Week 16: 6 December
No class on Wednesday.
Continue with final project presentations.
Take home final to be assigned on Thursday December 9th.
We will meet in class on Thursday from 9:50 am to 11:50 a.m. for final presentations as needed and discussion.
As time permits:
Cloud physics discussion.
Related Information:
Homogeneous formation of cloud droplets theory (local backup).
Week 15: 29 November
Presentations for the final project begin on Wednesday December 1st.
Tuesday and week in summary
Effect of ground surface reflection on the reflectivity (albedo) of a cloud. (Multiple scattering between cloud and ground).
Notes for this problem (right click, save, and open with OneNote)..
Optical depth for clouds that makes for the brightest clouds.
Chapter 4: Radiation transfer (presentation).
Take solar radiation from the top of the atmosphere to the surface, showing effects of gaseous and aerosol absorption and scattering on the spectra See slides 27- 32.
Global radiation balance and deficit See slides 12, 26.
How radiation absorption couples with atmospheric thermodynamics and layer heating.
Layer heating rate = -divergence of net irradiance (also known as flux). Slides 39, 41, 42.
Begin cloud physics chapters 5 and 6 presentation.
Wednesday
Presentations for final projects begin.
Thursday
Presentations for final projects continue.
Friday
Presentations for final projects continue as needed.
Related Information:
Short presentation on black carbon aerosol.
Week 14: 22 November
Presentations for the final project begin on Wednesday December 1st.
Tuesday and week in summary
Bring questions about homework 6 to class.
Discuss use of the Mie theory calculator.
Summary of scattering regimes and rainbows. Rainbow phase function. Notes (right click, save, and open with OneNote).
Weather radar and the Rayleigh regime. Notes (right click, save, and open with OneNote).
Wednesday
In class demonstration of multiple scattering and diffraction.
Effect of ground surface reflection on the reflectivity (albedo) of a cloud. (Multiple scattering between cloud and ground).
Optical depth for clouds that makes for the brightest clouds.
Chapter 4: Radiation transfer (presentation).
Short presentation on black carbon aerosol.
Take solar radiation from the top of the atmosphere to the surface, showing effects of gaseous and aerosol absorption and scattering on the spectra See slides 27- 32.
Global radiation balance and deficit See slides 12, 26.
How radiation absorption couples with atmospheric thermodynamics and layer heating.
Layer heating rate = -divergence of net irradiance (also known as flux). Slides 39, 41, 42.
Begin cloud physics chapters 5 and 6 presentation.
Related Information:
Real and imaginary parts of the refractive index of water (and spreadsheet with values.)
Electromagnetic penetration depth compared with typical hydrometeor diameter.
Theory of multiple scattering in one dimension (an excellent research and teaching paper).
Multiple scattering theory with and without light absorption.
Week 13: 15 November
Tuesday and week in summary
Theory for homework 6 developed.
Chapter 4: Radiation transfer (presentation).
Radiative budget at the Earth's surface and the greenhouse effect. Model development and in-class homework assignment.
Wednesday
Continue discussing the 1-layer atmosphere model, and absorption of solar radiation by black carbon aerosol. See the updated notes from Tuesday, we will continue from there.
Notes (right click, save, and open with OneNote).
Thursday
Zoom issues today: Here's the zoom recording link, and the actual zoom recording for the class. (Reach out if you have problems).
The recording should be available from the zoom link in webCampus. If you missed class be sure to watch this recording.
Refractive index of water and ice as a function of wavelength. Electromagnetic penetration depth relationship.
Light scattering and absorption by aerosols and cloud hydrometeors:
Use the size parameter to find the scattering regime (characteristic behavior for different wavelength and particle diameters).
Notes (right click, save, and open with OneNote).
Friday
Scattering, absorption, and extinction efficiency factor, Qsca.
Optical depth for a cloud having N cloud droplets per unit volume and cloud height L.
Asymmetry parameter g to use for determining the fraction of radiation scattered forward and backwards.
Radiation reflected and transmitted by clouds in the multiple scattering regime, including clouds above the ground.
Theory of multiple scattering in one dimension (an excellent research and teaching paper).
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).
Infrared radiative transfer in the atmosphere through a layer of water vapor and carbon dioxide.
