Greenhouse Science .

1. 1
The Greenhouse Science
Outline
 Greenhouse effect
 Energy Balance
 Activities

2. The Atmosphere

3. Principal Atmospheric Gases
GAS MASS
Nitrogen 75%
Oxygen 23%
Argon 1%
Water Vapor 0.3%
CO2 0.06%

4. Principal Atmospheric Gases
GAS MASS
Nitrogen 75%
Oxygen 23%
Argon 1%
Water Vapor 0.3%
CO2 0.06%
Greenhouse gases

5. Earth’s Energy BalanceEarth’s Energy Balance
 Energy entering top of atmosphere
 Energy entering the Earth’s surface
= Energy leaving top of atmosphere= Energy leaving top of atmosphere
= Energy leaving Earth’s surface= Energy leaving Earth’s surface

6. Solar Radiation (Sunlight)
 Sunlight is primarily made up of the
following:
– Visible Light (44%)Visible Light (44%)
– Infrared Radiation (48%)Infrared Radiation (48%)
– Ultraviolet Radiation (7%)Ultraviolet Radiation (7%)
Unit: 1 µm =
0.000001 m

7. Energy from the Sun
 Obviously, the Sun provides the Earth with it’s energy. The
question is, how much of the Sun’s energy does the Earth get?
 Sun’s energy is either
– Scattered (reflected away) or
– Absorbed
 Scattering happens by bouncing off
– Particles in the atmosphere
– Earth’s surface
 Absorption happens when certain gases absorb the energy
– The reality is the only certain gases absorb certain
wavelengths.

8. Incoming solar radiationIncoming solar radiation
 Each ‘beam’ of incoming sunlight can be either:
– Reflected back to space:
 CloudsClouds
 AtmosphereAtmosphere
 SurfaceSurface
– Or absorbed; either by atmosphere (e.g.
clouds or ozone) or Earth’s surface.
AlbedoAlbedo

10. Absorption of radiation
 Absorption of shortwave radiation by atmospheric gas
molecules is fairly weak;
– most absorption of shortwave radiation occurs at the
Earth’s surface.
 Most gases do not interact strongly with longwave
radiation, however
– Greenhouse gas molecules absorb certainGreenhouse gas molecules absorb certain
wavelengths of longwave radiation.wavelengths of longwave radiation.

11. Absorption of
radiation in the
Earth’s
atmosphere

12. Longwave radiation is
emitted from surface.
Some surface
radiation
escapes to
space
Most
outgoing
longwave is
absorbed in
atmosphere
(by
greenhouse
gases)
Greenhouse
gases emit
longwave
upward and
downward
Some
atmospheric
radiation
escapes to space
Some
atmospheric
radiation is
absorbed at the
surface

15. Greenhouse EffectGreenhouse Effect
Sequence of steps:
1.1. Solar radiation absorbed by earth’s surface.Solar radiation absorbed by earth’s surface.
2.2. Earth gives off infrared radiation.Earth gives off infrared radiation.
3.3. Greenhouse gases absorb some of the Earth’sGreenhouse gases absorb some of the Earth’s
infrared radiation.infrared radiation.
4.4. Greenhouse gases (water and CO2) give offGreenhouse gases (water and CO2) give off
infrared radiation in all directions.infrared radiation in all directions.
5.5. Earth absorbs downward directed infrared radiationEarth absorbs downward directed infrared radiation
Result: warmer surface temperature

17. Earth’s Greenhouse Effect
 Without the greenhouse effect, the surface
temperature of Earth would be
– Very Cold (-18°C)
 Greenhouse gases play an important role in
shaping climate.
– More GHGs – warmer climateMore GHGs – warmer climate
– Less GHGs – cooler climateLess GHGs – cooler climate

18. Activity
Draw a diagram showing how the
earth is heated by the Sun.
Include arrows and/or lines to
indicate the ‘Energy Balance” of the
earth.
Energy Balance – Energy coming in
and energy going out.
In your diagram, include how clouds
absorb, reflect and emit energy.

19. 1. What percentage of the sun’s radiation is
a) absorbed by the Earth’s surface?
b) absorbed by the atmosphere
c) reflected out to space?
2. What percentage of the energy received by the earth’s surface
comes directly from greenhouse gas emissions?
3. If the sun’s radiation was to increase by 10%, how would the
following energy units change (increase, decrease or stay the
same)
a) Energy gained by the Earth’s surface.
b) Energy lost by the Earth’s surface.
c) Energy emitted by greenhouse gases.
d) Energy lost to space.
Activity 2