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Atmosphere and Climate Change

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Atmosphere and Climate Change Chapter 13 – PowerPoint PPT presentation

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Title: Atmosphere and Climate Change


1
Atmosphere and Climate Change
  • Chapter 13

2
Climate and Climate Change
  • Climate- long term prevailing weather conditions
    in a particular place
  • Factors that influence climate
  • Latitude
  • Atmospheric circulation patterns
  • Oceanic circulation patterns
  • Local geography
  • Solar activity
  • Volcanic activity

3
Climate and climate change
  • Latitude- distance north or south of the equator
  • Low latitudes- 12 hours of sun light, high
    temperatures year around, no seasons
  • High latitudes- sun light varies between summer
    and winter months, lower temperature than areas
    near the equator

4
Climate and Climate Change
  • Atmospheric circulation-
  • Cold air sinks
  • Warm air rises
  • Warm air holds more moisture than cold air
  • Sun light shines on the ground and warms the air
    above it. The warm air rises and cooler air
    moves in to fill its place. This causes wind.
  • The uneven heating of the earths surface and the
    spin of the earth causes prevailing winds.

5
Climate and Climate Change
6
Climate and Climate Change
  • Oceanic circulation patterns
  • Surface currents are mainly affected by
    prevailing winds
  • El Nino- short term (6-18 months), warm water is
    pushed east, causes increased rainfall in the
    southern US and central America, causes drought
    in Indonesia and Australia
  • La Nina- cooler than normal water- opposite
    effects to El Nino

7
Climate and Climate Change
  • Ocean Circulation Patterns
  • Pacific Decadal Oscillation- long term (20-30
    year cycle), affects climate over North America,
    affects surface water temperatures, air
    temperatures, and precipitation patterns.

8
Climate and Climate Change
  • Topography-
  • Elevation- temperature drops 6 C for every 1000
    ft
  • Mountains can affect precipitation
  • Sun
  • Solar maximum- increased amounts of UV radiation
    can increase stratospheric temperatures as well
    as lower atmospheric temperature.
  • Volcanic eruptions
  • Sulfur dioxide emitted from a volcano can reach
    the upper atmosphere and react with water vapor
    and dust to form a bright haze. This haze
    reflects sunlight back into space cooling the
    earth.

9
Climate and Climate Change
10
Climate and Climate Change
  • Seasonal Changes in Climate
  • Earths axis is tilted at 23.5
  • Summer northern hemisphere leans toward the sun
  • Winter southern hemisphere leans toward the sun

11
Climate and Climate Change
12
Climate and Climate Change
13
The Ozone Shield
  • Ozone layer- an area of the stratosphere where
    ozone is highly concentrated
  • Ozone a molecule made of 3 oxygen atoms
  • Absorbs most of the UV light that reaches the
    earth from the sun

14
The Ozone Shield
  • Ozone depletion-
  • Chlorofluorocarbons (CFCs)- a class of
    human-made chemicals that might damage ozone
  • Nonpoisonous, nonflammable, non-corrosive
  • Used as..
  • coolant in refrigerators
  • To make foam
  • Spray propellant
  • Chemically stable at earths surface
  • Over a 20-30 year period CFCs make there way to
    the upper atmosphere.

15
The Ozone Shield
16
The Ozone Shield
  • Scientist have estimated that a single chlorine
    atom can destroy 100,000 ozone molecules.

17
The Ozone Shield
  • Thinning of the ozone layer was reported in 1985
    (50-98) around Antarctica.
  • Polar stratospheric clouds form causing CFCs to
    breakdown to Cl. The Cl reacts with the ozone in
    the presence of UV light.
  • UV light kills living cells

18
The Ozone Shield
19
The Ozone Shield
  • 1987 Montreal Protocol- a group of nations agreed
    to decrease the production of CFCs
  • 1992- developed nations agreed to ban the use and
    production of CFCs

20
Global Warming
  • Greenhouse effect- process of heat absorption by
    gasses in the earths atmosphere
  • Greenhouse gases
  • Water vapor
  • Carbon dioxide
  • CFCs
  • Methane
  • Nitrous oxide

21
Global Warming
  • Most scientist think that increased levels of
    greenhouse gases will cause increases in global
    atmospheric temperature, but not all scientist
    agree.
  • Global CO2 levels fluctuate throughout the year
    (high in winter and low in summer)

22
Global Warming
23
Global Warming
  • Some scientist believe that the warming trend
    that started at the beginning of the 20th century
    will continue. Other believe that the warming
    trend is part of a natural occurrence of
    fluctuating temperatures that appear throughout
    time.

24
Global Warming
  • The Consequences
  • Melting ice and rising sea level
  • Weather pattern changes
  • Stronger hurricanes and typhoons
  • Change in precipitation patterns
  • Human health problems
  • Heat related deaths
  • Increase in ground level ozone causing reparatory
    disease
  • Increase in disease carrying insects

25
Global Warming
  • Consequences- cont
  • Agriculture
  • Droughts
  • Diseased crop yields may increase
  • Effects on plants and animals
  • Alter habitat ranges
  • Alter available food sources (zooplankton)

26
Global Warming
  • Recent findings- IPCC
  • Third Assessment Report
  • Average global temperature increased 0.6 C during
    20th century
  • Snow cover and ice extent decreased
  • Global sea level has risen
  • Increase in greenhouse gases due to human
    activities

27
Global Warming
  • Reducing Risk
  • Kyoto Protocol (1997)
  • 55 of nations ratify
  • Developed nations decrease emissions by 5 below
    their 1990 levels by 2012
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