Download Notes Earth - Westmount High School

Module 2
The Earth and
The Material World
Internal
Structure of
the Earth
Earth’s Internal Structure
Earth’s Internal Structure (pp. 294-295)
Layer Name
Main Characteristics
Crust
Layer is solid. Its thickness varies:
- 5-10 km beneath oceans (oceanic crust)
- 30-65 km beneath continents (continental crust)
Mantle
Core
Upper mantle (or
asthenosphere)
• Can be up to 670 km thick
• Layer is semi-fluid. Made of partially melted rock.
• Layer causes continental drift (plate tectonics).
Lower mantle
• Layer is solid – very hot with high pressure.
• Mainly made of silica, oxygen, iron and magnesium.
Outer core
• Layer is liquid.
• Layer gives rise to the Earth’s magnetic field.
• Approximately 2270 km thick.
Inner core
• Layer is solid – extremely hot with extremely high
pressure.
• Approximately 1216 km thick.
Like an egg…
Shell
(ALBUMEN)
Crust
Biosphere
Biosphere (pp. 295-296)
• The biosphere is all the regions in which life can
exist on Earth.
• Composed of three parts:
– Atmosphere (air)
– Hydrosphere (water)
– Lithosphere (land)
Atmosphere
Atmosphere
Composition
Atmosphere (pp. 296-300)
• Atmosphere is the envelope of gas that
surrounds the Earth.
• Composition:
– Nitrogen (78%)
– Oxygen (21%)
– Carbon dioxide, Ozone, Water Vapour, Other gases
(1%)
• Divided into 4 layers: Troposphere,
Stratosphere, Mesosphere, Thermosphere.
Ozone Layer
Layers of the Atmosphere:
Troposphere
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•
•
•
Up to 17 km thick near equator.
7-8 km thick near north and south poles.
Contains 80% of the atmosphere.
Contains almost all the water vapour in
the atmosphere (clouds, rain, etc).
• Drops approximately 6°C each kilometre.
Stratosphere
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•
•
•
•
Approximately 40 km thick.
Above troposphere.
Contains ozone layer.
Absorbs ultraviolet rays.
The farther from Earth, the higher the
temperature.
• Large airplanes fly here.
Mesosphere
•
•
•
•
•
Approximately 40 km thick.
Third layer.
Meteoroids catch fire and break up here.
Air is very thin (molecules are scarce).
Temperatures between -120°C and 27°C.
Thermosphere
•
•
•
•
•
Over 90 km thick.
Fourth and last layer.
Contains polar auroras.
Very hot (over 1000°C).
Contains ionosphere (useful for
communication systems).
• Burns up most meteoroids (shooting
stars).
The Ozone Layer
• The protective ozone layer has been shrinking in
volume because CFC molecules and aerosol
products are destroying it.
• CFC molecules are chlorofluorocarbon molecules
found in refrigerators and air conditioners.
• When the ozone layer shrinks, it cannot protect
us as well from solar UV rays.
• UV rays are trapped inside our atmosphere
because of the greenhouse effect.
Hydrosphere
Hydrosphere
Hydrosphere (pp. 302-303)
• The hydrosphere is formed by all bodies of
water on the Earth’s surface.
• Some parts are: oceans, rivers, streams, lakes.
• Covers approximately 75% of the Earth’s
surface.
• Water is essential for survival.
Distribution of Water on Earth
• Water is either fresh or salty.
– Fresh water can be found in lakes, ponds, and
streams.
– Seas and oceans have salty water.
• Humans need fresh water to survive.
Distribution of Water on Earth
So, what’s the big deal?
Another look
Water Cycle
Water on Earth is constantly being
recycled.
The Water Cycle
The amount of water on Earth is constant.
Water follows a cycle: it travels constantly
between oceans, the atmosphere and solid
ground.
– A cycle has no beginning and no end
There are 4 main steps in the water cycle:
1. Evaporation
• Evaporation: Liquid water becomes water
vapor.
• Evapotranspiration: Living things produce
water vapor through respiration and
transpiration.
2. Condensation:
Water vapor is cooled down and becomes
liquid water.
3. Precipitation:
Small water droplets
in clouds gather and
become rain drops
which gravity pulls
to the ground.
4. Return to ocean
• Runoff: Water on mountains and on hills
reaches waterways because of height
differences.
• Infiltration: Water can seep to
underground lakes and make its way
back to the ocean.
Lithosphere
The Lithosphere (p. 306 top only)
•
•
•
•
Made of crust and part of upper mantle.
70 km thick below oceans.
150 km thick below continents.
Essential for life:
– Provides minerals to plant roots.
– Offers habitat for animals.
– Contains oil and natural gas.
– Foundation for buildings.
• Constantly changing due to tectonic plate
movement.