3.5 Explore What Other Factors Contribute to the Air...

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AIR QUALITY AQ 151 climate: the normal weather conditions of a region, throughout the year, averaged over a series of years. 3.5 Explore What Other Factors Contribute to the Air Quality in Los Angeles? Los Angeles is a large city with about 9 million people. New York City and its surrounding region have about the same size population. Both cities have lots of cars, are seaports, and have airports. But the pollution in Los Angeles is much worse than in New York City. You will look at maps of Los Angeles and New York City to help you identify the geographic factors that are contributing to the poor air quality in Los Angeles. Then you will think about how the climate might affect air quality. Finally, you will observe models showing how the climate and geographic features of Los Angeles contribute to its pollution. Observe Every area in the United States has geographic and geologic features that affect its air quality. If a city is located on the ocean, winds might carry its pollution out to sea. Or, winds blowing in from the sea might carry the pollution in the opposite direction. In flat areas, the wind usually blows pollution away from cities. Mountains might keep polluted air inside an area. Look at the maps on the next page of the Los Angeles area and New York City to see what you can figure out about how the geography of Los Angeles might affect its air quality. 1. Compare the geography that is west of Los Angeles with the geography that is west of New York City. What is the same? What is different? 2. Prevailing winds in the United States generally blow from the west or southwest. With this in mind, compare the geography east of Los Angeles with the geography east of New York City. Where will pollutants go in each case?

Transcript of 3.5 Explore What Other Factors Contribute to the Air...

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climate: the normal weather conditions of a region, throughout the year, averaged over a series of years.

3.5 Explore

What Other Factors Contribute to the Air Quality in Los Angeles?

Los Angeles is a large city with about 9 million people. New York City and its surrounding region have about the same size population. Both cities have lots of cars, are seaports, and have airports. But the pollution in Los Angeles is much worse than in New York City. You will look at maps of Los Angeles and New York City to help you identify the geographic factors that are contributing to the poor air quality in Los Angeles. Then you will think about how the climate might affect air quality. Finally, you will observe models showing how the climate and geographic features of Los Angeles contribute to its pollution.

ObserveEvery area in the United States has geographic and geologic features that affect its air quality. If a city is located on the ocean, winds might carry its pollution out to sea. Or, winds blowing in from the sea might carry the pollution in the opposite direction. In flat areas, the wind usually blows pollution away from cities. Mountains might keep polluted air inside an area.

Look at the maps on the next page of the Los Angeles area and New York City to see what you can figure out about how the geography of Los Angeles might affect its air quality.

1. Compare the geography that is west of Los Angeles with the geography that is west of New York City. What is the same? What is different?

2. Prevailing winds in the United States generally blow from the west or southwest. With this in mind, compare the geography east of Los Angeles with the geography east of New York City. Where will pollutants go in each case?

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Project-Based Inquiry Science

Learning Set 3 • What Are Pollutants, and How Do They Get Into Air?

AQ 152

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The climate of an area can also affect air quality. Many areas in the Western United States receive more sunshine and are drier than areas along the East Coast. In drier areas, the wind may lift more dust particles into the air. In areas with more sunshine, more smog may form from ground-level ozone. Many areas in the south are warmer and more humid than areas in the north. In areas with a lot of rain, the rain may wash some types of pollution out of the air. Look at the charts showing the climate in Los Angeles and New York to see what you can figure out about how the climate of Los Angeles might affect its air quality.

3. Look at the data for average daily temperatures for Los Angeles and New York City. During what time of year do you see the highest temperatures? These are the most likely times for ozone and smog.

Los Angeles, CA Climate Data

Average Temperature

FortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 18.3 13.8 14.4 15 16.6 17.7 19.4 22.2 22.7 22.2 19.4 17.7 15

°F 65 57 58 59 62 64 67 72 73 72 67 64 59

Average High TemperatureFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 22.7 18.3 18.8 20 21.1 22.7 24.4 27.7 27.7 27.2 25 22.7 20

°F 73 65 66 68 70 73 76 82 82 81 77 73 68

Average Low TemperatureFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 12.7 8.8 9.4 10 11.6 13.3 14.4 16.6 17.2 16.1 14.4 11.6 10

°F 55 48 49 50 53 56 58 62 63 61 58 53 50

Average PrecipitationFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

cm 35.6 6.9 7.9 5.6 3.3 0.8 0.3 0 0 0.5 1.0 2.8 6.4

in. 14 2.7 3.1 2.2 1.3 0.3 0.1 0 0 0.2 0.4 1.1 2.5

Average number of days above 32ºC (90ºF)FortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Days 16 0 0 0 1 1 1 3 3 5 3 1 0

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Project-Based Inquiry Science

Learning Set 3 • What Are Pollutants, and How Do They Get Into Air?

