Transcript Atmospheric and Climate Change

Atmospheric and Climate
Change
Chapter 13
13-1 Climate and Climate Change
Objectives
1.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.
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.
 Latitude
–Amount of solar energy
that reaches the surface
 Atmospheric circulation
–Warm air rises, cold air
sinks
–Warm air holds more
moisture
–Heat differences cause
winds
 Global Circulation Patterns
– Patterns are disrupted at the equator
 Cool air rises at the equator and is forced to the
poles
 Air condenses and 30 degrees N and S
 Air sinks, causes water to evaporate from land
 Flows back to the poles or equator
 Prevailing winds (westerlies)
– Blow from one direction most of the year
– Trade winds at 30 degrees N and S
 Ocean Circulation patterns
– Hold vast amounts of heat
– Currents redistribute heat
– Cold and warm currents
–El Nino – Southern
Oscillation
 Short-term periodic change in the
location of warm and cold currents
in the Pacific ocean
 Winds in west Pacific become
stronger and push warm water
eastward
 Causes drought in Indonesia and
Australia
–La Nina Water in the Pacific is
colder than usual
–Pacific Decadal oscillation
Long term change in
currents
 Local geography
–Mountain ranges
 Seasonal changes
 Solar activity
–Increase UV and energy
from the sun
 Volcanic activity
–Releases gases (SO2)and
dust into the atmosphere
which affects weather
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.
Ozone Shield
 Ozone layer – ozone is
concentrated
–O3
–Absorbs UV – protects DNA
of all living things
Chemicals that cause Ozone
depletion
–CFC’s (chlorofluorocarbons)
damages ozone
Stable at surface but reacts
in atmosphere
destroys ozone molecules
Ozone hole
 Thinning of atmospheric ozone
that occurs at the poles
–First report in 1985, but noticed
in 1970’s
– Chlorine reacts with ozone and destroys it
 Form in polar stratospheric clouds
– Can’t be replaced by ground level ozone
 Affects
–Increased UV radiation
Damages DNA
Cancer
Weaker immune system
Kills phytoplankton
Harms amphibians, marine
life, and plants
 Protection of Ozone
–International agreements
(Montreal Protocol) to
eliminate CFC use
US pledged to ban all
substances by 200
–Did we do it??
Level is going down
It will be years before
affects of programs can be
measured because CFCs
stay active for 60-120
years
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.
Greenhouse affect
 Traps sun energy
Major greenhouse gases
(absorb and radiate heat):
Water vapor, CO2, CFCs,
methane, and nitrous
oxides
 Keeling
– Started measuring CO2 levels
 1958 – 314 ppm
 2000 – 368 ppm
–Increased use of fossil fuels
– Levels have normal seasonal fluctuations
–Increase of CO2 could cause
a global rise in temperature
(global warming)
Glaciers and poles melt
–Sea level rise
 Affects
–Increase of global
temperature
–Rise of sea level
Loss of coastline
–Agriculture
Droughts or too much
rain
 Some scientists believe that the
warming is part of natural climatic
variability
–What is the evidence?
Consequences of a Warmer Earth
These things could happen rather caused
by nature or man….
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Melting of ice and sea level rise
Global weather patterns change
Human health problems
Agriculture
Plants and animals
How do we reduce the risk?
 Reforestation
 Reduce dependence of on
fossil fuels
 Reduce use of harmful
chemicals
 International agreements –Kyoto Protocol