lakes and oceans. Transpiration: Animals and plants release water vapour into the atmosphere. Water returns to the surface of the Earth: Condensation: Water vapour cools down and condenses, forming clouds. Precipitation: Water falls to the surface of the Earth. Water circulates throughout the surface of the Earth: Surface run-off: Water moves along the slopes of mountains. Infiltration: The rain water filters into the ground, forming aquiferous.

ACTIVITIES 1. Answer the questions: a)How much of earth’s surface is covered by water? b)What is the name of the water in a solid form? c)What causes evaporation? 2. Choose the correct answer: a) Evaporation/Transpiration occurs when plants lose water from their leaves. b) Salt water/Fresh water is more abundant on Earth. c)Rain and hail are different types of precipitation/condensation.

3. Tick (√) the correct state of water: Solid Liquid Gas A river An iceberg A glacier A cloud A lake 4. In what state do we find the largest quantity of fresh water on Earth? 5. List the different types of continental waters.

6. Complete using the water cycle: a) The sun heats the water: ____ b) Water falls to the surface of the Earth: _____ c) Water moves along the slopes of mountains: ____ d) The rain water filters into the ground, forming aquiferous: ____ e) Water vapour cools down and condenses: ____ f) Animals and plants release water vapour: ______

WATER IS A UNIQUE COMPOUND Special properties of water: Water is a good solvent. Water absorbs and accumulates heat. Anomalous dilation: ice density is lower than water density. Physical properties of water Fusion temperature 0ºC Boiling point 100ºC

THE IMPACT ON WATER Pollution of water: Sewage Plastics, batteries, oil, etc. Other impacts: Overexploitation of groundwaters. The building of dams for storing water.

SAVE WATER! Have a shower instead of a bath. Turn off the tap when brushing our teeth. Turn off the tap when washing our hands. Only use the dishwasher or washing machine when they are full. Water plants at night so that water is not evaporated. Repair water leaks.

ACTIVITIES 7. What are the main properties of water? 8. What is the percentage of fresh water on Earth? 9. True or false? a)Water can’t dissolve substances. b)Water freezes at -4ºC c)Most of the water on Earth is underground. 10. What impacts affect water?