Published on METEO 300: Fundamentals of Atmospheric Science (https://www.e-education.psu.edu/meteo300)

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Lesson 12: The Atmosphere - A Holistic View

Overview

Overview

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.

Learning Objectives

By the end of this lesson, you should be able to:

  • explain the physical and chemical phenomena that are responsible for an observation of the atmosphere
  • demonstrate your mastery of the course learning objectives

Questions?

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.

12.1 An Integrated View of the Atmosphere

12.1 An Integrated View of the Atmosphere

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.

METEO 300 Learning Objectives
Lesson Learning Objectives
1
  • correctly use significant figures, dimensions, and units
  • solve simple problems using integral and differential calculus
  • prepare and use a course Excel workbook for course calculations
2
  • use the fundamental gas laws—Ideal Gas Law and Dalton’s Law—to determine the relative densities of different air masses
  • derive the hydrostatic equilibrium equation from force balance to show why atmospheric pressure decreases with height
  • use the 1st Law of Thermodynamics and conservation of energy (i.e., adiabatic processes) to explain air parcel temperature changes
  • determine stability for different dry environmental temperature profiles
  • calculate buoyancy and vertical velocity with time
3
  • differentiate among the different ways that moisture can be expressed and choose the correct one for finding an answer to a given problem
  • explain the meaning of the lines and spaces on a water vapor phase diagram
  • calculate relative humidity using the Clausius–Clapeyron Equation
  • solve energy problems related to temperature and phase changes
  • demonstrate proficiency with using the skew-T diagram to find the lifting condensation level (LCL), potential temperature, relative humidity, wetbulb temperature, dry and moist adiabats, and equivalent potential temperature
4
  • explain the role that each atmospheric constituent plays in atmospheric structure and weather
  • identify changes in minor and trace gas amounts and the impacts these changes have on the atmosphere
  • explain how the atmosphere cleanses itself, using methane as an example
  • use chemical equations to show how ozone is formed in the stratosphere and the troposphere and how they differ
  • diagram the lifecycle of aerosol particles with an emphasis on their role in weather
5
  • identify cloud types
  • describe the essentials for cloud formation
  • on a Koehler curve, explain the behavior of a particle in different supersaturation environments
  • explain the lifecycle of cloud formation through precipitation
6
  • identify the causes of changing solar radiation on Earth
  • calculate properties of the spectrum of solar and Earth radiation in terms of the Planck function
  • calculate the absorption between you and a light source
  • explain why the sky looks blue and hazy in the summer
7
  • demonstrate the effects of infrared absorbers on Earth’s temperature using a simple model
  • explain the concept of radiative–convective equilibrium
  • determine what a satellite is seeing by interpreting the observed spectrum of upwelling infrared radiation
8
  • calculate partial derivatives
  • implement vector notation, the dot product, the cross product, and the del operator
  • explain the different coordinate systems and how they are used
  • convert between math and meteorological wind directions
  • calculate temperature advection at any point on a map of isotherms (lines of constant temperature) and wind vectors
9
  • identify regions of convergence, divergence, positive vorticity, and negative vorticity on a weather map
  • calculate the strength of the different flow types from observations
  • relate vertical motion to horizontal convergence and divergence
10
  • explain mass conservation physically, recognize the mass conservation equation, and memorize its form when density is constant
  • state the three main conservation laws in atmospheric science: the conservation of mass, the conservation of momentum, and the conservation of energy
  • name and explain the three fundamental (real) forces in the atmosphere (gravity, pressure gradient, and friction)
  • name and explain the two new (apparent) forces that emerge when momentum conservation is written in the rotating reference frame
  • draw the balance of forces for geostrophic flow, gradient flow, geostrophic flow with friction, and cyclostrophic flow
  • explain why midlatitude winds are westerly
11
  • draw the PBL and its diurnal variation
  • perform Rayleigh averaging on an equation and derive an equation for the turbulent parts
  • explain kinematic fluxes
  • show vertical motion using eddy fluxes
  • explain turbulent kinetic energy (TKE) and its behavior
  • sketch the surface energy budget for different conditions
12
  • explain the physical and chemical phenomena that are responsible for an observation of the atmosphere
  • demonstrate your mastery of the course learning objectives

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.

