The “Spheres” of EarthFox Lake Access, Killarney Provincial Park (Photo credit: André Manbodh)

Late

Fossil evidence suggests that life has existed on Earth for at least 3.5 billion years. Earth is the only planet known to support life.

The “Spheres” of Earth

distance from the Sunsize of the Earth presence of water presence (and size) of the Moon

Why?

Fossil evidence suggests that life has existed on Earth for at least 3.5 billion years. Earth is the only planet known to support life.

file:///Library/Desktop%20Pictures/Nature/Earth%20Horizon.jpg

The “Spheres” of Earth1. The lithosphere is the relatively thin outer crust of the Earth.

made of various mineralsforms tectonic plates ranges from 50-150 km thick

http://www.arthursclipart.org/nature/nature/earth%20cross%20section.gif

radius of the Earth is 6378 km.

The “Spheres” of Earth2. The hydrosphere consists of all the water on, under and over the surface of the Earth.

liquid, ice and water vapourmoves through the water cycleoceans cover 71% of Earthless than 0.023% of Earth’s mass

http://img136.imageshack.us/img136/8057/waterairlp9.jpg

3. The atmosphere is the layer of gas that is held to the Earth due to gravity.

The “Spheres” of Earth

http://img136.imageshack.us/img136/8057/waterairlp9.jpg

78% N2, 21% O2, 1% Ar, CO2, O3 and other gases.

gets thinner with altitude

99% of it is below 30 km (alt.)

blocks U.V. radiation ( O3 )

moderates surface temperature ( mostly CO2 )

The biosphere includes the areas of the lithosphere, hydrosphere and atmosphere that support life.

The “Spheres” of Earth

http://img136.imageshack.us/img136/8057/waterairlp9.jpg

most life exists within a very thin layer of land, water and sky

living things compete for the limited resources in this layer

unsustainable use of resources by humans can have a serious impact on the biosphere

Vocabulary

atmosphere

lithosphere

hydrosphere

biosphere

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