THE HYDROSPHERE
Do you konw……..? Where can we find water in our planet? How is sea water different to water in rivers? What is the water cycle? Why is important not to waste water? Some easy ways to save water?
WHERE IS WATER ON THE EARTH?
WHERE IS THERE WATER ON EARTH? 97% of water on Earth is salt water. It is found in the oceans. 3% of water on Earth is fresh water. It is found in: Ice and snow from glaciars. Below the surface: groundwater. In the atmosphere. On the surface. In living beings.
PROPERTIES OF WATER The water molecule is made up of three atoms: H2O Has no colour, no taste and no smell. Is a poweful solvent. Absorbs heat: so, water moderates the Earth’s climate by absorbing heat in summer and emitting heat in winter.
SEA WATER Sea water is salty. It contains dissolved gasses: these gasses are dissolved in the water by two process: The movement of the waves. The aquatic beings.
The temperature varies with depth: It is highest at the surface. It is lower in the deepest zones.
MOVEMENTS PRODUCED IN THE OCEANS: Waves: occur on the surface, and they are caused by the wind. Waves mix water with the air above the surface, dissolving a lot of oxygen.
Currents: are masses of water which move like rivers through the sea Currents: are masses of water which move like rivers through the sea. They are produced by wind, and differences in salinity.
Tides: are the periodic rise and fall of the sea level Tides: are the periodic rise and fall of the sea level. They are caused by the gravitational attraction of the Moon and the Sun.
FRESH WATER Fresh water is found on the continents. It contains much less salt than sea water. It is found in different forms: Streams: are water courses fed by rain. Glaciers: are formed from the accumulation of snow on mountain tops. Rivers: are permanent water courses. Lakes: are masses of water contained on depressed areas. Groundwater: is water beneath the ground surface. Wetlands: are areas where the ground is inundated all year round.
THE WATER CYCLE
Is the movement of water around, over and through the Earth Is the movement of water around, over and through the Earth. It consist on these processes: Evaporation. Evapotranspiration. Condensation. Precipitation. Surface Runoff.
Evaporation: liquid water changes to gas Evaporation: liquid water changes to gas. Water passes from the hydrosphere to the atmosphere.
Evapotranspiration: water evaporates from the leaves of plants.
Condensation: Water vapour changes to liquid, forming clouds.
Precipitation: water in the clouds falls to the ground.
Surface Runoff: surface water moves across the land, forming rivers and streams.
Infiltration: surface water filters into the ground, using the pores in the rocks.