Layers of the Atmosphere
Week 19-Earth Science
Exploring the Atmosphere
Layers of the Atmosphere
Layers of the Atmosphere
What is the atmosphere?
What is the atmosphere?
By the end of today
The Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Ionosphere
By the end of today
Ozone
Ozone
“The ozone hole opened the world’s eyes to the global effects of human activity on the atmosphere. Scientists found out that chlorofluorocarbons (CFCs)—long-lived chemicals that had been used in refrigerators and aerosol sprays since the 1930s—had a dark side. In the layer of the atmosphere closest to Earth (the troposphere), CFCs circulated for decades without degrading or reacting with other chemicals. When they reached the stratosphere, however, their behavior changed. In the upper stratosphere, ultraviolet light caused CFCs to break apart, releasing chlorine, a very reactive atom that repeatedly catalyzes ozone destruction.
The global recognition of the destructive potential of CFCs led to the 1987 Montreal Protocol, a treaty phasing out the production of ozone-depleting chemicals. Scientists estimate that about 80 percent of the chlorine (and bromine, which has a similar ozone-depleting effect) in the stratosphere over Antarctica today comes from human, not natural, sources.”
2006
2019
Recovery
“Scientists have already seen the first definitive proof of ozone recovery, observing a 20 percent decrease in ozone depletion during the winter months from 2005 to 2016.
Models predict that the Antarctic ozone layer will mostly recover by 2040”
Measured in Dobson units (DU)
Thus, the total ozone would be 0.3 atm-cm.
The “Dobson Unit” is defined to be 0.001 atm-cm. Our 0.3 atm-cm would be 300 DU.
What are ozone mini-holes?
During what months do the highest values of ozone occur over the Antarctic?
During what months do the lowest values of ozone occur over the Antarctic?
How long does the ozone hole typically last?
What’s it doing right now?
Estimate the range of Dobson units over the Antarctic pole.
Estimate the range of Dobson units over the rest of the map excluding the Antarctic pole.
Surface Ozone
So, what is ozone?
Free chlorine atoms react with ozone molecules, taking one oxygen atom to form chlorine monoxide and leaving an ordinary oxygen molecule.
When a chlorine monoxide molecule bumps into a free atom of oxygen, the oxygen atom breaks up the chlorine monoxide, stealing the oxygen atom and releasing the chlorine atom back into the stratosphere to destroy more ozone.
Some Questions…
Heat Domes and Ozone Pollution
Why study heat domes and their effects?
Heat and air pollution might be two of the biggest threats to our planet as the climate changes. The term “heat dome” is heard in the summer, when unusually high temperatures occur. A significant event can last a few days, or a few weeks. The biggest challenges come when a heat dome occurs in a location where exceptionally high temperatures is an unusual weather pattern. Temperature records may be broken. The effects on living things and infrastructure can be severe.
Researchers have found that the risk of death surges when extreme heat and air pollution coincide.
Credit: CDC
Warm, sunny skies increase the concentration of ozone over cities. Heat domes create especially hazardous conditions in harmful levels of pollution. A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap.
High-pressure circulation in the atmosphere acts like a dome or cap, trapping heat at the surface and favoring the formation of a heat wave. (What is a heat dome? (noaa.gov))
GOES satellite data and ground-level sensors were used to create models showing the extent of a June 2021 heat dome, with effects as far north as Alaska.
June 27, 2021 Exceptional Heat Hits Pacific Northwest (nasa.gov)
The heat dome occurred over the Pacific Northwest and British Columbia in June 2021. Temperatures in some locations were more than 15 degrees Fahrenheit above normal, for nine days. While the heat was intense in one location, below-normal temperatures occurred elsewhere, like Texas. (If the video does not play, use this link Heat Wave Surface Temperature (nasa.gov)
Question Set 1
1. Which states were most affected by the heat dome?
2. What other area, even larger, was most affected by the heat dome?
3. Describe something you know about these areas that made this heat dome particularly devastating.
How does ozone form?
Ground-level 'bad' ozone forms when nitrogen oxide gases from vehicle and industrial emissions react with volatile organic compounds -- carbon-containing chemicals that evaporate easily into the air, such as gasoline and paint thinners. Ozone data have been collected from space by NASA's Total Ozone Mapping Spectrometer (TOMS) aboard several satellites that flew between 1978 and 2005 and now from the Ozone Monitoring Instrument (OMI) on the Aura satellite, launched in 2004.(NASA - Increasing 'Bad' Ozone Threatens Human and Plant Health)
False-color view of total ozone over the Antarctic pole. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone. https://ozonewatch.gsfc.nasa.gov/
Don’t confuse stratospheric ozone with surface ozone!
NASA eClips: Review of stratospheric ozone
UCAR: Review of surface ozone
4. What is the difference between stratospheric and surface ozone?
Surface ozone forms when the necessary ingredient pollutants are present, often from sources such as vehicles. With more vehicles in a large city, there is more potential for ozone to form during warm, sunny days. Is there evidence for an increase in ozone during the heat dome in the Pacific Northwest in 2021? Use this slide and the next slide to compare the data from Portland, Oregon.
5. What, if any, similarities in the data do you see between the two graphs? (Answer on this slide or the next slide.)
5. What, if any, similarities in the data do you see between the two graphs? (Answer on this slide or the previous slide.)
5. What, if any, similarities in the data do you see between the two graphs? (Answer on this slide or the previous slide.)
6. Identify the highest values on both graphs. Are these data points on the same date?
7. Are the dates during the Pacific Northwest heat dome?
8. Is this enough data to prove that the high ozone readings were caused by the excessively high temperatures? Why or why not?
9. While this may or may not be enough evidence to conclusively know if there is a connection between temperature and ozone, what would make this evidence stronger?
10. Look at the data for July 28-29. The ozone readings are high, but the temperatures are not as high as in June. Propose an explanation for why the ozone readings could still be high even when the temperatures aren’t.
11. What evidence would you need to prove your explanation?
Want to find out more?
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