Related Information:
Real and imaginary parts of the refractive index of water (and spreadsheet with values.)
Electromagnetic penetration depth compared with typical hydrometeor diameter.
Theory of multiple scattering in one dimension (an excellent research and teaching paper).
Week 12: 8 November
Tuesday and week in summary
Theory for homework 5 developed, due on Friday.
Homework 5 has been assigned. Start right away on it. We'll go over it in class. Read chapter 4.
Problem 4.21, effect of Earth-sun distance and Earth albedo changes on the astronomical temperature of the Earth.
Chapter 4: Radiation transfer (presentation).
Basic relationships for black body radiation (radiation with a certain spectral distribution). (Planck).
Wednesday
Problem 4.29, what is the response time of the Earth to sudden changes such a volcanic emissions? (Atmosphere and ocean).
Notes from class.
Thursday
No class due to holiday.
Friday
Discuss student answers for problems 4.21 and 4.29.
Continue to discuss polarization of sky light and the color in the context of Rayleigh scattering.
See slides 77-81 and 95-97.
Go outside at the end of class to observe optical properties of the sky.
Discuss the last homework problem on IR from the tropics and polar regions and the Earth's radiation budget.
Upcoming:
Radiative budget at the Earth's surface and the greenhouse effect. Model development and in-class homework assignment.
Light scattering and absorption by aerosols and cloud hydrometeors: Use the size parameter to find the scattering regime (characteristic behavior for different wavelength and particle diameters).
Radiation reflected and transmitted by clouds in the multiple scattering regime, including clouds above the ground.
Infrared radiative transfer in the atmosphere through a layer of water vapor and carbon dioxide.
Related Information:
Spectrum of sunlight at the surface and the response of the human eye as a function of wavelength.
Brief discussion of human vision.
Real and imaginary parts of the refractive index of water (and spreadsheet with values.)
Electromagnetic penetration depth compared with typical hydrometeor diameter.
Variation of the Earth-sun distance over the year due to the elliptical orbit.
The Dixie fire created its own weather.
Week 11: 1 November
Tuesday and week in summary
Last presentations for Homework 4 on Tuesday, Zoom and in class.
Take home midterm exam due Monday night.
Chapter 3 on the theory of atmospheric thermodynamics.
Sound propagation in the atmosphere and the role of the lapse rate. (see presentation for equation of sound speed).
Sonic anemometer measurement of wind speed and direction, three coordinates.
Wednesday
Visit the UNR weather station and view the downwelling solar and IR radiation for the last week.
Thursday
Homework 5 has been assigned. Start right away on it. We'll go over it in class. Read chapter 4.
Chapter 4: Radiation transfer (presentation).
Basic relationships for black body radiation (radiation with a certain spectral distribution). (Planck).
Friday
Short wave and long wave radiation
Astronomical energy balance: Sun and Earth.
Energy balance at the surface.
Blue sky, white clouds, radar, aerosol.
Reminder of final project,
Preparation:
Read chapter 4: Radiation transfer.
Related Information:
Meteorology club visitor on Thursday at 1:30 p.m.
Spectrum of sunlight at the surface and the response of the human eye as a function of wavelength.
Brief discussion of human vision.
Meteorological model soundings and vertical cross sections.
Real and imaginary parts of the refractive index of water (and spreadsheet with values.)
Electromagnetic penetration depth compared with typical hydrometeor diameter.
Variation of the Earth-sun distance over the year due to the elliptical orbit.
Week 10: 25 October
Tuesday and week in summary
Presentations for Homework 4 begin on Tuesday.
We will have both in class and zoom presentations.
Take home midterm exam Thursday through Monday.
Chapter 3 on the theory of atmospheric thermodynamics.
Waves in the atmosphere: Gravity waves and sound waves.
Chapter 4: Radiation transfer (presentation).
Basic relationships for black body radiation (radiation with a certain spectral distribution). (Planck).
Short wave and long wave radiation
Astronomical energy balance: Sun and Earth. Shortwave and longwave radiation.
Energy balance at the surface.
Blue sky, white clouds, radar, aerosol.
Visit the UNR weather station and view the downwelling solar and IR radiation for the last week.
Reminder of final project,
Preparation:
Practice your presentation.
Do the take home exam.
Read chapter 4: Radiation transfer.
