Homework 6. Chapter 4. (In class problem, not turned in).
Purpose:
Work with the direct, diffuse, and total radiation reflected and transmitted by clouds, and the role of multiple scattering.
Problem 1
You may copy the problem statement and questions to Microsoft Word and put your answers there to follow along.
The Mie theory calculator link will need to be used for this problem.
Here are the class notes for this problem:
Single scattering properties of a single cloud droplet discussion (right click, save, open with OneNote).
Multiple scattering properties of a cloud of droplets discussion (right click, save, open with OneNote).
Problem Statement:
A stratiform cloud fills the sky.
The cloud is 1 km thick, and is a water droplet containing cloud composed of a monodispersion of droplets all having radii = 7 microns.
Assume the droplet single scattering albedo is 1 (no absorption of radiation).
The optical depth at 550 nm is τext=τsca=10, for green light. Note that 550 nm = 0.55 microns.
Questions.
a. What is the size parameter?
b. What scattering regime is this?
c. What is the scattering efficiency factor? (Mie theory calculator).
d. What is the asymmetry parameter? (Mie theory calculator).
It is also known as the average cosine of the phase function.
e. What is the number concentration of cloud droplets?
[Hint: Calculate this from the given optical depth and the relationship with number concentration.]
f. What fraction of direct sunlight makes it through this cloud?
g. What fraction of total radiation (diffuse and direct) makes it through this cloud?
h. What fraction is the diffuse radiation to the total radiation coming through this cloud?
i. Would the sun be visible when viewed through this cloud? Briefly discuss your answer.
j. What is the liquid water path for this cloud? (total liquid water per unit area).
k. How much water would be collected in a cup of area A swept through the cloud?
(In other words, what is the precipited water in mm, similar to precipitable water vapor).
L. What is the total reflectance of this cloud if it is placed over a surface that has an albedo A=0.3?
(This problem includes multiple reflection between the cloud and the ground).
Resources for Problem 1:
Model to calculate light scattering and absorption by spherical particles, also known as "Mie Scattering" for the person that developed it.
Theory of multiple scattering in one dimension (an excellent discussion).
Single scattering properties of a single cloud droplet discussion (right click, save, open with OneNote).
Multiple scattering properties of a cloud of droplets discussion (right click, save, open with OneNote).
Homework 5. Chapter 4.
Turn in this homework assignment through webCampus, prepared using Microsoft Word.
Purpose:
Observe how relatively simple analysis can lead to climate insight concerning the Earth's radiatian budget and response time to climate change.
Have a deeper understanding of something we overlook in our daily lives, the blueness of the sky and the polarization of sky light.
Appreciate the radiation deficit from the equator to the poles.
Read chapter 4. The first two problems are related to climate and radiation issues.
1. Do problem 4.21.
Notes on this problem (right click on link and save to disk. Open with OneNote).
Notes on the problem in PDF format.
Measurements of the Earth's spherical albedo as by Finnish researchers, from the NOAA Deep Space Climate Observatory. Data portal. Lagrange points and satellite location.
2. A. Do problem 4.29. Express your answer for the response time in units of days.
B. Estimate also the response time for the Earth's oceans taken together as one body of water. Express your answer in units of years.
Notes on problem discussion.
3. A. What is the ratio of Rayleigh scattering strength for blue light compared with red light by gases in the atmosphere? (You specify wavelengths).
B. How does this affect the color of the sky?
C. Describe the polarization of light seen when looking at 90 degrees from the direction of the sun on a clear day (no clouds or aerosol, just air).
See slides 77-81 and 95-97. Also see this image of the dipole radiation pattern.
If you have polarized sunglasses you can go out and look at the sky at 90 degrees from the sun direction, and rotate the sunglasses to see this effect (don't look directly at the sun!).
Additional Resources: Sky color discussion.
4. Do problem 4.56. This problem is intended to help you think about the Earth's radiation budget shown in Figures 4.34 and 4.35.
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Homework 4. CAPE AND SEVERE WEATHER
Chapter 3 and Section 8.3 on deep convection.
Deliverables:
1. Turn in this homework assignment through webCampus, prepared using Microsoft Powerpoint.
2. Do an oral presentation.
Purpose:
Become familiar with soundings that can be, but are not always, associated with severe weather and tornado outbreaks.
Investigate stability of the atmosphere using potential temperature and equivalent potential temperature.
Become familiar with reanalysis data for evaluating previous weather events.
Learn how to obtain and interpret archived radar and infrared satellite imagery.
Practice science communication through giving a presentation on this topic.
