This course - Fundamentals of Atmospheric Science - has been compartmentalized into eleven lessons in order to aid your learning and to grow your analytical skills. But in the atmosphere, the fundamentals of atmospheric science work together to create the atmosphere that we observe. In this lesson, you will work to draw on your understanding of the atmosphere to explain an atmospheric observation that you have chosen. In addition, you will demonstrate your understanding of the lessons by taking a final exam that is made up of questions and problems from the eleven lessons. You will have worked some of the problems and answered some of the questions, but not all.
By the end of this lesson, you should be able to:
If you have any questions, please post them to the Course Questions discussion forum. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The atmosphere is one of the Earth's most efficient integrators. The atmosphere connects to almost every part of the Earth system—the lithosphere (i.e., solid earth), the hydrosphere (i.e., oceans), the cryosphere (i.e., ice), and the biosphere (i.e., life from microbes to plants to animals). The atmosphere's constituents are essential for life. The atmosphere transports energy and atmospheric constituents—in days it mixes air through the troposphere; in weeks it circumnavigates the globe; in months it transports air from the equator to the poles; in a year it shifts air from one hemisphere to another. The atmosphere and the water it contains shape the land with wind and water erosion, move the ocean currents, and determine where and when life can thrive or die. The atmosphere has shaped human history. For all of these reasons and more, the atmosphere, its governing principles, and its behavior must be thoroughly understood in a way that makes it possible to accurately predict its future behavior.
METEO 300 is designed to give you a solid understanding of the atmosphere's physical and chemical principles and the skills to quantify its behavior and properties. In the following table, the accumulated learning objectives are laid out end-to-end in an impressive array. If you have worked hard and completed all the exercises, you can know and can do what is in this table.
Lesson | Learning Objectives |
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12 |
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There are fifty-one learning objectives listed here. Read through this list and think about how comfortable you are with your knowledge and your abilities in each area. If you don't remember some of them, review them now.
The final project will test your ability to make an observation of the atmosphere and to provide an integrated analysis of that observation using the knowledge and quantitative analysis skills that you have learned in this course.
Because the atmosphere is changing at an unprecedented rate, it is fitting to have an alternative final project have an overall theme of “Our Changing Atmosphere.” Within this broad theme, there are many topics you can focus on, such as one of many aspects of anthropogenic climate change: forest fires, flooding, declines in ice (including snow cover, sea ice, and glacier), storm track changes, increases in extreme precipitation, changes in humidity, changes in hydrology (soil moisture, groundwater, and the flow of rivers), drought, and sea-level rise. Or you could focus on how anthropogenic climate change is influencing ecosystems, agriculture, or human health. Of course, there are many other ways the atmosphere is changing, many for the better, such as improvements in air quality and the recovery of the ozone layer. You could pick a particular place and/or a particular chemical species and report on changes. The atmosphere is also changing as a result of the way land is used, with the urban heat island being one of many relevant phenomena in this category. You might also focus on policy and technology aspects of atmospheric change, such as climate treaties and agreements, air quality regulations, geoengineering, carbon capture and sequestration, reforestation, and renewable energy systems. You could look at what different political parties in the U.S. and elsewhere have proposed to address our changing atmosphere. There are many possibilities, so pick a topic that you have been wanting to learn something about and that you can connect to course material. My suggestion - check out the newest Intergovernmental Panel on Climate Change (IPCC) report for inspiration.
Because the atmosphere is changing at an unprecedented rate, it is fitting to have an alternative final project have an overall theme of “Our Changing Atmosphere.” Within this broad theme, there are many topics you can focus on, such as one of many aspects of anthropogenic climate change: forest fires, flooding, declines in ice (including snow cover, sea ice, and glacier), storm track changes, increases in extreme precipitation, changes in humidity, changes in hydrology (soil moisture, groundwater, and the flow of rivers), drought, and sea-level rise. Or you could focus on how anthropogenic climate change is influencing ecosystems, agriculture, or human health. Of course, there are many other ways the atmosphere is changing, many for the better, such as improvements in air quality and the recovery of the ozone layer. You could pick a particular place and/or a particular chemical species and report on changes. The atmosphere is also changing as a result of the way land is used, with the urban heat island being one of many relevant phenomena in this category. You might also focus on policy and technology aspects of atmospheric change, such as climate treaties and agreements, air quality regulations, geoengineering, carbon capture and sequestration, reforestation, and renewable energy systems. You could look at what different political parties in the U.S. and elsewhere have proposed to address our changing atmosphere. There are many possibilities, so pick a topic that you have been wanting to learn something about and that you can connect to course material. My suggestion - check out the newest Intergovernmental Panel on Climate Change (IPCC) report for inspiration.