Related Information:
Brief description of our atmospheric river event bringing rain and snow to the Sierras. (National Weather Service).
Surface emissivity and hygroscopicity and dew formation.
Week 9: 18 October
Tuesday and week in summary
Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read homework problem 4. You'll need to choose a sounding for this assignment.
Read the section of chapter 8 on convection referred to in Homework 4.
Read chapter 3, Atmospheric Thermodynamics.
Review the problem we did last Friday, problem 3.48 on flow over mountain ranges.
Topics
Obtain thetaE for the problem 3.48 that we worked on last Friday. Bring your skewT to class.
Discuss thetaE using OneNote.
Use the simple relation for thetaE to discuss it below and above the LCL,
and for a 100% efficient precip process to the TOA, and back down dry.
Discuss why thetaE is important. (Map of thetaE). (Map of CAPE).
Stability of the atmosphere.
Wednesday
Make the graph of theta and thetaE versus height for your sounding, part D of homework 4.
Conditional and convective instability of the atmosphere.
Precipitable water.
Convective available potential energy (CAPE).
Thursday
Make sure you have your sounding chosen for assignment 4. We'll be using it in class to gather the related data for this assignment.
Talk about the assignment. Color the skewT. Get the reanalysis 500 mb map of the location with +- 20 degrees N/S and W/E of the sounding location.
Friday
Obtain the radar data and the IR satellite imagery for our case studies on assignment 4.
Bring questions to class about your sounding.
We likely will have presentations start next week, Tuesday.
Latent heat release and the moist adiabatic lapse rate.
Waves in the atmosphere: Gravity waves and sound waves.
Related Information:
CAPE assignment 4 example: Reno 3July2021 0Z sounding and local backup.
Get the archived radar data for it.
Get the archived GOES 17 clean IR from the NOAA Weather and Climate Toolkit.
Issues and errors with soundings.
SkewT discussion for education.
Week 8: 11 October
Tuesday and week in summary
Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read homework problem 4. You'll need to choose a sounding for this assignment.
Read the section of chapter 8 on convection referred to in Homework 4.
Read chapter 3, Atmospheric Thermodynamics.
Topics
Derivation of the dry adiabatic lapse rate.
Discuss homework 4 on CAPE and stability of the atmosphere.
Note: The sounding date you find must be on or after 3/1/2017 so that GOES satellite imagery is available.
I will be using the Reno 3July2021 0Z
sounding for an example, so this one is not available for use.
Wednesday
Potential temperature derivation.
Significance of the potential temperature.
Latent heat and the saturated adiabatic lapse rate.
Thursday
NASA Worldview may help when looking for a day with convection (true color images at around 1:30 pm local time).
(Soundings from the Univ of Wyoming).
Latent heat and the saturated adiabatic lapse rate.
Friday
Problem 3.49 and flow rain shadow effect. Chinook wind.
Stability of the atmosphere.
Conditional and convective instability of the atmosphere.
Precipitable water
Convective available potential energy
Latent heat release and the moist adiabatic lapse rate
Waves in the atmosphere: Gravity waves and sound waves
Related Information:
CAPE assignment 4 example: Reno 3July2021 0Z sounding and local backup.
Get the archived radar data for it.
Get the archived GOES 17 clean IR from the NOAA Weather and Climate Toolkit.
Poisson, person of many equations, including PVγ=constant for an adiabatic process, eventually leading to the equation for potential temperature. γ=cp/cv.
Weather balloon launch in calm air (Reno NWS office).
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Week 7: 4 October
Tuesday and week in summary
Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read chapter 3, Atmospheric Thermodynamics.
Online homework 3 due.
Homework 3 due.
Endnote and Web Of Science cloud applications for managing and finding published research.
Make an account for each, and install the plugin for Microsoft Word.
Wednesday
Discuss homework problem 4 on hurricane dynamics.
Thursday
Endnote and Web Of Science cloud applications for managing and finding published research.
Part of the UNR library.
Make an account for each, and install the plugin for Microsoft Word.
Friday
UNR Atmospheric Science in the news.
Reduction of pressure to sea level.
Altimeter for getting elevation from pressure measurements.
Types of thermodynamic processes.
First law of thermodynamics
Specific heat capacity of air for constant pressure and volume processes.