AQ 154

New York, NY Climate Data

Average Temperature

FortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 12.7 0 1 6.1 12 17.2 22.2 25 24 20 15 8.8 3

°F 55 32 34 43 53 63 72 77 76 68 58 48 37

Average High TemperatureFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 17.2 3.3 4.4 10 16.1 22.2 26.6 29.4 28.8 24 18.3 12.2 6.1

°F 63 38 40 50 61 72 80 85 84 76 65 54 43

Average Low TemperatureFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

°C 8.3 -3.3 -2.7 1.7 7 12.2 17.2 20.5 19 15.5 10 5 -0.5

°F 47 26 27 35 44 54 63 69 67 60 50 41 31

Average PrecipitationFortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

cm 188.6 8.8 7.9 10.2 9.7 11.2 9.1 11.2 10.4 10.2 8.6 11.2 9.7

in. 46.7 3.5 3.1 4.0 3.8 4.4 3.6 4.4 4.1 4.0 3.4 4.4 3.8

Average Number of Days Above 32ºC (90ºF)FortheYear Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Days 19 0 0 0 0 1 3 8 5 1 0 0 0

What difference do you see in the average daily temperatures of Los Angeles and New York City?

4. Look at the data for average rainfall. You already know that rain cleans the air. How do you think the average rainfall in Los Angeles contributes to its pollution?

ReflectWhy do you think the air in Los Angeles is so much more polluted than the air in New York City? Use your observations to justify your answer. Discuss your answers with the class. Later, you will observe models that will allow you to better understand the answer to this question, and you will have a chance to answer it again.

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Observe Convection,Part1

The air near Los Angeles is much warmer than the air near New York City. The air warms up and stays warm. This warmed air moves in a convectioncurrent.

You will be watching a video of the convection model. The water in the model represents air. Liquid water and gaseous air are both fluids. A fluid is matter that can flow. Even though they are different states of matter, the flow of water can be used to represent the flow of air. As you watch, notice how the warm water moves and how the cold water moves. After you have observed the model two times, you will match the parts of the model to the features around Los Angeles.

Analyze Your Data1. Describe what you saw in the convection

model. On a Convection and Inversion page, sketch what you saw, and label the parts of the model. Indicate the direction in which the water (representing air) moves. Indicate where the warmer water and the cooler water are in the model.

2. What do you think is the source of energy that heats the air in Los Angeles?

3. Imagine that the convection model was Los Angeles in the summer. What happens to the polluted air?

4. What would be different in New York City? Why?

3.5 Explore

convection: the transfer of heat in a fluid through a current made up of warm, rising fluid and cool, sinking fluid.

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Project-Based Inquiry Science

Learning Set 3 • What Are Pollutants, and How Do They Get Into Air?

AQ 156

ObserveConvection,Part2You have seen the process of convection. As the water moves in the model, the warmer water moves to the top. The process of convection happens in the Los Angeles area and has a large impact on the air quality in the area.

Watch the convection video again. This time, the parts of the model in the video are labeled.

Analyze Your Data1. How did the parts in your original sketch compare with the parts labeled

on the second video?

2. Examine your answers to the questions you answered after watching the first video. Answer each question again.

ObserveInversion,Part1The convection process you observed in the earlier video is the air pattern that occurs under normal circumstances. It shows how air moves when it is free to move anywhere. All over the world, convection currents move air from one area to another. In some places, however, geography prevents air from flowing freely. In Los Angeles, mountains tower high over the region to the north, east, and south. These mountains affect how the air can move.

You will now watch a video that models an atmospheric condition called thermalinversion. In an inversion, the position, or arrangement, of

How Does the Convection Video Model the Air in Los Angeles?When air near Earth’s surface is warmed, its particles spread out, and the air rises. The particles of the cooler air above the warm air are packed more tightly together. This air then sinks. As the warm air rises, it cools, while the cool air close to the ground warms. Again, the warm air rises, and the cooler air sinks. The continuous process of rising and sinking air forms a pattern known as a convection current. The process of convection transfers heat through a fluid by the movement of particles.

thermal inversion: a weather condition where an overlaying mass of heated air prevents the circulation of air beneath it, stopping convection.

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something is changed. The video will show you what a thermal inversion is. Thermal inversion is common in Los Angeles. As in the other model, the water in this model represents air. Watch what happens to the warmer water and the cooler water in the model. Remember that this model is similar to Los Angeles. Cool water moves in and bumps against an obstacle. It cannot move freely. Watch what happens to the cool water, and watch what happens to the warm water. You will watch the video two times.

Analyze Your Data1. On a new Convection and Inversion page, sketch the path of the water

that you observed, and label the parts of the model.

2. Compare the water movement in this video to the water movement in the convection video.

3. Imagine that the cool water in this model represents cool air coming in to Los Angeles from the ocean, and the obstacles represent the mountains to the north, east, and south of Los Angeles. How do you think these air movements affect the air quality in Los Angeles?

4. Do you think it would be different in New York City? Why or why not?

ObserveInversion,Part2Watch the video again. This time, the parts of the model are labeled.

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Project-Based Inquiry Science

Learning Set 3 • What Are Pollutants, and How Do They Get Into Air?