Preparation: for this homework includes our class discussions,
the MetEd module from the online homework Principles of Convection 1: Buoyancy and CAPE,
and reading section 8.3.1a on Deep Convection, pg 344-347 (or to pg 371 as time permits) of Wallace and Hobbs.
Also, as time permits, go through the MetEd modules on Principles of Convection 2: Using Hodographs and Principles of Convection 3: Shear and Convective Storms. They don't have to be turned in.
Steps A-G guide you through acquiring your data and intrepreting it.
That's followed by presentation instructions.
A. Find an exciting sounding (using the Univ. of Wyoming site) from anywhere in the continental US, after February 28th, 2017, with a lot of convective available potential energy (CAPE).
The limitation on date comes from the availabilty of satellite imagery.
Preferably find a sounding that was associated with severe weather in the vicinity.
Use archived radar data, or this if the first link doesn't work, for obtaining a quick look at precipitation in the vicinity in time and location of your sounding.
Use also NASA AQUA MODIS for around 2 pm local time quick-look at the area. The city name and state can be used in the search bar.
Here are some tools to use when choosing a site:
Tornado observations.
Tornado, wind, and hail events.
Tornado tracks.
Derechos.
List of derecho storms.
Hurricanes. Look under educational resources.
Upper air soundings, Univ. of Wyoming.
Map of upper air sounding locations where weather balloons are launched.
Obtain and save both the GIF skew T image and the text file.
The text file will be used for analyzing the sounding, for graphs and for reading values from it.
Color your sounding using the Paint program (or other) to illustrate the level of free convection, equilibrium level, LCL,
and regions of positive and negative buoyancy (green for positive, red for negative).
Here's an example.
Check your sounding for issues like these.
I will be using the Reno 3 July2021 0Z
sounding for the in-class example, so this one is not available for use. Local backup.
Text for the sounding. Local backup.
B. Identify the level of free convection and the equilibrium level.
These can be read from the sounding indices, or at the intersections given by the lifted surface parcel and environmental air.
C. Note and discuss the CAPE, CIN, and precipitable water from your sounding.
Calculate and report the maximum vertical updraft speed in m/s and mph.
wEL=(2CAPE)1/2. Here EL is the equilibrium level.
D. Make a graph of the vertical distribution of potential temperature (THTA in the sounding text) and equivalent potential temperature (THTE in the sounding text).
In your discussion, identify stable, unstable, neutrally stable, and convectively unstable regions.
Here's an example; the top height is at just above the equilibrium level.
Plotting these to just above the equilibrium level (and not the top of the sounding) allows us to see the details in the troposphere.
E. Obtain the 500 mb height map from reanalysis for your sounding for the time of the sounding, and including the location of your sounding.
Here is the link for reanalysis data. Settings example.
The latitude and longitude range for your graph can be centered at the balloon observation by finding the latitude and longtitude for it, and going +-20 degrees north and south, and west and east for the bounding box.
Interpret in terms of locations of low and high heights, and wind speed maxima and minima.
Compare the 500 mb wind speed and direction at your location (that should be the map center) with the sounding value at 500 mb.
Here's an example from the 28July2017 0z, Lamont Oklahoma located at about 36.62 North and 97.48 West: Settings and 500 mb plot example. Lamont Oklahoma is in the center of the image.
Lamont OK is site location 74646.
Draw an arrow showing the 500 mb wind direction at your site (center of the graph) based on the height contour spacings and compare with your sounding wind speed and direction at 500 mb. (Extra credit: do the same with a 1000 mb, 850 mb, 700 mb, and/or 250 mb map as well.)
It may be helpful to visualize the wind to use the Earth Winds viewer to see the atmospheric circulation at 500 mb near your location. Click on the Earth icon on the bottom left; choose the 500 mb level, and the date of your event. Then zoom in on your location, leaving room to see what's going on near it. Click on where you think the location is, and notice the latitude and longitude of that point. Click until you get the green circle to be centered close to the latitude and longitude given for your location on the sounding in the top right corner. CAPE can be overlain with the image.
F. Obtain the radar data for your location and its vicinity, and for the time around your sounding.
Radar presentation. Nexrad radar discussion, and what's under the dome video.
Use this archived radar data tool, or this if the first link doesn't work, and obtain data in and around the time of your sounding, as a screen shot if needed.
Optional though recommended:
Detailed instructions for obtaining radar data.
Obtain the Level II (choose radar elevation that works best) or Level III radar composite imagery from the NOAA Weather and Climate Toolkit described in G, to make a movie of the radar data.