Equipartion theorem and heat capacity.
Derivation of the dry adiabatic lapse rate.
Potential temperature derivation.
Significance of the potential temperature.
Discuss homework 4 on CAPE and stability of the atmosphere.
Latent heat and the saturated adiabatic lapse rate.
Problem 3.49 and flow rain shadow effect.
Stability of the atmosphere.
Conditional and convective instability of the atmosphere.
Related Information:
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Physics Nobel Prize in 2021: Complex Systems Including Climate.
Here is a paper by Manabe that looks at climate modeling.
Here is an earlier paper on the subject that also points out complexity.
Here is an update of the Manabe 1975 paper.
UNR Office of Undergrad Research.
CAPE assignment example: Reno 3July2021 0Z sounding and local backup.
Get the archived radar data for it.
Get the archived GOES 17 clean IR from the NOAA Weather and Climate Toolkit.
Week 6: 27 September
Tuesday and week in summary
Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read chapter 3, Atmospheric Thermodynamics.
Read problem 3 and work on the first problem as you read the chapter.
Continue discussing homework problems 2 and 3.
Water vapor mixing ratio on skewT diagrams (labeled version, unlabeled version)
Normand's rule
Wednesday
Discussed potential temperature and its uses.
Hydrostatic equation.
Variation of g with altitude.
Thursday
Geopotential.
Thickess of atmospheric layers.
Friday
Intro to height contours and wind direction (oneNote).
Geostrophic wind calculation from the gradient of geopotential height.
Hurricane problem discussion, problem 4 of homework.
You're invited: The Ongoing CA/NV Drought: A PanelDiscussion. 3 pm, DMS auditorium.
From: https://www.weather.gov/jetstream/
Related Information:
Constant pressure surfaces versus constant elevation surfaces.
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Week 5: 20 September
Tuesday and week in summary
Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read chapter 3, Atmospheric Thermodynamics.
Read problem 3 and work on the first problem as you read the chapter.
Chapter 3 topics
We will have several homework assignments from this especially important chapter.
The goals (learning and review objectives)
a. Ideal gas equation applied to dry and moist air.
b. Virtual temperature.
c. Potential temperature.
d. Hydrostatic equation.
e. Increasingly detailed description of the temperature and pressure distribution in the atmosphere.
f. SkewT logP diagrams.
f-g. Relative humidity, absolute humidity.
g. Dew point temperature.
h. Wet bulb temperature.
i. Equivalent potential temperature.
j. Latent heat release and absorption in condensation and evaporation of water.
k. Stability of air parcels.
l. Indices on soundings.
m. Brunt–Väisälä frequency and gravity waves.
o. Sound propagation in the atmosphere.
p. Hurricane thermodynamics and dynamics.
Wednesday
Water vapor discussion continued.
Saturation vapor pressure over ice and water at the same temperature.
Supersaturation and mixed phase clouds.
Aircraft icing discussion (deicing fluids include antifreeze, ethylene glycol).
Kinetic theory of pressure, relation to molecular speed and average kinetic energy PV=⅔KE.
Water vapor gas constant. And the ratio of water vapor to dry air molecular mass, ε=0.622.
Thursday
Discussed project tools and Reno's minimum air temperature in summer over time. (first 3 subjects)
Virtual temperature.
Water vapor mixing ratio.
Friday
In-class lab day.
Measure temperature, wet bulb temperature, and pressure and get properties of the atmosphere.
Homework problem 3 discussion.
Water vapor mixing ratio on skewT diagrams (labeled version, unlabeled version)
Normand's rule
Hydrostatic equation.
Variation of g with altitude.
Geopotential.
Thickess of atmospheric layers.
Hurricane problem discussion, problem 4 of homework.
Related Information:
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Week 4: 13 September
Tuesday and week in summary
Make progress on homework assignment 2 over the weekend.
Bring questions to class.
Cloud storage for documents should be available through Google drive, if you don't already have cloud storage.
Discuss problem 1.6d in the homework, the distribution of water vapor and ozone in the atmosphere compared with N2, O2, and CO2
and can refer to the plots of pressure and temperature as a function of altitude.
Vertical structure of the atmosphere.
Calculate, graph, and discuss density, and water vapor density as a function of altitude.
