Earth

The Earth

Earth

• • • • Roughly 4.5 billion years old Third planet orbiting around the sun Only planet in our solar system to have surface liquid water Home to the only known life in the universe

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Information on the Earth

Earth is the only planet whose English name does not derive from Greek/Roman mythology.

• It was not until the time of Copernicus the Earth is just another planet.

(the sixteenth century) that it was understood that • The Earth is divided into several layers which have distinct chemical and seismic

• • The Earth's atmosphere is 77% nitrogen, 21% oxygen, with traces of argon, carbon dioxide and water Earth has only one natural satellite, the Moon

Rotation of the Earth

• The cycle of day and night is produced by the rotation of the Earth on its axis

• • • The Earth turns on a tilted axis This rotation causes the cycle of day and night The cycle of the seasons is caused by the Earth’s revolution around the Sun and by the tilting of the Earth’s axis

The Northern and Southern Hemispheres

• In the summer the Northern hemisphere is tilted toward the Sun (and so receives the Sun’s rays more directly than the Southern hemisphere)

What are polar auroras?

• The polar auroras are caused by the solar wind. The particles are diverted toward the poles

Atmosphere

• • • • The gases that envelope and surround the Earth make up our atmosphere Protects us from UV rays Balances the global temperature on the Earth Made up of various gases (Nitrogen, oxygen, water vapour, Carbon dioxide, Ozone, etc...)

Layers of the atmosphere

Troposphere : contains 80% of all air Stratosphere: absorbs UV rays Mesosphere: Protects Earth from meteorites Thermosphere: Most meteorites burn up here.

Ozone

Protects us from UV rays Destroyed by CFCs (chloroflurocarbons) and aerosol products.

Hydrosphere

• The hydrosphere is the liquid water component of the Earth. It includes the oceans, seas, lakes, ponds, rivers and streams. • The hydrosphere covers about 70% of the surface of the Earth and is the home for many plants and animals

Hydrosphere

Fresh Water

Fresh Water

• Lakes, ponds, rivers, and streams are freshwater habitats. So too are swamps, bogs, and marshes.

• It amounts to precious little water, less than half a percent of the world's water supply.

• Yet it is essential to a wide variety of life on earth.

• The distribution of fresh water in uneven globally. Four countries hold nearly 50% of all the fresh water on Earth.

Salt water

• The water of the seas and oceans is salty because of the vast quantity of mineral salts dissolved in it.