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I took this picture of southeastern Pennsylvania while flying to Atlanta, GA on 29 June 2015. The picture was taken at 14:30 EDT (18:30 UTC) from an altitude of about 20 kft. Note the fair weather cumulus clouds have little vertical development. Also, even though it was a fairly moist summer day, the boundary layer below the fair weather cumulus appears quite clear.
The presence of clouds indicates that three conditions existed: moisture, aerosol, and cooling. The moisture came from the surface, which had seen heavy rain a day before. Surface heating by solar visible irradiance evaporated liquid water on the surface, which created pockets of moist, buoyant air. These air parcels rose relative to the nearby less buoyant environment, according to the Buoyancy Equation [2.66]:
until they reached the lifting condensation level (LCL). There, they became supersaturated, so that the aerosol that forms the cloud condensation nuclei nucleated and cloud drops were formed according to the Koehler Theory Equation [5.13]:
These clouds sat in the entrainment zone just above the convective boundary layer. The energy budget for such a recently wetted land surface would likely show significant downward net radiation, and significant upward latent heat flux.
The clouds showed little vertical development. This behavior would suggest that the air was quite stable. Indeed, the radiosonde recording (Figure 1) from Dulles Airport a few hours earlier indicated that the air was quite stable, with the ascent on a moist adiabat from the Lifting Condensation Level 5–10 K below the ambient temperature.
This condition came about from the synoptic scale conditions, with high pressure over the region (Figure 2) suggesting downward vertical descent and divergence according to Equation [9.5]:
which, by adiabatic compression, would lead to clearing skies.
It is most likely that these clouds in the observation were formed by adiabatic ascent by random localized buoyant air parcels. However, there was a fairly uniform stratus deck just to the northeast of this location and some evidence that this air mass was moving to the west or southwest toward the location (Figure 3).
As this stratus deck was mixed with drier air (Lesson 5.3, Equation [5.4]), the cloud deck could have broken up into evaporating individual clouds. Likely the clouds in the observation were from both adiabatic ascent and the evaporation of the stratus cloud deck.
Often with clear skies the pollution levels are high and the boundary layer is filled with haze. However, the visibility is quite good in the picture. There is generally enough PM2.5 (particle matter less than 2.5 microns in diameter) present in southeastern Pennsylvania. However, rain the previous day was able to remove some of the pollution from previous days, thus clearing the air. In addition, the particles that were there may not have been swollen to a size that efficiently scatters solar radiation, when in Equation [6.18]:
the size of the particles are approximately equal to the visible wavelength. Indeed, we have at least three pieces of evidence that the air was fairly dry (Figure 1, Figure 3, and Figure 4 (Lesson 7)), with dewpoints in the middle-to-high 50s (oF) (see this image [4]).
From the skew-T, the relative humidity was only about 50% (Lesson 3.5, RH = w/ws = 7 g/kg / 14 g/kg). Thus, the recent scavenging of aerosol by heavy rain and the low relative humidity made for great visibility and clear boundary layer air even in the high pressure region, with light winds and clearing skies. This example is interesting because only after frontal passages with rain is the boundary layer air so clear under high pressure. If the high pressure were to persist, then the moisture levels would likely increase due to evaporation of surface water and the pollutant emissions and chemistry would make more particle pollution, both of which would lead to lower visibility in the boundary layer.
