2 13-1 Climate and Climate Change Objectives1. Explain the difference between weather and climate.2. Identify four factors that determine climate.3. Explain why different parts of the earth have different climates.4. Explain what causes the seasons.
3 What Factors determine climate? Climate-long term prevailing weather (state of the atmosphere)Determined by:Latitude, atmospheric conditions, circulation patterns, oceanic patterns, local geography, solar activity, and volcanic activity.
4 LatitudeAmount of solar energy that reaches the surface
5 Atmospheric circulation Warm air rises, cold air sinksWarm air holds more moistureHeat differences cause winds
6 Global Circulation Patterns Patterns are disrupted at the equatorCool air rises at the equator and is forced to the polesAir condenses and 30 degrees N and SAir sinks, causes water to evaporate from landFlows back to the poles or equator
7 Prevailing winds (westerlies) Blow from one direction most of the yearTrade winds at 30 degrees N and S
8 Ocean Circulation patterns Hold vast amounts of heatCurrents redistribute heatCold and warm currents
9 El Nino – Southern Oscillation Short-term periodic change in the location of warm and cold currents in the Pacific oceanWinds in west Pacific become stronger and push warm water eastwardCauses drought in Indonesia and Australia
10 Pacific Decadal oscillation La Nina -Water in the Pacific is colder than usualPacific Decadal oscillationLong term change in currents
13 Solar activityIncrease UV and energy from the sun
14 Volcanic activityReleases gases (SO2)and dust into the atmosphere which affects weather
15 13-2 Ozone Shield Objectives 1. Explain how the ozone layer shields the Earth from much of the sun’s harmful radiation.2. Explain how chlorofluorocarbons damage the ozone layer.3. Explain the process by which the ozone hole forms.4. Describe the damaging effects of ultraviolet radiation.5. Explain why the threat to the ozone layer is still continuing today.
16 Ozone layer – ozone is concentrated Ozone ShieldOzone layer – ozone is concentratedO3Absorbs UV – protects DNA of all living things
17 Chemicals that cause Ozone depletion CFC’s (chlorofluorocarbons) damages ozoneStable at surface but reacts in atmospheredestroys ozone molecules
18 Ozone hole Thinning of atmospheric ozone that occurs at the poles First report in 1985, but noticed in 1970’s
19 Chlorine reacts with ozone and destroys it Form in polar stratospheric cloudsCan’t be replaced by ground level ozone
20 AffectsIncreased UV radiationDamages DNACancerWeaker immune system
21 Kills phytoplanktonHarms amphibians, marine life, and plants
22 International agreements (Montreal Protocol) to eliminate CFC use Protection of OzoneInternational agreements (Montreal Protocol) to eliminate CFC useUS pledged to ban all substances by 200Did we do it??Level is going down
23 It will be years before affects of programs can be measured because CFCs stay active for years
24 13-3 Global Warming Objectives 1. Explain why Earth’s atmosphere is like the glass in a greenhouse.2. Explain why carbon dioxide in the atmosphere appears to be increasing.3. Explain why many scientists think that the Earth’s climate may be becoming increasingly warmer.4. Describe what a warmer Earth might be like.
25 Greenhouse affect Traps sun energy Major greenhouse gases (absorb and radiate heat):Water vapor, CO2, CFCs, methane, and nitrous oxides
27 KeelingStarted measuring CO2 levels1958 – 314 ppm2000 – 368 ppmIncreased use of fossil fuelsLevels have normal seasonal fluctuations
28 Glaciers and poles melt Increase of CO2 could cause a global rise in temperature (global warming)Glaciers and poles meltSea level rise
29 AffectsIncrease of global temperatureRise of sea levelLoss of coastlineAgricultureDroughts or too much rain
30 Some scientists believe that the warming is part of natural climatic variability What is the evidence?
31 Consequences of a Warmer Earth These things could happen rather caused by nature or man….Melting of ice and sea level riseGlobal weather patterns changeHuman health problemsAgriculturePlants and animals
32 How do we reduce the risk? ReforestationReduce dependence of on fossil fuelsReduce use of harmful chemicalsInternational agreements -Kyoto Protocol