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

What it May Have Looked Like...

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.