Atmosphere and Climate Change

Atmosphere and Climate Atmosphere and Climate ChangeChange

Chapter 13Chapter 13

Climate and Climate ChangeClimate and Climate Change

Climate- long term prevailing weather Climate- long term prevailing weather conditions in a particular placeconditions in a particular place

Factors that influence climateFactors that influence climate– LatitudeLatitude– Atmospheric circulation patternsAtmospheric circulation patterns– Oceanic circulation patternsOceanic circulation patterns– Local geographyLocal geography– Solar activitySolar activity– Volcanic activityVolcanic activity

Climate and climate changeClimate and climate change

Latitude- distance north or south of the Latitude- distance north or south of the equatorequator– Low latitudes- 12 hours of sun light, high Low latitudes- 12 hours of sun light, high

temperatures year around, no seasonstemperatures year around, no seasons– High latitudes- sun light varies between summer High latitudes- sun light varies between summer

and winter months, lower temperature than and winter months, lower temperature than areas near the equatorareas near the equator

Climate and Climate ChangeClimate and Climate Change Atmospheric circulation- Atmospheric circulation-

1.1. Cold air sinksCold air sinks

2.2. Warm air risesWarm air rises

3.3. Warm air holds more moisture than cold airWarm air holds more moisture than cold air– Sun light shines on the ground and warms the Sun light shines on the ground and warms the

air above it. The warm air rises and cooler air air above it. The warm air rises and cooler air moves in to fill its place. This causes wind.moves in to fill its place. This causes wind.

– The uneven heating of the earth’s surface and The uneven heating of the earth’s surface and the spin of the earth causes prevailing winds.the spin of the earth causes prevailing winds.



Oceanic circulation patternsOceanic circulation patterns– Surface currents are mainly affected by Surface currents are mainly affected by

prevailing windsprevailing winds– El Nino- short term (6-18 months), warm water El Nino- short term (6-18 months), warm water

is pushed east, causes increased rainfall in the is pushed east, causes increased rainfall in the southern US and central America, causes southern US and central America, causes drought in Indonesia and Australiadrought in Indonesia and Australia

– La Nina- cooler than normal water- opposite La Nina- cooler than normal water- opposite effects to El Ninoeffects to El Nino


Ocean Circulation PatternsOcean Circulation Patterns– Pacific Decadal Oscillation- long term (20-30 Pacific Decadal Oscillation- long term (20-30

year cycle), affects climate over North America, year cycle), affects climate over North America, affects surface water temperatures, air affects surface water temperatures, air temperatures, and precipitation patterns.temperatures, and precipitation patterns.

Climate and Climate ChangeClimate and Climate Change Topography- Topography-

– Elevation- temperature drops 6 C for every 1000 ftElevation- temperature drops 6 C for every 1000 ft– Mountains can affect precipitationMountains can affect precipitation

SunSun– Solar maximum- increased amounts of UV radiation can Solar maximum- increased amounts of UV radiation can

increase stratospheric temperatures as well as lower increase stratospheric temperatures as well as lower atmospheric temperature.atmospheric temperature.

Volcanic eruptionsVolcanic eruptions– Sulfur dioxide emitted from a volcano can reach the Sulfur dioxide emitted from a volcano can reach the

upper atmosphere and react with water vapor and dust upper atmosphere and react with water vapor and dust to form a bright haze. This haze reflects sunlight back to form a bright haze. This haze reflects sunlight back into space cooling the earth. into space cooling the earth.



Seasonal Changes in ClimateSeasonal Changes in Climate– Earth’s axis is tilted at 23.5Earth’s axis is tilted at 23.5– Summer = northern hemisphere leans toward Summer = northern hemisphere leans toward

the sunthe sun– Winter = southern hemisphere leans toward the Winter = southern hemisphere leans toward the

sunsun



The Ozone ShieldThe Ozone Shield

Ozone layer- an area of the stratosphere Ozone layer- an area of the stratosphere where ozone is highly concentratedwhere ozone is highly concentrated– Ozone = a molecule made of 3 oxygen atomsOzone = a molecule made of 3 oxygen atoms– Absorbs most of the UV light that reaches the Absorbs most of the UV light that reaches the

earth from the sunearth from the sun

The Ozone ShieldThe Ozone Shield Ozone depletion- Ozone depletion-

– Chlorofluorocarbons (CFC’s)- a class of human-Chlorofluorocarbons (CFC’s)- a class of human-made chemicals that might damage ozonemade chemicals that might damage ozone Nonpoisonous, nonflammable, non-corrosiveNonpoisonous, nonflammable, non-corrosive Used as..Used as..

