Summary of lecture 1
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Summary of Lecture 1. Introduction to Earth’s atmosphere origin composition structure comparison with other planets Stefan’s law. Solar and Terrestrial Radiation. Sun ~ 6000 K UV/vis λ max ~0.6 μ m Solar flux =1370 Wm -2 S (1- α )/4= σ T E 4 Earth ~ 255 K IR λ max ~ 12 μ m.

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Summary of Lecture 1

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Summary of lecture 1

Summary of Lecture 1

  • Introduction to Earth’s atmosphere

    • origin

    • composition

    • structure

    • comparison with other planets

  • Stefan’s law


Solar and terrestrial radiation

Solar and Terrestrial Radiation

  • Sun ~ 6000 K

  • UV/visλmax~0.6μm

  • Solar flux =1370 Wm-2

  • S (1-α)/4=σTE4

  • Earth ~ 255 K

  • IR λmax~ 12μm


Uv absorption

DUV

UVb

UVa /

Visible

InfraRed

UVc

UV absorption


Absorption by atmospheric gases

Absorption by atmospheric gases


Solar energy received

Solar energy received


Notes

Notes:

  • Surface has Ts=288 K and radiates σTs4 = 400 Wm-2(117 units).

  • Atmosphere at 250 K radiates 220 Wm-2 (64 units), both up and down.

  • 30% of surface radiation is reflected by the atmosphere (32 units), giving a total downward flux of 96 units.

  • Non-radiative flux of 100 Wm-2 (30 units) drives the atmospheric circulation and weather


Radiation balance

Radiation Balance


Seasonal net ir radiation

Seasonal net IR radiation


Summary of lecture 1

Global Climate

Net short, long and global radiation entering and leaving the top of our atmosphere measured by satellite.

Data are from the Earth Radiation Budget Experiment (ERBE)


Global warming

Global Warming


Summary of lecture 1

JFM 2002 is clearly

the warmest ever

Temperature rise °C

Global temperatures 1860-2001


Summary of lecture 1

Change in extent of Arctic sea ice

Arctic sea ice extent, million km2


Rising co 2 levels

Rising CO2 levels


Summary of lecture 1

700

600

500

400

350

Carbon dioxide concentration

in the atmosphere, due to three emissions scenarios

Business as usual emissions

Constant 1990 emissions

50% reduction in emissions

CO2 concentration ppm


Global temperature rise

Global temperature rise

IPCC A1FI emissions

A2 emissions

B2 emissions

B1 emissions

Global temperature rise, degrees C


Summary of lecture 1

Hadley Centre

Components of sea-level rise


Pattern of annual temperature changes 2080s relative to present day

Met Office / Hadley Centre

A1FI emissions scenario

0

1

2

3

4

5

6

Pattern of annual temperature changes2080s relative to present day


Temperature rise

winter

summer

Hadley Centre

Hadley Centre

°C

Temperature rise

Medium-high emissions scenario, 2080s


Pattern of annual precipitation changes 2080s relative to present day

Met Office / Hadley Centre

A1FI emissions scenario

3

2

1

0.5

0.25

0

0.25

0.5

1

2

3

Pattern of annual precipitation changes2080s relative to present day


Change in precipitation

Medium-high emissions scenario, 2080s

winter

summer

Hadley Centre

Hadley Centre

Change in precipitation

%


Summary of lecture 1

Change in surface temperature

with forced THC collapse, but without change in greenhouse gases

Hadley Centre

Deg C


Carbon cycle

Carbon Cycle

  • photosynthesis

respiration


Predicted temperature rise

Predicted temperature rise

  • Assuming current levels of CO2 emission


Changes in precipitation predicted for doubling co 2 levels

Changes in precipitation predicted for doubling CO2 levels


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