For level III data, after choosing your time, the Google served data needs to be unpacked into a folder, and loaded.
Here are a 3 hour animation, and a 24 hr animation obtained for the Reno 3 July 2021 0z case study, showing an outflow boundary, from the lowest elevation scan.
Making the radar movie:
Here's where you choose the radar using COD Radar. Click on "Radar Selection" and it will bring up a map of the NEXRAD sights in continental US. Find the one closest to your sounding location (or weather event) and hover over it to get the abbreviated name and location that will be needed in the Weather and Climate Toolbox.
Find the coordinates of your radar for locations in the continental US (for Alaska, Hawaii, etc you'll need to estimate the coordinates).
G. Use the NOAA Weather and Climate Toolkit to get an infrared image for the time of your sounding to use in identifying cold cloud tops associated with convection.
We will likely use GOES 16 data for coverage of the entire continental U.S., and for better time coverage.
Detailed instructions for obtaining GOES data.
Here's an example of a query. And here is an example image.
The data is "Clean" Infrared Longwave Window Band. The center wavelength for this band is 10.3 microns, or a wavenumber=970.9 cm-1. (wavenumber=1/wavelength).
Estimate cloud top temperature for any convection in the area assuming cloud top is a blackbody radiator.
You can hover over locations of interest and read the infrared radiance.
The measured cloud top radiance can be used with the wavenumber in this calculator to get the brightness temperature.
Also create an GIF or mp4 animation of the location for several hours around the time of the sounding. Tutorial on making animations.
Presentation:
Introduction:
Discuss CAPE and precipitable water vapor amount in the introduction.
Be sure to define each variable when using equations.
Section 1. Use Google Earth and the latitude and longitude coordinates of your sounding to create a map of the location in wide enough of an area to give an idea of its climatological context.
You may find useful climate information on your site here. Describe what motivated you to choose your site.
Section 2. Present your skewT graph and its interpretation, including discussion of the wind speed and direction as a function of height; temperature, and dewpoint temperature; and the lifted air parcel. (See step A).
Section 3. Give a table of values for your location and include:
a. Equivalent potential temperature θE for the averaged air parcel for the first 200 meters of the sounding, the starting point of the lifted air parcel from the surface. This value is constant for the entire trajectory of the air parcel lifted from the surface. It can be read from the sounding as the reported θE averaged over the first 200 meters of the sounding height.
b.
Lifting condensation level height and pressure.
c. Level of free convection in meters and pressure value for it.
d. Tropopause height in meters and the pressure value for it.
e. Equilibrium level height and pressure.
f. Your CAPE value in Joules/kg.
g. Your calculated vertical velocity, w, in meters/second and mph at the equilibrium level based on use of your CAPE value. The equation is w = (2 * CAPE)1/2.
h. Your precipitable water amount in mm units.
i. 500 mb wind direction from the sounding and inferred from the 500 mb level graph.
j. Convective condensation level pressure.
k. Convective temperature.
| Quantity | Units | Comment | How to get it from the skewT diagram. |
| CCL Pressure | mb |
Pressure at the convective condensation level (CCL) | The CCL is the level at which condensation will occur if sufficient afternoon heating causes rising parcels of air to reach saturation. The CCL is greater than or equal in height (lower or equal pressure level) than the LCL. The CCL is found by following the saturation mixing ratio line through the surface dewpoint up until it intersects the environmental temperature curve. Adapted from here. |
| Convective Temperature |
C | Surface temperature the air needs to reach to form clouds by thermal convection caused solely by surface heating | Follow the dry abiabat from the CCL back to the surface pressure level. Read the temperature. Note: This temperature is especially useful for studying pyrocumulonimbus formation associated with forest fires. |
Section 4. Graph with all the potential temperature and equivalent potential temperature curves versus height.
Discuss atmospheric stability using these graphs. (See step D).
Section 5. Prepare a 500 mb level graph and discuss it. (See step E).
Section 6. Obtain the radar still image and animation for several hours after your area, and discuss them. (See step F).
Section 7. Obtain the infrared satellite still image and animation for several hours after your area, and discuss them. (See step G).
Conclusion: Summarize your findings.
Appendix:
a.
You may include any related atmospheric data (like maps of other pressure levels, etc) that helps tell your story.
b. OPTIONAL: Using the sounding text, calculate the CAPE in units of Joules/kg, the estimated vertical velocity at the equilibrium level in meters/second and compare with the value on the sounding.
Also, calculate the precipitable water vapor amount in units of mm and compare with the values given on the sounding.
