Chapter 23

The Atmosphere, Climate, and Global Warming

Videos

• Layers of the atmosphere, sorry, a bit boring, but all the info you need here.

• Greenhouse effect

• Global Warming

The Atmosphere

• The thin layer of glass that envelops the Earth

• Chemical reactions

• Atmospheric circulation produces weather and climates

Climate

• Climate: – the representative or characteristic atmospheric

conditions for a region on Earth

• Microclimate– The climate of a very small local area

• Urban Dust Dome– Polluted urban air produced by the combination of

lingering air and abundance of particulates and other pollutants in the urban air mass

Climatic Change

• Major climatic changes have occurred during the past 2 million years

• Appearances and retreats of glaciers

• During the past 100 years, the mean global annual temperature ahs increased by .5 degrees Celsius

Global Warming

• A natural or human induced increase in the average global temperature of the atmosphere near the earth’s surface

• 4 factors– Amount of sunlight Earth receives– Amount of sunlight Earth reflects– Retention of heat by atmosphere– Evaporation and condensation of water vapor

Electromagnetic Radiation and Earth’s Energy Balance

• Electromagnetic spectrum– The collection of all possible wavelengths of

electromagnetic energy, considered a continuous range

The Greenhouse Effect

• Greenhouse Effect– The process of trapping heat in the atmosphere– Water vapor and several other gases warm the

Earth’s atmosphere because they absorb and emit radiation

• Greenhouse Gasses– Gasses that have a greenhouse effect– Water vapor, carbon dioxide, methane, CFCs

Global Warming

• Negative and Positive feedback cycles affect the atmosphere

• Increase in emission of greenhouse gasses

• Solar Forcing, Natural Cycles, Aerosols (global dimming), Volcanic Eruptions, El Nino

Effects of Global Warming

• Changes in climatic patterns

• Rise in sea level

• Changes in biosphere

Global Climate Patterns• Earth’s global climate patterns

– Are determined largely by the input of solar energy and the planet’s movement in space

• Sunlight intensity– Plays a major part in determining the Earth’s climate

patterns

Figure 50.10

Low angle of incoming sunlight

Sunlight directly overhead

Low angle of incoming sunlight

North Pole60N

30NTropic ofCancer

0 (equator)

30S

60S

Atmosphere

LALITUDINAL VARIATION IN SUNLIGHT INTENSITY

Tropic ofCapricorn

South pole

Figure 50.10

June solstice: NorthernHemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins inSouthern Hemisphere.

March equinox: Equator faces sun directly;neither pole tilts toward sun; all regions on Earthexperience 12 hours of daylight and 12 hours ofdarkness.

60N30N

0 (equator)

30S

Constant tiltof 23.5

September equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours ofdaylight and 12 hours of darkness.

December solstice: NorthernHemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere.

SEASONAL VARIATION IN SUNLIGHT INTENSITY

Descendingdry airabsorbsmoisture

Ascendingmoist airreleasesmoisture

Descendingdry airabsorbsmoisture

30 23.5 0 23.5 30Aridzone Tropics

Aridzone

60N

30N

0 (equator)

30S

60S

GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS

• Air circulation and wind patterns– Play major parts in determining the Earth’s climate

patterns

Figure 50.10

GLOBAL WIND PATTERNS

Westerlies

Northeast trades

Doldrums

Southeast trades

Westerlies

AntarcticCircle

60S

30S

0(equator)

30N

60N

ArcticCircle

Figure 50.10

Adjustments to Global Warming

• Evidence based decision-making???

• Mitigate warming through reduction of greenhouse gasses

• Energy conservation

• Alternative energy sources

• Danger: rapid climatic change

Antarctic Heat Sink

Not always that easy to understand…

• Ice levels don’t always decrease neatly with AGW

• Check this out as well.