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Lesson #8 Earth’s Systems
Earth & Space Science
Lesson #8 Earth’s Systems
• Planet Earth is made
up of different
spheres:
– Lithosphere (solid part
of Earth; includes the
crust & mantle)
– Atmosphere (gaseous
part of Earth)
Hydrosphere (water
part of Earth)
– Biosphere (living
things on Earth)
(Image from http://krygier.owu.edu/krygier_html/geog_111/geog_111_lo/geog_111_lo16_gr/spheres.jpg)
Lesson #8 Earth’s Systems
Many processes occur in patterns
within the Earth's systems.
• Earth’s spheres (hydrosphere, lithosphere,
atmosphere and biosphere) are
interconnected
– Many substances (e.g., water, carbon, nitrogen)
cycle through Earth’s spheres. These cycles are
called biogeochemical cycles.
Lesson #8 Earth’s Systems
• The Water Cycle
(moves through the atmosphere,
biosphere, hydrosphere & lithosphere)
– In the Water Cycle, water
passes from vapor in the
atmosphere as rain onto the
land or body of water
– The water then transfers from
the lithosphere back into the
atmosphere through
evaporation (liquid water changes to
water vapor) & transpiration (liquid
water from plants changes to water vapor).
– That water then condenses
(water vapor changes to liquid water) in
the colder atmosphere and it
starts to rain, moving water
from the atmosphere to the
hydrosphere continuing the
cycle again.
(Images from http://ga.water.usgs.gov/edu/graphics/watercyclesummary.jpg and http://dnr.wi.gov/org/caer/ce/eek/earth/groundwater/watercycle.htm)
Lesson #8 Earth’s Systems
• The Nitrogen Cycle
(moves through the atmosphere,
biosphere & lithosphere)
– Nitrogen makes up 78% of
Earth’s atmosphere.
– Most nitrogen is in gaseous form,
which makes it not usable by life
on Earth.
– Microbes (microscopic
organisms) in the soil and in roots
of some plants convert or “fix”
nitrogen into a form that plants
can use (nitrogen fixation)
– Humans and animals get the
nitrogen compounds by eating
plants or by eating other animals
that have eaten the plants.
– Microbes return the nitrogen from
decaying matter and waste to the
gaseous form and the cycle
continues
(Image from http://www.kidsgeo.com/geography-for-kids/0161-the-nitrogen-cycle.php and http://www.h2ou.com/h2nitrogencycle.htm)
Lesson #8 Earth’s Systems
• The Oxygen Cycle
(moves through the atmosphere,
biosphere, hydrosphere &
lithosphere)
– Oxygen can be dissolved in
the air or in water.
– Plants and animals breathe
oxygen and return it to the
air and water as carbon
dioxide.
– Through photosynthesis,
plants convert carbon
dioxide and water into
carbohydrates, and release
oxygen.
– Algae in the oceans and
other water bodies replace
about 90% of all oxygen
used on our planet.
(Images from http://www.copperwiki.org/index.php?title=File:Oxygen_Cycle.jpg and
http://www.exploringnature.org/db/detail.php?dbID=27&detID=1186)
Lesson #8 Earth’s Systems
• The Carbon Cycle
(moves through the atmosphere,
biosphere, hydrosphere &
lithosphere)
– Photosynthesis and respiration.
– Plants and animals breathe
oxygen and return it to the air
and water as carbon dioxide.
– Large amounts of carbon are
stored in the form of Fossil
fuel (oil, coal, natural gas).
Burning fossil fuels releases
carbon into the atmosphere in
the form of Carbon Dioxide
(CO2)
– Large amounts of carbon are
also stored in tissues of trees
(such as wood). So, carbon
Dioxide (CO2) is also released
when wood is burned or when
it decays.
(Images from http://www.copperwiki.org/index.php?title=File:Oxygen_Cycle.jpg and
http://eo.ucar.edu/kids/green/cycles6.htm)