12.2 The Final Project

12.2 The Final Project

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.

Procedure to Complete Final Project - Online Meteo 300 only

  1. Choose an observation of the atmosphere. The observation could be a picture, video, radar image, satellite image, or figure. It can come from you, the course material, a site that allows copying, or a family member or friend. Do not use an observation that has been previously analyzed by anyone else. When you are choosing an observation, think about the story you want to tell and how well you think you can tell it. You will want to do a little research and maybe think about two or three different possibilities before you settle on one.
  2. Check to make sure that your observation is at a time and place for which you can get weather information (e.g., temperature, relative humidity, pressure, weather maps, weather station model, upper air data) that you will need to analyze and explain your observation.
  3. Before you start the analysis and writing, put your idea for your final project in the Final Project Ideas drop box. I will look at your idea and let you know if I think it is not too big and not too small but just right. You can submit the observation itself at this time but that is not necessary.
  4. Gather the evidence as you build your analysis of the observation. Be sure to document where your evidence came from.
  5. First show and describe the observation. You should give as much information as you have about the observation – what, where, and when it was observed.
  6. Write your analysis in formal language, such as you might see in a science news magazine and is in the example below. You can submit this analysis as a Word or pdf file. The length could be as short as a few pages, including figures, graphs, and equations, but it must be thorough and complete. 
  7. Be thorough but concise.
  8. After you have completed your final project, go back through it and edit it. Make it as polished and appealing as possible.
  9. Follow the instructions below for submitting it in Canvas. Late presentations will have points deducted.
    1. Put your final project in either Word or PDF format.
    2. Embed pictures and equations in the text.
    3. Name your file "Final_Project_YourLastName".
    4. Submit it to the Final Project assignment which is located in the Lesson 12 Module in Canvas.
  10. Follow the instructions below for submitting it in Canvas.

Procedure to Complete Final Project - Resident Meteo 300 only

  1. Choose an observation of the atmosphere. The observation could be a picture, video, radar image, satellite image, or figure. It can come from you, the course material, a site that allows copying, or a family member or friend. Do not use an observation that has been previously analyzed by anyone else. When you are choosing an observation, think about the story you want to tell and how well you think you can tell it. You will want to do a little research and maybe think about two or three different possibilities before you settle on one. Try to think of observations that are unique and interesting.
  2. Check to make sure that your observation is at a time and place for which you can get weather information (e.g., temperature, relative humidity, pressure, weather maps, weather station model, upper air data) that you will need to analyze and explain your observation.
  3. Before you start the analysis and writing, put your idea for your final project in the Final Project Ideas drop box. I will look at your idea and let you know if I think it is not too big and not too small but just right. You can submit the observation itself at this time but that is not necessary.
  4. Gather the evidence as you build your analysis of the observation. Be sure to document where your evidence came from.
  5. First show and describe the observation. You should give as much information as you have about the observation—what, where, and when it was observed.
  6. Then make a 5-minute PowerPoint presentation of your observation and your analysis. The length could be as short as a few slides, including figures, graphs, and equations, but it must be thorough and complete. I suggest that you use anywhere from three to about six slides, depending on the number of figures you need to describe your analysis. Put in another slide with your references to websites, books, and papers on it. You do not have to do a quantitative analysis, necessarily, but if you do, your analysis will be more impressive and convincing.
  7. Be thorough but concise.
  8. After you have completed your final project, go back through it and edit it. Make it as polished and appealing as possible.
  9. Follow the instructions below for submitting it in Canvas. Late presentations will have points deducted.
    1. Put your final project in either PowewrPoint or PDF format.
    2. Embed pictures and equations in the text.
    3. Name your file "Final_Project_YourLastName".
    4. Submit it to the Final Project assignment which is located in the Lesson 12 Module in Canvas. 
  10. Presentations will run for two weeks. I will select the order of the presentations using random numbers, so you will need to attend all the classes. I will also take role during each class and will deduct participation points for students who do not have a valid excuse approved by me to miss class. It is only fair to the students who are presenting near the end that the audience is as big for the last presentation as it is for the first.

