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This is a powerpoint covering some of the main points of the earth's sources of internal and external energy. 9th Grade honors Physical Science covers this area very briefly.
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Internal and External Sources of Energy by Emily Block and Lindsey LaBrie
Earth's Energy Sources
-Earth gets its energy in two ways:
-Internal (radioactive decay and gravitational energy)
-External (the sun)
Earth's Early Internal Energy
-Far greater than what it is now due to 3 intense processes:
-Extraterrestrial Impacts (comets, meteors, etc)
-Gravity
-Radioactive Decay
Extraterrestrial Impacts
-Includes meteorites which contained iron and stone, and comets
-When these things impacted the earth, they added mass as well as size
-This increase in size lead to a greater gravitational force
Gravity (Gravitational Energy)
-As the force of gravity increased within the earth, gravitational energy made the earth more compact, which turned into heat energy
-Rocks are not good conductors of heat, and that is why the core is much hotter than the crust-The heat that is present in the core cannot escape quickly
-Early earth had many more radioactive elements than today, which means its core used to be a lot hotter
-Radioactive elements break down over time and release heat
-Some elements have a longer decay rate than others, so they are still releasing heat energy in the core
What Internal Energy Does
-Moves the continents around the globe
-Forms volcanoes and mountain ridges
-Causes earthquakes
Volcanoes
-Volcanoes are openings in Earth's crust that release molten lava, ash, and gases.
-The molten rock is magma while under ground and it is lava when it is above ground.
-Materials put off during a volcanic eruption:-Lava, Water vapor, Hydrogen sulfide, Carbon dioxide,
volcanic bombs, lapilli (rock fragments), and ash.
4 Types of Usable Internal Energy
-Chemical-Nuclear-Geothermal-Rotational (least usable)
Internal Energy
-Results from the breaking down of radioisotopes over time
-Drives plate tectonics due to conduction
-Renews the surface of the Earth
External Energy
-The Earth gets its external energy from the sun
-The sun radiates its energy in all directions so only a small fraction of it reaches the Earth-On a sunny day, the planet receives 1,350 Joules of energy per second.
-Sun's radiation is sufficient enough to run Earth's processes
Solar Radiation
-Only 51% of the solar radiation that reaches the Earth is absorbed by the surface
-19% is absorbed by the atmosphere
-16% by gases and dust-3% by clouds
-30% is lost in space-24% is reflected upward-6% is scattered upward
Radiation
-The numbers on the chart are an average for the Earth as a whole
-Different materials reflect things in different ways
-Shiny and light-colored objects reflect more radiation than dark-colored objects
Albedo
-An albedo is the amount of radiation an object reflects
-Snow reflects 90% of the radiation that hits it, it absorbs the rest. Therefore, snow has an albedo of 0.9
-A dark forest reflects 5% of the radiation that reaches it, so it has an albedo of 0.05
Runaway Albedo Effect
-If the entire Earth were to be covered in ice, it would take a great amount of time for it to all melt away.
-If the Earth were a ball of ice, the volcanic systems would continue to produce and give off carbon dioxide.
-The carbon dioxide would soon fill up our atmosphere and make the snow and ice melt away.
-The process of filling the atmosphere with CO2 would take millions of years.
Citations
-Earth's Energy Budget. N.d. Photograph. Docstock.com. Malj, 14 July 2011. Web. 29 Apr. 2013.
Global Sources of Energy. N.d. Photograph. etap.orgWeb. 30 Apr 2013.-"Internal and External Energy; Energy Budget." Earth Science Lesson 4--Energy in
the Earth System. N.p., n.d. Web. 29 Apr. 2013.-Schuller, Jason. "Rock Of Ages." Wreckroom. N.p., n.d. Web. 02 May 2013.-Simmons, Marty. "External Sources of Energy of the Earth." EHow. Demand Media,
28 Mar. 2011. Web. 01 May 2013.-Sun and Earth Images. 2013. Photograph. hdwallpaperspics.comWeb. 30 Apr 2013.
-Tariq, Malik. "Giant Sun Eruption Captured in NASA Video -- Science & Technology -- Sott.net." SOTT.net. Space.com, 17 Nov. 2012. Web. 07 May 2013.
-"The Earth's Heat Furnace." How Volcanoes Work. N.p., n.d. Web. 30 Apr. 2013.
-The Rock Scientist. "Earth As A Snowball Part 3." Mind Blowing Science. N.p., 10 May 2012. Web. 08 May 2013
-"Unit 8: The Earth's Internal Energy." Unit 8: The Earth's Internal Energy. Slideshare, n.d. Web. 07 May 2013.
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