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

• 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.

Many processes occur in patterns within the 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.

Lesson #8 Earth’s Systems

(Images from http://ga.water.usgs.gov/edu/graphics/watercyclesummary.jpg and http://dnr.wi.gov/org/caer/ce/eek/earth/groundwater/watercycle.htm)

• 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

Lesson #8 Earth’s Systems

(Image from http://www.kidsgeo.com/geography-for-kids/0161-the-nitrogen-cycle.php and http://www.h2ou.com/h2nitrogencycle.htm)

• 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.

Lesson #8 Earth’s Systems

(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)

• 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.

Lesson #8 Earth’s Systems

(Images from http://www.copperwiki.org/index.php?title=File:Oxygen_Cycle.jpg and http://eo.ucar.edu/kids/green/cycles6.htm)