Subject: Earth Science

Atmosphere

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· Lesson Objectives

· The student will investigate and understand the origin and evolution of the atmosphere and the interrelationship of geologic processes, biologic processes, and human activities on its composition and dynamics.

· key concepts include scientific evidence for atmospheric changes over geologic time

· current theories related to the effects of early life on the chemical makeup of the atmosphere

· comparison of the Earth’s atmosphere to that of other planets

· atmospheric regulation mechanisms including the effects of density differences and energy transfer

· potential atmospheric compositional changes due to human, biologic, and geologic activity

· What is the atmosphere?  What does it do? How was it formed?

 

Watch this video to give you a preview of what we will learn in this lesson. 

Here are 25 Amazing Facts about our atmosphere!

 

 

When the Earth was first formed, the gases released by various processes were probably stripped away by the Sun's solar winds, but eventually a state was reached where the atmosphere remained. This atmosphere would have seemed very thick compared to today's atmosphere, with about 80% of it made up of water vapor. This water vapor would have been released as rainfall, and created the oceans.

 

Water sediments have been found that date back as far as 3.8 billion years ago. Studying these sediments can tell us much about the content of the Earth's atmosphere. Just after our first known early life forms, at about 3.5 billion years ago, the atmosphere seems to have stabilized as a nitrogen rich matter. The balance of living organisms, shifting land masses, and the content of the atmosphere slowly changed until there was an oxygen component to the atmosphere, which grew. Today's atmosphere is mostly nitrogen (about 78% in dry air) and oxygen (about 21% in dry air), with some other elements, such as carbon, also getting into the mix.

 

 

There was a long period of time when Earth's atmosphere did not contain oxygen. It is theorized that many of the processes where organisms now use oxygen at one time used sulfur instead. Studying the chemical make-up of rock beds can give scientists information about what compositions were available in the air. In the past, there was probably a lot more carbon dioxide in the atmosphere, but since carbon dioxide is water soluble, it gets washed down by rain. Also, plant life uses carbon dioxide during photo-synthesis, and releases oxygen, which helps explain the growing oxygen component.

 

 

Unlike several of our neighboring planets, the Earth's atmosphere has a way of balancing the amount of carbon dioxide in the atmosphere: The carbon cycle, or the carbon-silicate cycle. As rain falls, it pulls carbon dioxide from the air and deposits it into the oceans. Sea creatures use the carbon (usually in combination with calcium and other minerals) and then when sea creatures die, the carbon compounds wind up as sediment at the bottom of the ocean. The ocean floor is seismically active, which brings these compounds into the mantle, where they can be re-released only by volcanic activity.

 

Atmospheric Layering

The atmosphere has five distinct layers, each with different chemical compositions, different temperatures, and different densities. The layers are known as the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere.

 

The troposphere is the layer closest to the ground. It extends about 12 miles above the Earth's surface at the equator, but only about 4 miles above the Earth's surface at the poles. The troposphere has the right composition, pressure, and temperatures to make life on Earth (as we know it) possible. The further away from the Earth one goes, or the higher the elevation, the thinner and colder the air gets. Since the air is colder up higher, and heat rises, this means that there is likely to be a lot of air movement in this layer. It is also where all weather takes place.

 

See the different layers of the atmosphere and what each one does:

 

Volcanic Effects

 

As mentioned earlier with the carbon-silicate cycle, magma is one repository of dissolved gases. It is also one of our largest sources of water. Magma is compacted into an extremely dense state under the surface of the Earth, such that when it is explosively released it takes up much more space on the surface of the Earth than it does underground. According to the U.S. Geological Survey, "if one cubic meter of 900°C rhyolite magma containing five percent by weight of dissolved water" were brought up to the surface in an instant, that "one cubic meter of magma now would occupy a volume of 670 m3 as a mixture of water vapor and magma at atmospheric pressure."

 

The biggest release from a volcanic eruption is that of water vapor, but there can also be large amounts of carbon dioxide and sulfur dioxide. Aside from the immediate dangers of eruptions, scientists have found that volcanic eruptions can also affect climate.

 

"Measurements from recent eruptions such as Mount St. Helens, Washington (1980), El Chichon, Mexico (1982), and Mount Pinatubo, Philippines (1991), clearly show the importance of sulfur aerosols in modifying climate, warming the stratosphere, and cooling the troposphere. Research has also shown that the liquid drops of sulfuric acid promote the destruction of the Earth's ozone layer." (USGS, "Volanic Gases and Their Effects")

 

 

The Human Factor

 

There has been some concern over the effect that human activity can have on the atmosphere. Modern man has developed many technological advances that release gases into the atmosphere that would otherwise not be present, or release gases in greater quantities than would otherwise occur. If this has an effect on the climate of the Earth it could be dangerous, over the long term, to the delicate balances that support life.