This spreadsheet will help you calculate temperature along the moist adiabat and gives an example for CAPE and precipitable water calculation.
Replace the example sounding with your own and redo the calculations.
(Here's another version; it also has the calculation of the moist adiabatic lapse rate.) I can assist if you would like to work with the program.
You can also make your own program with any language you would like to do this calculation.
Explain what program you use, and include it in the report.
Tools and Extras
1. Soundings from the University of Wyoming site.
2. You may also obtain archived data for the 500 mb level, and precipitation data from radar imagery here.
3. Historical weather may be obtained here, mostly from surface stations at airports.
3.5 Historical surface analysis showing highs and lows and fronts are available (scroll down).
4. Archived satellite imagery from around the world can be obtained here.
5.
Read section 8.3.1a on Deep Convection, pg 344-371 of Wallace and Hobbs for getting a better understanding of severe storms.
6. Skew T plots discussion.
7. Archived weather radar.
7.5 Severe storms 101 discussion from the National Severe Storms Lab.
7.6 Newscast discussing severe storms and tornados.
8. Ingredients for a thunderstorm and severe weather.
9. Radar discussion.
10. Thunderstorms.
11. The 500 mb pressure chart.
12. Satellite imagery interpretation in brief.
13. Tornado formation discussion.
14. This assignment primarily has concentrated on CAPE.
Dynamical meteorology has a strong effect on severe storm outcomes. Here's an introduction.
Further discussions are in the MetEd modules on Principles of Convection 2: Using Hodographs and Principles of Convection 3: Shear and Convective Storms.
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Resources and Explanations for the NOAA ToolKit
Change the theme in the upper right corner to get something more useful, like streets.
Level 1 data for channel 13: ABI-L2-CTPF is the infrared radiance arriving at the satellite.
Definition of the level 2 derived data types in the toolkit.
ABI-L2-CTPF is the cloud top pressure.
ABI-L2-ACHAF if the cloud top height.
ABI-L2-ACHTF is the cloud top temperature.
Resources for GOES Satellite Imagery on GOES (Geostationary Operational Environmental Satellites):
Overview of how it works. Shorter version.
More details on the satellite instruments.
GOES west real time IR imagery at 10.35 um, converted to brightness temperature. Close look at California and Nevada. Imagery from GOES east.
Optional Severe Weather Software: Python program and executables for viewing observed and modeled soundings in the context of severe weather description.
Journal Articles
Soundings associated with supercell storms.
Effect of entrainment on CAPE.
Evolution of Convective Energy and Inhibition before Instances of Large CAPE 2023. (Backtrajectory analysis used to look at origin of air masses).
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Homework 3. Chapter 3, part 1.
Turn in this homework assignment through webCampus, prepared using Microsoft Word.
Purpose:
Emphasize
understanding of the physical quantities used to describe atmospheric thermodynamics.
Relate atmospheric thermodynamics to hurricane dynamics as a real world application.
Practice using the skewT graph for atmospheric thermodynamics.
Make one MSword document that has solutions for problems 1 through 4.
Read chapter 3.
1. Define and discuss the following quantities (in your own words. Read about them from various sources and then from understanding, discuss them).
Description of how to obtain these temperatures on a skew-T diagram may be useful also.
a. Tv virtual temperature
b. Tdew dew point temperature
c. Tw wet bulb temperature
d.
Tc convective temperature
e. θ potential temperature
f. θw wetbulb potential temperature
g. θE equivalent potential temperature
2. Explain in words (no diagram needed) how to use Normand's rule to obtain the following:
a. Dewpoint temperature from the temperature, pressure, and wetbulb temperature.
b. Wetbulb temperature from the temperature, pressure, and dewpoint temperature.
3. Given these values typical for class room air:
Ambient temperature To=21.3 C, wet bulb temperature Tw=12 C and ambient pressure Po=871 mb.
Deliverables:
a. Skew T diagram showing how Normand's rule, etc, to obtain
the quantities listed below, and values entered into the table.
You can copy and paste this table into Microsoft Word and fill it in. You can delete the "Procedure using skewT" column.
