3/14/2016. Chapter 17

Transcription

1 Chapter 17 Layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly 78% nitrogen, 21% oxygen, and 1% other. Its four layers differ in temperature, density and composition Human activity is changing the amounts of some gases Inactive gases 1% Video Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. From highest to lowest, these layers are: 1. Exosphere: atmosphere merges with outerspace (>440 miles) 2. Thermosphere: International Space stationg orbits, aurora borealis (50 to 440 miles) 3. Mesosphere: coldest, meteors burn here (31 to 50 miles) 4. Stratosphere: ozone layer (7 to 31 miles) 5. Troposphere: weather (0 to 7 miles) 1

2 3/14/2016 Weather is a short-term atmospheric condition in an area. They include: Temperature Humidity Precipitation Cloud cover What is the weather today here? Climate is a region s general pattern of atmospheric condition over a long period of time (at at least 30 years). years The two major factors contributing to a region s climate: What is the climate for here? Climate is what we expect; weather is what we get average temperature average precipitation Climate is determined by: Atmospheric Circulation Patterns Oceanic Circulation Patterns Local geography Solar activity Volcanic Activity Which is most important? Latitude (How far above/below you are from the equator) Video Mark Twain REASON FOR SEASONS Latitude is the distance north or south of the equator. Measured in degrees. Equator is 0 degrees, the poles are 90 degrees Low Latitudes get the strongest, most concentrated sunlight. Night and Day are 12 hours, all year round High temps all year round High Latitudes sunlight is spread over a greater area, weaker, less energy Daylight hours vary At the poles the sun sets for only a few hours during the summer Dark almost all day during winter Average annual temperatures lower than at equator. Three basic rules: 1. Cold air sinks but pressure is stronger at lower levels so cold air gets compressed and thus warms. 2. Warm Air Rises lower pressure lets it expand and it cools down 3. Warm Air holds more water vapor than cold air so as it rises the water vapor cools and condenses How do we get wind? 1. Sun heats the earth surface. 2. Hot Air Rises 3.Cold Air replaces it wind! 2

3 CORIOLIS EFFECT Coriolis effect = the north-south air currents of the convective cells appear to be deflected from a straight path Results in curving global wind patterns Because the Coriolis effect increases with an item s increasing speed, it significantly deflects airflows and as a result the wind. In the Northern Hemisphere these winds spiral to the right and in the Southern Hemisphere they spiral to the left. This usually creates the westerly winds moving from the subtropical areas to the poles. Ferrel cells and polar cells = lift air Creates precipitation at 60 degrees latitude north and south Causes air to descend at 30 degrees latitude Hadley Cells are the low-latitude overturning circulations that have air rising at the equator and air sinking at roughly 30 latitude. They are responsible for the trade winds. A lot of rain. Planetary Winds Global scale winds are winds that are created in the different Global circulation Cells. The polar easterlies blow from the Pole to 60 The Prevailing Westerlies blow from 60 to 30 Near the equator The Trade Winds blow from 30 to 0 Video Current Animation GPS video OCEAN CIRCULATION PATTERNS The Gulf Stream is driven largely by wind, but as it branches into the North Atlantic Drift, it is largely thermohaline circulation driven. Ocean currents Currents also help mix ocean waters to distribute nutrients and dissolved oxygen needed for aquatic organisms Winds moving away from coastal regions result in upwelling of cold, nutrient-rich bottom waters as surface water moves offshore. These nutrients support large populations of phytoplankton, zooplankton, fish, and fish-eating sea birds. El Niño and La Niña are changes in climate patterns that can trigger mild to extreme weather changes over at least ⅔ of the globe. Video 3