 

"Scientists have calculated that volcanoes emit between about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere every year (Gerlach, 1999, 1991). This estimate includes both subaerial and submarine volcanoes, about in equal amounts. Emissions of CO2 by human activities, including fossil fuel burning, cement production, and gas flaring, amount to about 27 billion tonnes per year (30 billion tons) [ ( Marland, et al., 2006) - The reference gives the amount of released carbon (C), rather than CO2, through 2003.]. Human activities release more than 130 times the amount of CO2 emitted by volcanoes--the equivalent of more than 8,000 additional volcanoes like Kilauea (Kilauea emits about 3.3 million tonnes/year)! (Gerlach et. al., 2002)." (USGS, "Volanic Gases and Their Effects")

 

For more info: https://volcanoes.usgs.gov/vhp/gas_climate.html

 

 

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Bonus Content (This section is not required)

If you are interested in more information about some of the topics from the lesson OR if you need help with some of the questions, you can watch these  OPTIONAL  (you can watch if you want but they are not required) v ideos for help!

 

See what the formation of the atmosphere might have looked like:

 

How does the earth's atmosphere compare to the other planets in our solar system?

 

Venus

 

Mars

 

The Outer Planets

What does the atmosphere do?

Why is there life on earth? What does this have to do with Goldilocks?

See how heat is transferred in the atmosphere through convection currents:

 

 

What is air pressure, how is the uneven heating of the atmosphere important, and how does it impact weather?

 

 

What do humans do to impact the atmosphere?

 

What happens if Earth loses its atmosphere?

· Grading Rubric

Rubric Earth Science Lesson 10

 

Note: For this class it is necessary to post each question, then the work/explanation, then the answer. Failure to do so will result in asking for a revision. No grade will be given for incomplete work.

Mastery of this lesson will be determined when your total points are 8 or higher. Revisions will be requested when your total points are below 8. Points are earned according to the chart below.

10:  A total score of 10 on your first submission, or within the first revision.

9.5: A total score of 9.5, or all questions are correct after the first revision.

9:    A total score of 9.

8.5: A total score of 8.5.

8:    A total score of 8.

 

Short answer Total content points= 8	All parts of all questions are answered in complete sentences.   1 points each	Questions are answered in complete sentences. Not all parts of each question are answered.   0.5 points each	Questions are not answered in complete sentences and/or are missing responses for questions.     0 points
Apply Your Knowledge Total content points=2	Questions are thoroughly answered in complete sentences and in the student’s own words. URLs are included for outside research.    1 point each	Questions are answered but may have incomplete responses or contain minor errors. Responses are in the student’s own words. URLs are included for outside research.     0.5 points each	Questions contain inaccurate information and/or are not written in the student’s own words. URLs for outside research are not provided.       0 points

 

· Assignment

 

Do not submit text that you have copied from sources, including websites. All of your work should be in your own words. Using copied text would be considered plagiarism. For more information, review our page on  Plagiarism and Citation . Cite the complete web page source under each answer.  Always put the question on top of the answer, and answer in complete grammatically correct sentences.

 

 

Many of these answers will require Internet research to answer. Make sure you rewrite all answers into your own words and be mindful of our page on  Plagiarism and Citation .

 

 

Short Answer

 

1. Find out a little more about the layers of the atmosphere.

 

a. Which layer is the largest? How large is it?

b. Where is the ozone layer located? Why is the ozone layer important?

c. What is the outermost layer called? About how far above the Earth does it reach?

 

2. What is the atmosphere of Venus like, and how does it compare with Earth's atmosphere?

 

3. What is the atmosphere of Mars like, and how does it compare with Earth's atmosphere?

 

4. How are the atmospheres of the inner planets different from the atmospheres of the gas giants?

 

5. What is the "Goldilocks Effect" when discussing Earth?

 

6. One important thing that happens in Earth's atmosphere is known as heat transfer. In this context, find out what convection is and tell me briefly about it here. Explain why this movement occurs.

 

7. About what percentage of the atmosphere is made up of water vapor today?

 

8. What is atmospheric pressure?

 

Apply Your Knowledge

 

9. What does it mean when barometric pressures rise and fall? What is the weather like when it rises? What is the weather like when it falls?

 

10. Name two things humans can do to minimize the impact their technologies have on the atmosphere.

 

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