1. THE HYDROSPHERE

2. THE HYDROSPHERE
Three quarters of the surface of the Earth are covered by water.
Hydrosphere refers to all the water on the planet (solid, liquid and gas).

3. LIQUID Seawater (most liquid water) found in: Oceans Seas
Inland water (small percentage)
Surface water (lakes and rivers)
Ground water (underground like aquifers)
Liquid water exists between 0ºC and 100ºC.
Clasification of the water by the SALT LEVEL:
Fresh water: low content
Brackish water: moderate sal content
Salt water: high salt content

4. SOLID
Solid water exists as snow and ice in the polar ice caps and glaciers. Liquid water freezes below 0ºC and transforms into solid.

5. GAS
Water is considered gas in the form of water vapour. Water vapour exists as evaporation from surface water. It can also come from inside the earth in areas of volcanic activity (geysers)

6. THE DISTRIBUTION OF WATER IN EARTH
Water in seas and oceans.
Inland water:
Surface water.
Ground water.
Glaciers.

7. WATER IN SEAS AND OCEANS
COMPOSITION
Sea water is a mixture of mineral salts (NaCl).
It also contains magnesium salts.
Salt in seawater affects density:
“Water with a higher salt content has a greater density”

8. Seawater temperature depends on depth:
Temperatures are lower in deeper bodies of water.
Temperatures are warmer in shallower areas.

9. MOVEMENT
Oceans and seas move and change all the time in variety of ways:
Waves:
They occur on the surface of the water.
They are caused by the wind.
Tide:
It´s a regular movement in which the sea level rises and falls.
It is caused by the gravitational force of
the Sun and the Moon.

10. Ocean currents: They are horizontal movements of water in seas and oceans. They are important because they redistribute heat and salt to different areas of the Earth.

11. The water cycle Earth water distribution is generally constant.
The water cycle refers to the continual process of exchange between surface water, groundwater and the atmosphere.

12. Evaporation
The Sun heats up liquid water and it evaporates turning into water vapour which is part of the atmosphere. This process is called EVAPORATION.

13. Transpiration
The process of evaporation from plants is called transpiration. It’s caused by heat from the Sun.

14. Condensation
The water vapour produced by evaporation and transpiration rises, cools down and then when a large amount of water vapour condenses it turn into clouds.

15. Precipitation
when water in clouds gets too heavy it returns to the Earth’s surface as rain, snow or hail.

16. Underground/Surface runnof
When rain falls on the surface of the Earth, some of the water penetrates the surface and becomes underground runnoff.
The surface runnof is the other precipitation that flows across the land. This water forms the rivers and they return the water to the seas and oceans.

18. The properties of water
Pure water has no taste, colour or smell
CHEMICAL STRUCTURE:
Water molecules (H2O)are composed by two hydrogen(H) atoms and one oxygen(O) atom. H O

19. The properties of water. Chemical structure.
Water molecules are held by hydrogen bonds.(negative oxygen end of one water molecule is attracted by positive hydrogen end of another water molecule)

20. The properties of water. Universal solvent:
Water is capable of dissolving many solids, gases and other liquids.

21. The properties of water. Boiling and melting points:
Water remains in liquid state between 0ºC and 100ºC because the strong bonds of the molecules.
Most water on Earth is liquid which makes it possible to life to exist.

22. Temperature regulation:
A lot of heat is needed to raise the temperature of water and it also take a long time to cool down.
This high specific heat capacity facilitates life on Earth by keeping temperatures constant.

23. Density variation: The density of water decreases under 4ºC.
Ice floats on the surface of water.
The insulating top layer allows living things to survive below the surface.
The density of water decreases under 4ºC.
Ice floats on the surface of water.
The insulating top layer allows living things to survive below the surface.

24. Why water is important in human body and living things?
Living things need water to make the processes like photosyntesis or nutrition. Water is the medium for the chemical reactions of life.
Water is important because in organisms up to 90% of their body is water. In humans 63% aprox. is water.
It´s very important to drink water, we should drink 1.5 L a day.

25. Why water is important in the climate and the landscape?
Water is the most important external geologic agent that modifies the Earth´s surface
The average temperature determines the Earth´s climate zones
Occean currents help to transport heat between regions and regulate the temperature of the planet