AQ 158

Why Do Thermal Inversions Happen?Thermal inversions are common to Los Angeles because of its unique combination of geography, climate, and population. In normal convection, warm air near the ground rises into cooler air higher up. As warm air mixes with cooler air, the pollution breaks up. The rising air helps carry pollutants up and away from the ground.

Analyze Your Data1. How did the parts in your original sketch compare with the parts labeled

on the second video?

2. Examine your answers to the questions you answered after watching the first video. Answer each question again.

Reflect1. Which parts of the inversion model match the geographic features

of the Los Angeles region? For example, which features represent the mountains?

2. Think about the models you observed. If these models are accurate, what happens to the air of Los Angeles as it moves from west to east and bumps into the mountain range?

3. Why do you think the number of sunny days in Los Angeles affects its air pollution?

Convection

cool air

cooler air

warm air

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However, in a thermal inversion, warm air sits on top of cold air and acts like a lid. This is the situation you observed in the second video. When this happens, the warm air and cool air cannot mix, and the pollutants are not broken up and carried away.

In California, cool air from the ocean blows in at ground level during the night, especially in the winter. Normally, when the Sun rises, this air heats up, rises, and convection begins. But when the air above the cool air is warmer than normal, the cool air mass cannot rise. It gets “stuck” against the mountains and might stay there for several days.

Meanwhile, car exhausts continuously emit nitrogen oxides, carbon monoxide, and VOC’s. The longer the thermal inversion lasts, the more pollution builds up in the air. The increased pollutants, combined with heat from the Sun, cause ozone levels to exceed safe health levels. A cloud of smog covers the city. It blocks vision and causes eye irritation and lung distress. During these “smog alert” days, people are cautioned to remain inside as much as possible. Thermal inversions in Los Angeles are serious health hazards, causing lung problems, asthma, and even death for people who are already ill.

ReflectAnswer the following questions with your group. Be prepared to share your answers with the class.

1. Why do you think warm air rises? To answer, use what you know about gases, mass, behavior of molecules, and temperature.

Thermal Inversion

cooler air

cool air

warm inversion layer

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Project-Based Inquiry Science

Learning Set 3 • What Are Pollutants, and How Do They Get Into Air?

AQ 160

2. Geography and frequent thermal inversions cause Los Angeles to have the worst air quality in the United States. What factors cause Los Angeles to have frequent thermal inversions?

3. What do you think a community can do to decrease air pollution during thermal inversions?

4. Do you think your community experiences thermal inversions? Why or why not? If your community does not have thermal inversions, describe the factors in your community that prevent inversions.

ExplainNow that you know about Los Angeles and the factors that affect its air quality, you will explain the causes of its poor air quality. Begin by developing a claim about factors that affect air quality in Los Angeles. Record your claim on a Create Your Explanation page. Use as evidence what you know about the pollutants, and the geography, population, and climate of Los Angeles. Record science knowledge that supports your claim from your experiences. It may also come from readings. Then write a statement that connects your claim to the evidence and science knowledge. This is your explanation. A good explanation statement will describe how the geography, pollutants, and climate of Los Angeles act together to cause Los Angeles’s air pollution.

CommunicateShareYourRevisedExplanationShare your group’s claim and explanation with the class. Tell the class what makes your claim accurate based on your evidence and science knowledge. Pay special attention to how the other groups have supported their claims with science knowledge and to other groups’ explanation statements. Ask questions or make suggestions if you think a group’s claim is not as accurate as it could be, if the group has not supported their claim well enough with evidence and science knowledge, or if you think a group’s explanation statement is not complete or accurate.

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Revise Your ExplanationAs a class, develop a claim and explanation statement that the entire class agrees with. Notice any disagreements class members have. Develop questions for the Project Board that can be answered to settle any disagreements.

Update the Project BoardUse the Project Board to record what you have learned about convection and inversion in the What are we learning? column. Include what you know about thermal inversion and the effect of inversions on air pollution, especially in Los Angeles. Record your evidence in the What is our evidence? column. Add any questions the class has developed to the What do we need to investigate? column.

What’s the Point?The pollution problems in Los Angeles are due to a combination of climate, combustion products, and geography. The large population in Los Angeles results in a large number of cars and other sources of combustion. The cars, in turn, produce nitrogen oxides, carbon monoxide, and VOC’s. The nitrogen oxides and VOC’s, combined with sunlight, lead to the formation of ozone and smog.

The geography of Los Angeles adds to its pollution. Los Angeles has the Pacific Ocean to the west. Mountains surround it on the other three sides. These mountains trap the air, making Los Angeles likely to have thermal inversions, often for several days at a time.

In the normal situation of convection, warm air close to land rises and mixes with colder air in the upper atmosphere. Convection moves pollution away from the land and dilutes it in the upper atmosphere. In thermal inversion, warm air sits on top of colder air, holding it in place. Pollutants stay trapped in the colder air, close to the ground. The mountains east of Los Angeles keep the cold air from escaping out from under the “lid” of warm air.