Include your skewT diagram showing how you obtained the various quantities as well.
| Quantity | Units | Value from skewT | Value from Python | Comment | Procedure using skewT |
| Tdew | C | dewpoint temperature | Use Normand's rule | ||
| ws(Tdew) | g/kg | water vapor mixing ratio at saturation at the dewpoint temperature | Read from the skewT | ||
| ws(Tw) | g/kg | water vapor mixing ratio at saturation at the wetbulb temperature | Read from the skewT | ||
| ws(T) | g/kg | water vapor mixing ratio at saturation at the air temperature | Read from the skewT | ||
| RH | % | Relative humidity | RH=ws(Tdew)/ws(T) | ||
| θ | K | n/a | Potential Temperature | Follow the dry adiabat through T down to P=1000 mb and read the temperature. | |
| θw | K | n/a | Wetbulb Potential Temperature | Follow the moist adiabat throughTw down to 1000 mb and read the temperature. It can also be read in the upper level of the skewT we use for class. | |
| θE | K | n/a | Equivalent Potential Temperature | Use Normand's rule to get to the LCL. Then follow the moist adiabat to the top of the atmosphere. Return to 1000 mb along a dry adiabat and read the temperature. It can also be read in the upper level of the skewT we use for class. | |
| LCL Temperature | C | n/a | Temperature at the lifting condensation level (LCL) | Use Normand's rule | |
| LCL Pressure | mb | n/a | Pressure at the LCL | Use Normand's rule |
b.
Obtain the dewpoint temperature from this Python program by entering the values of Po, To, and Tw and put it in the table where noted.
The program can be copied and pasted into this online python interpreter, or this one, or your own version.
You can check the calculation using the National Weather Service water vapor calculator.
The theory for this problem is here, if you want to review it.
4. This problem explores hurricane dynamics and thermodynamics.
It will be in short report format as discussed in Homework 2, this time with references. We will discuss the use of EndNote Online for managing references.
At the center of a hurricane is a warm core low pressure region, the eye of the hurricane.
This table gives a categorization of hurricanes by maximum wind speed range. (local backup).
Deliverables:
a. Discuss the
life cycle of hurricanes: formation, energy source, and dissipation (be sure to cite your references, see Resources.) (include inline references to the literature you cite/use). Discuss especially why the eye of the hurricane is mostly clear of clouds, and why the surface wind in the eye wall is so strong.
b. Create a 'hurricane' table with headings Category, Sustained Wind Range (m/s), Eye Pressure Range (mb), Average Eye Temperature Difference (C).
We will use cyclostrophic flow theory in class to show that the pressure difference between the eye and the surroundings is ΔP=1.81ρv2 where ρ is surface density and v is maximum hurricane wind speed. The pressure at the eye of the hurricane is Peye=Po- ΔP. Be sure to convert the units of ΔP to mb.
Use the eye and surrounding pressure to assumed to be 1010 mb to obtain the average temperature difference between the atmospheric column above the eye and surroundings (see prob 3.26).
[We showed that ΔT=Toln(Po/Peye)/ln(Peye/200mb) where To=-3 C = 270 K, and Po=1010 mb.]
Here's an example of the table for the first entry. It's convenient to use Excel for the table.
Resources:
Section 8.4 pgs 366-371 of the class textbook, .
Hurricane Freddy, Southern Hemisphere 2023, longest lived and most energetic in history.
This paper discusses hurricane properties.
This paper discusses the dynamics of a specific hurricane in detail, including the effect of temperature on hurricane strength.
You can reference it in your report, comparing your values with those in the paper, and find other references for hurricanes using the Web of Science.
We will discuss in class how to use cloud applications for EndNote and WebOfScience to manage references within Microsoft Word (download and install the Endnote plugin for Word).
We did problem 3.26 in class to develop theory for the average column temperature difference and the hurricane eye pressure given the wind speed.
National Hurricane Center site and data.
Numerous websites talk about the circulation in hurricanes.
Hurricane Ian discussion on Tuesday, on Wednesday and on Thursday, September 27-29, 2022.
The powerpoint presentation for chapter 3 may be useful. The hurricane problem is there.
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Homework 2. Chapter 1.
Turn in this homework assignment through webCampus, prepared using Microsoft Word.
Make one MSword document that has solutions for problems 1 through 4.
Purpose:
Study the introductory chapter for an overview of the field.
Access and interpret sounding and reanalysis meteorological data from around the world.
Calculate and graph meteorological variables to investigate their vertical distribution in the atmosphere.
Learn how to make and interpret publication quality graphs for meteorology.
Advance science writing skills.
Learn to calculate integrated vapor transport that's needed for quantifying Atmospheric Rivers. Another description.
Learn to use a solar radiation simulation application for any time and location.
Read chapter 1.
1. Do problem 1.6 parts a, c, d, and i from the textbook. Write your answers into the first part of the MSword document you will be turning in for this assignment.