Wednesday
Obtain the scale height of the first 2 km of the atmosphere from a trendline for a plot of ln(Pressure) vs height. See homework for theory.
Thursday
Review the scale height of the atmosphere determination.
Calculate the average temperature of the 0 km to 2 km layer from the scale height, and compare with the measured average virtual temperature.
Discuss this as a means of checking the measurement accuracy for temperature and pressure, and of the relationship between them.
Answer any questions about homework 2.
Discuss slides 25 and 30, western US and global precipitation and circulation that gives rise to them.
Friday
Discuss homework 3
We will start Chapter 3 on the theory of atmospheric thermodynamics.
Preparation:
Read chapter 3, Atmospheric Thermodynamics.
Chapter 3 topics
We will have several homework assignments from this especially important chapter.
The goals (learning and review objectives)
a. Ideal gas equation applied to dry and moist air.
b. Virtual temperature.
c. Potential temperature.
d. Hydrostatic equation.
e. Increasingly detailed description of the temperature and pressure distribution in the atmosphere.
f. SkewT logP diagrams.
f-g. Relative humidity, absolute humidity.
g. Dew point temperature.
h. Wet bulb temperature.
i. Equivalent potential temperature.
j. Latent heat release and absorption in condensation and evaporation of water.
k. Stability of air parcels.
l. Indices on soundings.
m. Brunt–Väisälä frequency and gravity waves.
o. Sound propagation in the atmosphere.
p. Hurricane thermodynamics and dynamics.
Related Information:
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 18Z model |
 12Z sounding |
Week 3: 6 September
Tuesday and week in summary
Be sure to do online homework 2.
Preparation: Read chapter 1 and read over homework assignment 2, especially problems 3 and 4.
Students should complete questions 1 and 2 in the homework by Tuesday before class.
Install Google Earth (free) and Microsoft Office (Excel, etc, free when you login using your netID) on your home computer.
We will use them for problem 3 (and others later).
Review problem 1.20 that we worked on last Friday.
Calculate the mass flux carried by the trade-winds, and the time for the entire atmosphere mass to pass through the tradewinds.
Discuss problem 4 in the homework associated with the seasonal variation in surface pressure in each hemisphere.
Wednesday
Discuss global surface pressure in summer and winter seasons for problem 4 in the homework.
Discuss how these data are obtained.
Problem 3 Comparison of meteorology near the equator and near the north pole.
Use Google Earth to scope the two sampling locations, Rochambeau French Guiana and Barrow Alaska.
Acquire the PNG soundings for this locations. Add them also to the MSword document.
Discuss how to caption figures in MSword and how to cross reference to them in the text.
Thursday
Discussed the Reno balloon Races as a current event in Atmospheric Physics, and application of Archimedes principle.
Calculated density and buoyancy for the balloon.
Discuss the structure of the report. Figures, captions, and text that describes what the figures show (discuss in class).
Import the sounding data into Excel. Graphed pressure, temperature as a function of height.
Your spreadsheet should be to this point.
Friday
Start class by answering all questions about how to work with the data.
Be sure everyone is caught up and knows how to import sounding data and graph it.
Double check to make sure everyone is able to save their calculations.
Calculate, graph, and discuss density, and water vapor density as a function of altitude.
Emphasize development of publication quality graphics.
Be ready to go when class starts.
(Investigate the OneDrive issue by trying out this site. https://onedrive.live.com and logging in using NetID.)
Discuss slides 25 and 30, western US and global precipitation and circulation that gives rise to them.
We will start Chapter 3 on the theory of atmospheric thermodynamics after Chapter 1.
Related Information:
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Week 2: 30 August
Tuesday and week in summary
Be sure to do online homework 1.
Preparation: Read chapter 1 and read over homework assignment 2.
Bring questions about homework 1 to class, concerning the skewT lnP thermodynamic diagrams of the atmosphere.
Revisit briefly the exponential model for pressure discussion and scale height for possible changes in the jet stream as polar regions warm.
Answer a question about vertical motions in the atmosphere.
Tuesday
Cyclostrophic flow and hurricane wind speed from centrifugal and pressure gradient balance. Devastation due to hurricane Ida.
Composition of the atmosphere presentation, and temperature variation. (ppt)
Discuss the variation of CO2 with time and the likely consequences.