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This example meets the overall standards for integration and explanation of the observation. The analysis addresses the presence of the fair weather cumulus and the reason for the clear air in conditions when the visibility is often not so good. On the other hand, my example would not receive a perfect score for a few reasons. First, the choice of observation is good but not very interesting. Second, all of the equations are appropriate, but some are not well integrated into the analysis. Third, some of the figures are fuzzy. And, fourth, the possible evaporation of the stratus deck is not particularly well explained.
For your reference, the grade for this example would likely be 11 to 12 on a scale of 15.
(20% of final grade)
Evaluation | Explanation | Available % Points |
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Not Completed | Student did not complete the assignment by the due date. | 0 |
Student completed the project with little attention to detail or effort. | Project is on a weak observation, has flawed analysis, and/or lacks a clear presentation. In addition, there is inadequate evidence of integration of course material, no references to equations that would help quantify the observation, or no/poor figures to support analysis. | 3 |
Student completed the project, but it has many inadequacies. | Project is strong in one or two of the following areas but weak in the rest: good choice of observation, thorough analysis and evidence, conclusions supported by evidence, draws evidence from at least five different lessons, includes at least three different equations needed to do a quantitative analysis, contains figures/graphs taken from other sources to provide evidence and support conclusions, organization is logical, and presentation is clear and concise. | 6 |
Student completed a pretty good project, but it had some inadequacies. | Project is strong in more than half of the following areas but weak in the rest: good choice of observation, thorough analysis and evidence, conclusions supported by evidence, draws evidence from at least five different lessons, includes at least three different equations needed to do a quantitative analysis, contains figures/graphs taken from other sources to provide evidence and support conclusions, organization is logical, and presentation is clear and concise. | 9 |
Student completed a very good project, but it had a few inadequacies. | Project is strong in all but a few of the following areas: good choice of observation, thorough analysis and evidence, conclusions supported by evidence, draws evidence from at least five different lessons, includes at least three different equations needed to do a quantitative analysis, contains figures/graphs taken from other sources to provide evidence and support conclusions, organization is logical, and presentation is clear and concise. | 12 |
Student completed an excellent final project with no serious inadequacies. | Project is strong in all of the following areas: good choice of observation, thorough analysis and evidence, conclusions supported by evidence, draws evidence from at least five different lessons, includes at least three different equations needed to do a quantitative analysis, contains figures/graphs taken from other sources to provide evidence and support conclusions, organization is logical, and presentation is clear and concise. | 15 |
The final examination will be comprehensive. The goal of this exam is to test you on your competence in relation to the course learning objectives.
The final exam will consist of questions and problems from the quizzes that you have taken throughout the course. That does not mean that all of the questions and problems on the exam will be ones that you have already solved. That is because each quiz consisted of more questions and problems than you were actually given. The ones you answered were randomly selected from larger banks of questions and problems. The questions and problems that you receive on the exam should be similar in objective and level of difficulty to the ones that you have already answered in the quizzes.
The final exam will be taken within the time frame given in the final exam assignment module. You may use any books, online materials, including practice quizzes, quizzes, etc. But do not consult a classmate or any other student for help on the exam. Do not share the exam or the answers with anyone else. Violating these rules will result in your failing the class. So, just follow the rules.
Congratulations. You have completed METEO 300, Fundamentals of Atmospheric Science. You are now ready to build even more understanding and more skills on top of the ones that you have mastered here.
Lesson 12 was designed to see how well you could take all of this information and use it to synthesize solid explanations of atmospheric observations. The atmosphere integrates processes that occur on scales ranging from the microscale to the global scale; now maybe you appreciate the significance of this integration and how essential it is to a true understanding of the atmosphere, climate, and weather.
Hopefully, you will now have the confidence to analyze explanations offered by others for atmospheric phenomena and determine if those explanations are correct or not. Believe me, even experts sometimes provide answers that don't hold water. So when you read or hear something that doesn't sound right, dig into it and come to your own conclusions.
Hopefully you will now be fascinated by observations of the atmosphere and its amazing transformations, and will try to figure out what is happening and why. If you see something wonderful and would like to share it, I'd be happy to talk to you about it, even after the class has ended.
You have reached the end of Lesson 12! Double-check that you have completed all of the activities.