2. Do problem 1.12 from the textbook, being sure to express your answer in degree C per kilometer.
Then go to the South Pole and find a sounding that best resembles the features of this problem.
Soundings from the South Pole are at Amundsen-Scott station 89009 in Antarctica.
Look at data from perhaps June through August of this year and find a day with cold surface conditions and a strong inversion calculated from the first two points.
You can put the station number 89009 in the website and press enter to access this data.
3. We will go through this problem together in class, step by step. It may be helpful to sit next to someone and work together.
Be sure to ask if you have questions as we go along. You can bring your own laptop, or use the room computers and save your results to a USB drive, or Google Drive, or
Nevada Box, or OneDrive, etc. Be sure to stay caught up as we progress. The requirement is to obtain the data and interpret it.
Prepare a short report that describes the atmosphere for 12Z, 31 January 2024 for these two locations, Rochambeau French Guiana (SOCA, Station 81405) and Barrow Alaska USA (PABR, Station 70026) using the high spatial resolution sounding data.
a. Use Google Earth to view these two locations, Rochambeau French Guiana (coordinates 4.8222, -52.3653) and Barrow Alaska USA (coordinates 71.2889, -156.7833). Save images of each location and use as figures 1 and 2 in your report.
Include grid lines in these images so you can see the Tropic of Cancer and the Arctic Circle, respectively, and discuss the significance of these geographical demarcations, both in of themselves and with respect to the amount of solar radiation expected to be seen seasonally in their vicinity.
b. Acquire the png format skew T soundings for PABR and SOCA for this day and time. Make these soundings figures 3 and 4 in your report.
Discuss these soundings. What is the local standard time at each site for the soundings?
Observe the lapse rate Γ=-dT/dz from the slope of the temperature versus height graph and interpret, along with other feature observed.
c. Near equator: Rochambeau French Guiana (get sounding text for SOCA from the Wyoming site.)
Plot pressure and temperature vs height in km as figure 5 in your report, with pressure on the lower x axis, and temperature on the upper one.
Calculate density and plot versus height in km as a separate graph as figure 6.
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d. Near north pole: Barrow Alaska (PABR).
Get the sounding data for PABR from the Wyoming site.
Overlay pressure and temperature vs height in km with the SOCA pressure and temperature in figure 5.
Calculate density and overlay with the SOCA density in figure 6.
Additionally for ATMS 611 student and extra credit for ATMS 411 students: i. Interpolate the pressure measurements from SOCA and PABR to a common height grid and calculate the 5 times the pressure difference = 5*(PABR - SOCA) as a function of height. The pressure difference values should be negative. Add this calculation to figure 5. Discuss the following questions. Interpolated data is here to use or compare with your calculation. ii. How does the maximum in the magnitude |PABR-SOCA| relate to the PABR temperature profile? iii. What is the dynamical significance of the maximum with regard to large scale circulation in the atmosphere? iv. What might be the consequence of rapid warming in the Arctic on the large scale circulation? |
e. Calculate and graph the water vapor density in grams/m3 for Barrow and overlay with the SOCA water vapor density, as an overlay with figure 6.
Note that water vapor density is the product of density_of_dry_air * w.
Discuss.
f. Then make a graph and fit a trendline for the natural logarithm of pressure, ln(Pressure) vs height
to obtain the scale height of the atmosphere at these two locations,
considering data to a height of 2 km.
Include this graph
as figure 7.
Make a table that has the following quantities in it.
Calculate the scale height
of the atmosphere from the negative reciprocal of the slope.
Use the scale height to calculate the mean virtual temperature of the layer to 2 km.
Calculate the mean virtual temperature of the layer to 2 km also from the sounding.
Compare and discuss these measures of mean virtual temperature.
Here's an example of scale height discussion.
g. Atmospheric river (AR) related analysis. Transport of water vapor.
Note: To understand the total mass transported by an atmospheric river requires more than 1 isolated balloon sounding. This problem is to aid in understanding the primary quantity needed for the first step, quantifying the transport of water vapor by the wind in a column of the atmosphere.
Calculate the vector Integrated Vapor Transport (IVT) (units of Kg/(m s)) and total precipitable water vapor (PWV) (units of mm) for both Barrow and SOCA.
Here is a summary of the relationships needed, repeated in this table.
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The average velocity vector for water vapor transport is equal to the IVT/IWV, where IWV=total integrated water vapor.
The purpose is
to become familiar with this important concept used to described Atmospheric Rivers.
Here are some notes in OneNote format, and in PDF format.