– coolant in refrigeratorscoolant in refrigerators– To make foamTo make foam– Spray propellantSpray propellant

Chemically stable at earth’s surfaceChemically stable at earth’s surface Over a 20-30 year period CFC’s make there way to Over a 20-30 year period CFC’s make there way to

the upper atmosphere.the upper atmosphere.


The Ozone Shield The Ozone Shield

Scientist have estimated that a single Scientist have estimated that a single chlorine atom can destroy 100,000 ozone chlorine atom can destroy 100,000 ozone molecules.molecules.


Thinning of the ozone layer was reported in Thinning of the ozone layer was reported in 1985 (50-98%) around Antarctica. 1985 (50-98%) around Antarctica. – Polar stratospheric clouds form causing CFC’s Polar stratospheric clouds form causing CFC’s

to breakdown to Cl. The Cl reacts with the to breakdown to Cl. The Cl reacts with the ozone in the presence of UV light.ozone in the presence of UV light.

UV light kills living cellsUV light kills living cells


The Ozone ShieldThe Ozone Shield 1987 Montreal Protocol- a group of nations 1987 Montreal Protocol- a group of nations

agreed to decrease the production of CFC’sagreed to decrease the production of CFC’s 1992- developed nations agreed to ban the 1992- developed nations agreed to ban the

use and production of CFC’s use and production of CFC’s

Global WarmingGlobal Warming

Greenhouse effect- process of heat Greenhouse effect- process of heat absorption by gasses in the earths absorption by gasses in the earths atmosphereatmosphere

Greenhouse gasesGreenhouse gases– Water vaporWater vapor– Carbon dioxideCarbon dioxide– CFC’sCFC’s– MethaneMethane– Nitrous oxideNitrous oxide

Global WarmingGlobal Warming Most scientist think that increased levels of Most scientist think that increased levels of

greenhouse gases will cause increases in greenhouse gases will cause increases in global atmospheric temperature, but not all global atmospheric temperature, but not all scientist agree.scientist agree.

Global COGlobal CO22 levels fluctuate throughout the levels fluctuate throughout the

year (high in winter and low in summer)year (high in winter and low in summer)


Global WarmingGlobal Warming Some scientist believe that the warming trend that Some scientist believe that the warming trend that started at the beginning of the 20started at the beginning of the 20 thth century will century will continue. Other believe that the warming trend is continue. Other believe that the warming trend is part of a natural occurrence of fluctuating part of a natural occurrence of fluctuating temperatures that appear throughout time.temperatures that appear throughout time.


The ConsequencesThe Consequences– Melting ice and rising sea levelMelting ice and rising sea level– Weather pattern changesWeather pattern changes

Stronger hurricanes and typhoonsStronger hurricanes and typhoons Change in precipitation patternsChange in precipitation patterns

– Human health problemsHuman health problems Heat related deathsHeat related deaths Increase in ground level ozone causing reparatory Increase in ground level ozone causing reparatory

diseasedisease Increase in disease carrying insectsIncrease in disease carrying insects


Consequences- con’tConsequences- con’t– AgricultureAgriculture

DroughtsDroughts Diseased crop yields may increaseDiseased crop yields may increase

– Effects on plants and animalsEffects on plants and animals Alter habitat rangesAlter habitat ranges Alter available food sources (zooplankton)Alter available food sources (zooplankton)


Recent findings- IPCCRecent findings- IPCC– Third Assessment ReportThird Assessment Report

Average global temperature increased 0.6 C during Average global temperature increased 0.6 C during 2020thth century century

Snow cover and ice extent decreasedSnow cover and ice extent decreased Global sea level has risenGlobal sea level has risen Increase in greenhouse gases due to human Increase in greenhouse gases due to human

activitiesactivities

Global WarmingGlobal Warming Reducing RiskReducing Risk

– Kyoto Protocol (1997)Kyoto Protocol (1997) 55% of nations ratify55% of nations ratify Developed nations decrease emissions by 5% below Developed nations decrease emissions by 5% below

their 1990 levels by 2012their 1990 levels by 2012

Documents

Atmosphere and Climate Change