____________________________________________________________

Example of a Final Project for on-line instruction - other examples of residence instruction Powerpoints are given in Canvas.

Observation

Airplane view of the ground in southeastern Pennsylvania

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.

Explanation

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]:

B= ( T v ' − T v ) T v g 

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]: s k = S k −1= a K r d − Bi N s r d

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.  

Skew-T image from June 29, 2015. See caption.
Figure 1. Skew-T from nearby Dulles International Airport on 29 June 2015.
Credit: NWS data, University of Wyoming skew-T website [1]

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]:

∂w ∂z = − ∇ → H • U → H MathType@MTEF [2]@5@5@+=faaahmart1ev3aaaKnaaaaWenf2ys9wBH5garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=ribbf9v8qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9q8qqQ8frFve9Fve9Ff0dc9Gqpi0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqqaaaaaaaaGySf2yRbWdbmaalaaapaqaa8qacqGHciITcaWG3baapaqaa8qacqGHciITcaWG6baaaiabg2da9iaacckacqGHsislcuGHhis0paGbaSaadaWgaaWcbaWdbiaadIeaa8aabeaak8qacaGGIaIabmyva8aagaWca8qadaWgaaWcbaGaamisaaqabaaaaa@416E@

which, by adiabatic compression, would lead to clearing skies.

Surface weather map for June 29, 2015. See caption.
Figure 2. Surface weather map for 29 June 2015. Note the surface high pressure region over northern Virginia.
Credit: NOAA [3]

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).

Visible satellite image for June 29, 2015. See caption.
Figure 3. Visible satellite image for 29 June 2015. Note the breaking cloud cover in the Northeast and the fair weather cumulus over much of Pennsylvania and Maryland.
Credit: NOAA [4]

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 [6.17]:

x≡ 2πr λ

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 [5]).

Satellite vapor image for June 29, 2015. See caption.
Figure 4. Satellite water vapor image for 29 June 2015. Note the tongue of fairly dry air going across western Virginia into Maryland and southeastern Pennsylvania.
Credit: NOAA [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.

_________________________________ 

Self Evaluation of This Example. Note: This evaluation is given here to show you how the rubic will be used to evaluate your project. You should not include a self-evaluation with your project.

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.

Final Project

(15% of final grade)

  1. The final project is worth 15% of your final grade.
  2. I will use the following rubric to grade your final project:
Final Project Grading Rubric
Evaluation Explanation Available % Points
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

12.3 The Final Comprehensive Examination

12.3 The Final Comprehensive Examination

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 opened for you on a date to be announced in class or by email and closed several days later. I strongly recommend that you finish and submit your final project and then take the final exam. I am giving you several days to complete the exam—that should be enough time even if you need to fit it in around other obligations. You may use any books, on-line materials, including practice quizzes, quizzes, etc. But do not consult a classmate or any other student for help on the exam.

Summary and Final Tasks

Summary

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.

Reminder - Complete all of the Lesson 12 tasks!

You have reached the end of Lesson 12! Double-check that you have completed all of the activities.


Source URL: https://www.e-education.psu.edu/meteo300/node/698

Links
[1] http://weather.uwyo.edu/upperair/sounding.html
[2] mailto:MathType@MTEF
[3] http://www.wpc.ncep.noaa.gov/dailywxmap/
[4] http://www.goes.noaa.gov/
[5] http://www.wpc.ncep.noaa.gov/dailywxmap/dwm_stnplot_20150722.html