This research paper describes IVT in Eqs. (1) - (5).
This site describes wind as a vector and its speed and direction.
This site describes operational forecast for atmospheric rivers, and water vapor transport analysis.
h. Use this solar position and irradiance calculator (from the National Renewable Energy Lab) to simulate the top of the atmosphere solar irradiance for a detector placed flat on the ground (horizontal detector) every 30 minutes for Jan1 - Dec31, 2024, for SOCA and PABR.
It
also known as the "Extraterrestrial Global Horizontal Solar Irradiance (W/m2)". We will use the acronym EGHSI for it.
The results will be a time series of top of atmosphere irradiance values that need to be brought into Excel and plotted. The x-axis will be the day of the year calculated by first combining time and date into a new column, and then using the formula given here.
Make these figures 8a and 8b, on one page for ease of comparison. Discuss these figures.
This image shows the setup for getting numbers for SOCA (change latitude and longitude to get PABR numbers), and this image show which field to use for the irradiance (the temperature and pressure don't matter in the first part).
The Earth's orbital path around the sun is elliptical rather than circular. Note that the solar zenith angle, which is the complement of the solar elevation angle, affects EGHSI more than variation of the Earth-Sun distance as discussed here. This simulation is useful for understanding the Earth's tilt and its effects on seasons, in addition to the variation of irradiance due to the Earth-sun distance. Zooming in the SOCA data to an irradiance range from 1200 to 1400 Watts/m2 shows both the effect of solar zenith angle and the asymmetry for the yearly maximum due to the time of the peak and minimum Earth-sun distance as compared with the time of the solstices.
In summary for this problem:
In your report, compare and contrast the difference in the meteorology between these two sites
as a function of height in the atmosphere, both near the surface and throughout the atmosphere.
NOTE: A short report should be written like a short section in a text book.
A. Title for the report. Your name. If you want you can add your future professional position you would like to have.
B. The first paragraph(s) describes what's in the report, describes what is to be accomplished. References to other literature should be in the name year format, e.g. Smith et. al. 2020. We will discuss using EndNote to manage references.
C. Each figure must have a number and a caption. Figures must be in publication format -- high quality figures with 18 point (or greater) bold black font; tick marks inside. All axes 1 point thick and black.
D. Each figure must be discussed in the text by number, describing the significance of the figure and its relationship to other figures as needed.
E. Any equations should be offset, as in a textbook, and each equation should have a number. Refer to equations by number.
Use the equation editor in microsoft word to prepare your equations.
F. The last paragraph should summarize the overall outcome of the report, and possibly discuss your results in comparison with literature results as in part B.
Get started early.
G. List of cited references.
Take advantage of the UNR writing center to have them read your report draft to give you feedback on writing quality.
TOOLS:
A. Meteorological data can be obtained from the University of Wyoming web site.
B. Most (or all) computers readily accessible to all students, using their netID, have Google Earth, MSword, and Excel.
C. Students can download office for their home computer. Excel and Word are available for students and faculty here. Sign in with your UNR netID and download Office to your computer. We will import data using the text wizard: Excel:File:Options, then check this box.
D. Description of balloon soundings of the atmosphere.
E. References to published papers and websites can be easily managed with EndNote. Scroll down to "Manage your references" for instructions.
F.This Python script can be used to plot the balloon trajectories in Google Earth, by creating a .kml file that can be read directly into Google Earth.
Use the "Output Data : Comma Separated Values" to get the data from the high resolution sounding page. (Not required but useful).
4. a. Do problem 1.21 from the textbook. This is similar to problem 1.20 from the textbook we will do in class. Show that the air speed is v=(dp⁄dt) RE ⁄ Ps where RE is Earth's radius and Ps is the average surface pressure. Calculate the air speed and use units of mm/second.
b. Here are graphs of the surface pressure averaged from 1950 - 2019 for Dec/Jan/Feb and for June/July/August.
Discuss the seasonal variation of surface pressure in the Northern hemisphere in summer and winter, locations of highs and lows, and meteorological consequences.
This is discussed an online dynamics textbook near Figure 2.3, the pertinent section is here.
[This data is from NCEP/NCAR. One objective of this problem is to become aware of this data].
[Data from NOAA, Physical Science Laboratory, Monthly/Seasonal Climate Composites]. Historical data is available in another form here.
c. Here is a time series image for this problem, obtained with a web-tool, and this spreadsheet has the details.
Web-based tool for time series development of atmospheric quantities, and intercomparison of reanalysis products.
Does the pressure distribution support the likely increase of pressure in the Northern Hemisphere?