4 ENSO El Niño/Southern Oscillation (ENSO) results from a change in direction of tropical winds. Trade winds blowing west are weakened or reversed. Surface water warms along the North and South American coasts, and upwelling of nutrients is suppressed, which reduces primary productivity that results in sharp decline of fish population. Jet stream above North America is also distorted, changing weather patterns. leads to increased clouds and rainfall in SW US La Nina La Niña cools some coastal surface waters and brings back coastal upwelling. This results in warmer, drier winters in the southeastern and southwestern U.S., wetter winters in the Northwest. Typically a La Niña causes more destruction in the U.S. because there are more Atlantic coast hurricanes and tornadoes. Similar to normal conditions, just enhanced. Simulation El Niño Animation RAIN SHADOW Rain Shadow Dry area on the eastern side of mountains The smaller the mountains, the weaker the rain shadow effect, and vice versa. Temperature Inversion Air circulation usually stops pollution from accumulating to dangerous levels. Inversions trap pollution near the Earth s Surface Temperature usually decreases with altitude But a warm layer above a cold layer will trap pollution (Hot air rises, right? Hot smoke rises, but if atmosphere is just as warm, the smoke stays put) Video 4

5 Volcanoes Lightning Forest fires Plants Air pollution Sources Natural Sources of Air Pollution Anthropogenic Sources of Air Pollution On-road vehicles Power plants Industrial processes Waste disposal Air Pollution chemicals, particulate matter, or microorganisms found in the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings or to alter ecosystems Primary pollutants: polluting compounds coming directly out of smoke-stacks, exhaust pipes, or natural emission source Five types: CO, CO 2, SO 2, NO x, and most suspended particulate matter Secondary pollutants: pollutants transformed in the presence of sunlight, water, oxygen or other compounds Examples: ozone, sulfate, and nitrate What is the biggest source of primary pollutants? Transportation 5

6 AKA: Tropospheric Ozone Ground Level Ozone is formed when car emissions (primary) interact with oxygen and UV rays (both natural) Major factors are H 2 O and Sunlight Pollutant Composition Source P/S Effects Particulate matter Nitrogen oxides Sulfur oxides Carbon oxides Major Air Pollutants Various Industry P Respiratory illness NO 2 SO 2 CO, CO 2 Cars, industry, fertilizer Coal-fire power plants Cars, industry P P P Irritate respiratory Irritate respiratory Reduces blood s ability to carry O 2 ozone O 3 Photochemical S Irritate eyes, respiratory Particulate Matter Particulate Matter (PM)-is a complex mixture of extremely small particles and liquid droplets Ex: organic chemicals, metals, and soil or dust particles. EPA is concerned about particles that are 10 micrometers (PM 10 ) or lower. Go into your lungs and bloodstream. Lead-(Pb) is a metal found naturally in the environment as well as in manufactured products. Major sources are from fuels in on-road motor vehicles (such as cars and trucks) and industrial sources. Also in paint, dust and soil Neurological effects in children and cardiovascular effects 6

7 Industrial plants burn fossil fuels Burning releases Sulfur Dioxide and Nitrous Oxide Power Plants emit 2/3 of ALL SO2 and 1/3 of ALL NO VOCs (Volatile Organic Compounds) - chemical compounds that form toxic fumes Given off by Oil refineries, Dry Cleaners, Chemical plants VOCs Industrial Air Pollution Plant Scherer Georgia Smog: forms when sunlight, nitrogen oxides (Nox), and volatile organic compounds (VOCs) are present. Industrial (gray air) smog = industries burn coal or oil Photochemical smog (brown air) A secondary pollution Photochemical smog is still an environmental problem in the United States. Sunlight + Nitrogen Oxides + VOCs produced Ozone. Secondary Pollution Video Clip (smog eating building) Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 7

8 Photochemical Smog Industrial smog Sulfur dioxides (SO 2 ) Photochemical smog Nitrogen Oxide (NO) Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings OZONE LAYER Ozone is the chemical compound O 3 Large concentration is found in the stratosphere Ozone Layer absorbs most UV radiation coming from the sun UV radiation can damage organisms cells UV-B- most absorbed by ozone Chemicals Can Destroy Ozone CFCs chlorofluorocarbons CFCs used as propellants in spray cans and coolants in fridges/air conditioners It takes years for CFCs to reach the stratosphere from the Earth's surface CFCs are broken apart in the stratosphere High energy of the UV radiation breaks it down The single chlorine from CFC can react with O 3 and changes it, depleting the O 3 Scientists estimate that a single chlorine atom can break down 100,000 ozone molecules. OZONE LAYER Ozone depletion 8