Wednesday
Start Discussion of Homework 2
Hurricane dynamics, simple model for winds.
Lapse rate discussion in general for problem 2.
Reno summer time morning and afternoon soundings discussed.
Thursday
Review sounding indices from Tuesday.
View the atmospheric boundary layer for 8/25/2021, and vertical motions (from the UNR doppler lidar in Physics, Dr. Lareau).
Discussed PM2.5 measurements on top of the Physics building and inside of it and noted the response time of the building.
Problem 1.12 Antarctica lapse rate discussion (see homework 2).
Friday
Review problem 4 Seasonal variation in surface pressure in each hemisphere.
Related example problem: Problem 1.20 Flow associated with trade winds near the equator and set up of homework problem 1.21. Slide 26 of presentation.
Satellite imagery showing the IR imagery for the tropical eastern pacific.
Earth School animation of the NOAA Global Forecast System (GFS) model output to view the intertropical convergence zone (ITCZ) and trade winds.
Discuss homework 2 problem 1.21 on seasonal pressure changes in the northern hemisphere.
Problem 3 Comparison of meteorology near the equator and near the north pole.
Login to your account with Excel, using your netID, to the computers in the classroom or at home, before class so you're ready to go when class starts.
(Students in class will need to first logout of Excel and log back in so that saving to your OneDrive works properly).
Related Information:
Vertical distribution of aerosol and vertical motions of the air above the Physics building example from lidar for 8/25/2021.
Vertical structure of the atmosphere.
It's hurricane season! Image and animation of the Eastern Pacific. Images from this very useful weather website.
Hurricane track.
Hurricane formation discussion.
Week 1: 23 August
Friday
SkewT lnP thermodynamic diagrams of the atmosphere and homework 1 set up in class.
Thursday
Exponential model for pressure variation with height, and relationship for scale height. Cold and warm air meet on the polar front; jet stream.
Composition of the atmosphere presentation, and temperature variation.
SkewT lnP thermodynamic diagrams of the atmosphere and homework 1 set up in class.
Wednesday
Discussed practical aspects of density and typical values, and mirages. (Thanks for the question).
Pressure and mass of the entire atmosphere calculated with the Python tool. Prepare by setting up an account.
Pressure in the ocean.
Exponential model for pressure variation with height, and relationship for scale height. Cold and warm air meet on the polar front; jet stream.
Composition of the atmosphere presentation, and temperature variation.
Tuesday
Introductions and pressure discussion using OneNote.
| Introductions -- each student introduce themselves. |
| Syllabus. |
| Homework. |
| Webcampus for online homework assignments/reading. |
How to monitor smoke conditions, ATMS example Geostationary satellite loop for the western US Smoke Pollution Measurements at UNR |
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Online Homework 1 is due 30 Aug 2021. See webcampus. This is based on MetEd. Online Homework 2 is due 6 Sept 2021. See webcampus. This is based on MetEd. Homework 1 is due 27 August, to be turned in through web campus. Homework 2 is due 13 Sept, to be turned in through web campus. |
The final project has been posted. |
Additional homework for this week: Read chapter 1.
This class is:
One part lecture;
One part active class participation/activity involving atmospheric data from around the world;
One part study using online modules for atmospheric science education.
Start with a discussion of atmospheric pressure.
Mass of the atmosphere calculation using an online Python editor.
Overview Presentation: Atmospheric Science relies heavily on measurements and models!
Vertical structure of the atmosphere.
Related Information:
It's hurricane season! Image and animation of the Eastern Pacific. Images from this very useful weather website.
Hurricane track.
Hurricane formation discussion.
It's fire season too! Loyalton fire tornado!
Satellite imagery for 19 August 2020.
Satellite imagery for 20 August 2020 with IR detection of hotspots (NASA polar orbiting satellite).
Animated satellite imagery for 20 August 2020 from GOES 16 (NOAA geostationary satellite).
Fire and meteorology feedback: Air pollution in Reno on the 16th of August. Meteorology on the 15th and 16th of August. Note the difference in stability and boundary layer height.
World record hail stone in Vivian South Dakota. See more on hail.
Wind barbs. Click image for larger version.
Reminder of cause for the seasons.
The fountain in Pittsburgh PA and its rainbow.