Resources for problem 4:
Reanalysis Summary.
Summary of typical available reanalysis sources.
Homework 1.
Turn in this homework assignment through webCampus, using Microsoft Word, etc.
Skew T lnP Practice homework based on the atmosphere of 17 August 2024 at 12Z chosen at random:
Reno sounding location is 72489 REV (39.56, -119.8). Slidell Louisiana sounding location is 72233 LIX (30.34, -89.83).
Instructions: Place your results from parts 1 through 7 into a Microsoft Word or PDF Document and submit it to Webcampus
You can use OneNote or other programs for doing the homework, just export the assignment as a PDF document.
Download the blank skewT graph with curves marked, or a blank skewT graph to Microsoft Paint, or your favorite image program.
1. From the Reno morning sounding text, make a table with the temperature and dewpoint temperature for pressures of mb of 850, 700, 500, 400, and 250 mb. If data is missing at a level, choose the closest value (Local backup).
2. Put these points on the blank skewT graph using Paint, save your skewT image file.
3. Obtain the actual sounding for the morning, circle the temperature and dewpoint temperature values at the pressures given in part 1. (Local backup).
Compare with your skewT from part 2 with the actual sounding in part 3 to make sure you are understanding these charts.
4. Download the Slidell Louisiana 12Z sounding and discuss the comparison with the Reno sounding.
5.
Make a Google Earth map using the coordinates for each location to help your discussion of the meteorology you would expect for Reno and Slidell.
Google Earth can be downloaded as an application for your device, or used from the web.
6. What are the local daylight savings and local standard times in Reno and Slidell at the time these soundings?
7. Obtain the approximate 11:30 a.m. local time NASA Worldview (MODIS Image) and use it to help interpret the meteorological differences.
Resources
Some skewT lnP applications and measurements.
Skew T lnP MetEd Module that covers nearly everything, starting with the basics.
How to convert to and from UTC.
Upper air soundings and skewT discussion.
This Python script can be used to plot the balloon trajectories in Google Earth, by creating a .kml file that can be read directly into Google Earth.
Use the "Output Data : Comma Separated Values" to get the data from the high resolution sounding page. Not required but useful.
Time zone in Reno.
World time zone map and Greenwich England.
Current time UTC (Coordinated Universal Time).
World time converter.
Video describing skewT diagrams.
Example of radiosonde errors that can lead to faulty skewT diagrams.
FINAL PROJECT, START NOW!
Deliverables:
ATMS 411 in class presentation and turn in presentation in through WebCampus.
ATMS 611 in class presentation, report, and turn in through WebCampus.
Presentations need to be between 5 to 20 minutes long.
Take photographs and/or use other data for the atmosphere, and/or investigate a specific topic we haven't covered in class, or covered lightly (such as the ionosphere, or lightning) and explain the Atmospheric Physics connection. The project topic is not limited to obtaining cloud pictures and explaining them, but can be within the rather broad umbrella of Atmospheric Physics. Please check with me if you have questions or want to talk about resources for the project.
For observational projects, as an example, you can use more than one photograph or data source, and can look at a variety of phenomena.
For example, blue sky, sky polarization, coronas, halos, rainbows, lenticular clouds, gravity waves, lightning, water phase clouds, ice phase clouds,
inferring air motions and winds from cloud structures, contrails, vortices in contrails, sky color during pollution events, sky color near the horizon, sky color at sunset looking to the east.
Photographs of the dendritic nature of ice growing on windshields on cold days, the shape and nature of icicles, dew on a moist mornings are also possible topics.
Photographs of snow flakes and snow crystals, here's a discussion.
If you have special hobbies or work, like paragliding, Atmospheric Physics related
aspects can be included in your project.
You can use soundings, satellite images, weather station data, etc, to also help tell the story.
ATMS 411 students will do a presentation. Presentation hints. 7 secrets of great speakers. Teachable moments.
ATMS 611 students will do a presentation and a report. Report format.
Due Dates:
Presentations: Presentations begin on Wednesday the week before prep day. Prep day is on a Wednesday too. Turn in your presentation through webCampus by Tuesday night.
Reports for 611 students: The Sunday after prep day. They can be submitted as a second file through webCampus.
Resources that may help
Gravity wave discussion.
Snow crystal/flake observations.
Cloud identification.
NASA WorldView for satellite imagery. You can add layers for additional information.
National Weather Service balloon soundings, served by the Univ of Wyoming.
Weather station data from the Western Regional Climate Center at DRI. In particular, the UNR weather station.