Troposphere -atmospheres inner layer -contains most of Earths air -N 2 ( 78% ), O 2 ( 21% ), CO 2 ( 0.04% ) -weather occurs here -temperature drops with an increase in altitude
Stratosphere -layer above troposphere -temperature rises with altitude -our global sunscreen
Stratosphere contd -contains O 3good ozone -ozone layer prevents 99% of harmful ultraviolet radiation from reaching Earths surface
Ozone in the Troposphere (Pollutant) Trace amounts of O 3 that form in the troposphere as a component of urban smog cause damage to: plants materials, e.g., rubber respiratory systems of humans & other animals
What is Air Pollution? -one or more chemicals in high enough concentrations in the air to: 1)harm organisms or materials 2)alter climate -these chemicals are called air pollutants.
Sources of Air Pollution 1.Natural events (e.g., volcanic eruptions, dust storms) 2.Human activities (e.g., emissions from cars and smoke stacks)
Major Air Pollutants 1.Carbon Dioxide (CO 2 ) linked to global warming 2.Sulfur Dioxide (SO 2 ) Linked to global warming, acid deposition 3.Nitrogen Oxides Linked to global warming
Major Classes of Air Pollutants contd 4.Volatile Organic Compounds - e.g., methane, propane, benzene, chlorofluorocarbons (CFCs) found in paints and protective coatings have long-term health risks including: compromised immune system in infants respiratory disorders
Major Classes of Air Pollutants contd 5.Suspended Particles - e.g., solid particles (dust, asbestos, soot) - e.g., liquid droplets (pesticides, sulfuric acid) - linked to respiratory disorders
Types of Air Pollutants Primary Pollutant - chemical, that occurs in a harmful concentration, added directly to the air by natural events or human activities e.g. sulphur dioxide, carbon monoxide, carbon dioxide
Types of Air Pollutants contd Secondary Pollutant - harmful chemical formed in atmosphere when a primary air pollutant reacts with the normal air components or with other air pollutants e.g. ozone, sulphur trioxide
Urban Air Pollution Smog - originally a combination of smoke & fog - now describes other mixtures in the atmosphere
Urban Air Pollution contd Industrial Smog - consists mainly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid and a variety of suspended solid particles - found in cities that burn large amounts of coal and heavy oil which contain sulfur impurities
Effects of Climate & Topography on Air Pollution Areas with high average annual precipitation, help cleanse the air of pollutants. Winds help sweep pollutants away and bring in fresh air. Hills & mountains reduce the flow of air in valleys below and allow pollutant levels to build up at ground level.
Effects of Climate & Topography on Air Pollution contd Buildings in cities slow wind speed & reduce dilution and removal of pollutants. The process of hot air rising and cold air sinking causing continual mixing of air, helps keep pollutants from reaching dangerous levels near the ground.
Temperature Inversion -also called thermal inversion -a layer of warm air settles over a layer of cooler air that lies near the ground. -the warm air holds down the cool air and prevents pollutants from rising and scattering allowing them to build up to harmful levels
Smoke rising in Lochcarron, Scotland is stopped by an overlying layer of warmer air – thermal inversion
Acid Deposition -the falling of acids and acid-forming compounds from the atmosphere to the earths surface -commonly known as acid rain
Acid Rain -refers only to wet deposition of droplets of acids and acid-forming compounds - natural precipitation is slightly acidic (pH 5.0- 5.6) - acid rain can have a pH of 4.3 or 3 (as acidic as vinegar)
Harmful Effects of Acid Deposition -contributes to human respiratory diseases -damages foliage and weaken trees -contaminate fish -damages statues, buildings, metals, & car finishes -releases aluminium ions which damage tree roots
Greenhouse Effect -natural effect that traps heat in the troposphere -some of the heat flowing back toward space from Earths surface is absorbed, by H 2 O vapour, CO 2, O 3 and other gases, then radiated back toward Earths surface
Greenhouse Gases -gases in the troposphere that cause the greenhouse effect -include: carbon dioxide chlorofluorocarbons (CFCs) ozone methane water vapour nitrous oxide
Greenhouse Gases contd -the 2 predominant greenhouse gases are: -water vapour -carbon dioxide -if the atmospheric concentrations of these gases increase, the average temperature of the troposphere will gradually rise
Global Warming -warming of atmosphere due to increases in the concentrations of one or more greenhouse gases primarily as a result of human activities, mainly: burning of fossil fuels use of CFCs agriculture deforestation
Global Warming contd In recent decades certain greenhouse gases have increased in concentration: carbon dioxide methane nitrous oxide CFCs CO 2 contributes to ~ 55% of global warming.
Possible Impacts of Global Warming on Caribbean States -disastrous for ecosystems e.g. coral reefs (coral bleaching) -alter climatic conditions faster than some species could adapt -shift food-growing areas -rise in sea levels due to melting of icecaps and glaciers may flood coastal settlements
Meltwater from Ice Sheet in Greenland flowing into ocean http://www.sciencedaily.com/releases/2009/06/090612092741.htm
Possible Impacts of Global Warming on Caribbean States contd -more frequent and fierce hurricanes -disastrous for economic and social systems
Ozone Layer -layer of gaseous ozone that protects life on Earth by filtering out harmful ultraviolet radiation from the sun -being depleted by CFCs, halons and other chemicals
CFCs -Chlorofluorocarbons -used in air conditioners, refrigerators, aerosol spray cans, cleaners for electronic parts, hospital sterilants, fumigants, plastic foam -ozone eaters
Impact of Ozone Depletion -increased cases of cancer & cataracts -suppression of human immune system -lowers crop yield -degradation of materials -reduction in phytoplankton
Noise Pollution - any unwanted, disturbing or harmful sound that impairs or interferes with hearing, causes stress, hampers concentration and work efficiency or causes accidents
Solutions to Air & Noise Pollution -enforce air & noise pollution laws -use emission control devices -ban or limit smoking to well-ventilated areas -tax each unit of pollution produced -use office machines in well-ventilated areas -shift to less polluting energy sources -increase intake of outdoor air -car exhaust inspections