9 First noticed in 1970 from satellite photos over the South Pole What Causes it? During the cold polar winters, dry stratospheric air over the pole is isolated. Air becomes so cold that it condenses and forms clouds (Polar Stratospheric clouds: high-altitude clouds made of water and nitric acid at - 80 C) Chlorine from CFCs builds up on the surface of the clouds When the pole begins to warm the chlorine goes back to depleting ozone. VIDEO ON OZONE DEPLETION OZONE LAYER OZONE LAYER Negative affects of ozone depletion: Ever have a bad sunburn? UV radiation can damage organisms DNA Phytoplankton can be killed by UV The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion. Many nations banned the use of CFCs in 1992 (US stopped production by 2000) CFCs still a problem.why? CFCs molecules remain in the stratosphere for years Acute-short term effects Can be reversed when exposure is decreased Nausea Headaches Eye Irritations Coughing Upper respiratory infections (bronchitis, pneumonia) Greatest effect on children ages 5 and lower Chronic- long term effects Cannot be reversed when exposure is decreased Emphysema Lung Cancer Heart Disease May damage lungs of young children Air inside a building is sometimes WORSE than air outside Chemicals used in making carpets, furniture, copy machines, and paints can pollute indoor air Sick Building Syndrome buildings with very poor air quality Buildings that are sealed have very poor air quality Preventing bad indoor air pollution Remove the source of the pollution Remove carpet, new paint Good ventilation to mix the indoor air with outdoor air Decreases the amount of pollution per unit of air 9

10 3/14/2016 Radon Gas Colorless, odorless gas 2nd leading cause of lung cancer Occurs after uranium decays, found naturally in the earth, can seep into houses. Have a radon detector in the house Defined as unwanted sound Noise kills nerve cells in the ear 12% of teens have permanent hearing loss Intensity of sound is measured in decibels 120 db is at the threshold of pain. Asbestos Not a direct hazard to human health Does impact environment and enjoyment of night sky. Bigger threat is wasted energy Upward directed light is wasted, only goes to space A fire resistant substance used in building materials before the 1970s. When inhaled the fibers can cut and scar the lungs leading to breathing difficulties and heart failure. Billions of dollars have been spent in asbestos removal Acid Deposition Acid deposition: nitrogen oxides and sulfur oxides released into the atmosphere combine with atmospheric oxygen and water. These become the secondary pollutants nitric acid and sulfuric acid. Effects of Acid Deposition Lowers the ph of lake water Acid Shock-mass killing of aquatic organisms Decreases species diversity in aquatic These secondary pollutants further break down into nitrate and ecosystems sulfate, which create the acid in acid deposition. Mobilizes metals (aluminum) found in soils and releases these into surface waters Metals accumulate in fish bodies until reach toxic levels Damages statues, monuments, and buildings and other structures 10

11 Acid rain is hard to regulate because the pollution that causes it blows with the wind. One country s pollution could float into another country causing acid rain there. Countries are signing Air Quality agreements with each other to help reduce polluting emissions Acid rain may dissolve the calcium carbonate found in concrete, marble, and limestone. Ways to Prevent Air Pollution Scrubber Catalytic converters on cars Scrubbers on smoke stacks- : cleans emissions of plants by washing it and filtering it Baghouse filters Electrostatic precipitators - uses static charges to get particulates to clump together and collect, clean gas continues on. (used in cement factories/coal burning plants) 11

12 Clean Air Act Federal law that regulates air emissions. This law authorizes EPA to establish National Ambient Air Quality Standards (NAAQS) to protect public health and the environment. The setting of maximum pollutant standards was coupled with directing the states to develop state implementation plans (SIP's) applicable to appropriate industrial sources in the state. Overseen by Environmental Protection Agency (EPA) The EPA required the gradual elimination of lead in gasoline. To date lead pollution has been reduced by more than 90 % in US. California Zero Emission Law Is that possible? Battery operated vehicles are the only true ZEVs (zero emission vehicles) 12