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Chapter 2 Energy Balance in ClimatologyAtmosphere gets most of it’s energy from the sun
•not directly though!Energy input is concentrated in certain regions
must be moved from one location to another by one of earth’s systems
Atmosphere (air) or hydrosphere (oceans)Transference of Energy (E) from the sun to the earth’s atmosphere is done by:
Conduction- E transfer by molecular contact
Convection- E transfer by motionRadiation- E transfer via electromagnetic transference
Chapter 2 Energy Balance in ClimatologyAtmosphere gets most of it’s energy from the sun
•not directly though!Energy input is concentrated in certain regions
must be moved from one location to another by one of earth’s systems
Atmosphere (air) or hydrosphere (oceans)Transference of Energy (E) from the sun to the earth’s atmosphere is done by:
Conduction- E transfer by molecular contact
Convection- E transfer by motionRadiation- E transfer via electromagnetic transference
Kinds of Energy
Radiation- the emission of energy on the form of waves
Kinetic- energy due to motion = 1/2m x v2
Potential- Energy stored as position potentially converted to Kinetic Energy
Chemical- Energy used or released in chemical reactions
Atomic- Energy released from an atomic nucleus at the expense of its mass
Electrical- Energy exerted as a force on objects with an electrical charge
Heat- aggregate energy of motions of atoms and molecules
Kinds of Energy
Radiation- the emission of energy on the form of waves
Kinetic- energy due to motion = 1/2m x v2
Potential- Energy stored as position potentially converted to Kinetic Energy
Chemical- Energy used or released in chemical reactions
Atomic- Energy released from an atomic nucleus at the expense of its mass
Electrical- Energy exerted as a force on objects with an electrical charge
Heat- aggregate energy of motions of atoms and molecules
Sun Sunlight Earth’s Surface Terrestrial
Atomic Energy
Radiation(all
waves)
Heat Radiation(longwave)
Sunlight Photosynthesis
Food chain
Radiation Chemical energy
Chemical energy
Water vapor Raindrop falling
Friction with air
Potential Energy
Kinetic Energy Heat
Examples- energy related to phenomenaExamples- energy related to phenomena
Solar Radiation: The driving factorSolar Radiation: The driving factor• • Radiation (ElectromagneticRadiation (Electromagnetic
energy) released, absorbed &energy) released, absorbed &reflected by all thingsreflected by all things
• • travels as both a particle andtravels as both a particle and
a wavea wave
• • is affected by is affected by
-- gravity, magnetism, andgravity, magnetism, and
atmosphere composition,atmosphere composition,distance, angle of incidencedistance, angle of incidence
• • provides Earth with anprovides Earth with an
external source of energyexternal source of energy
Wavelength and frequency are inversely related to one another Wavelength (1/Frequency
The electromagnetic spectrumThe electromagnetic spectrum
Nature of radiative energy (Radiation)electromagnetic travels as waves and also acts like particleAll things radiate energy
a function of Temperature
Stephan-Boltzman’s Law
F = s T 4
Where F is radiation Fluxs is a constant 5.67 x 10-8 W/m2K4
T is the temperature in ° KelvinThe hotter the object, the more energy it radiatesF = (5.67 x 10-8) x (6000)4 = 73,400,000 W/ m2
(Sun)F = (5.67 x 10-8) x (288)4 = 390 W/ m2 (Earth)
Nature of radiative energy (Radiation)electromagnetic travels as waves and also acts like particleAll things radiate energy
a function of Temperature
Stephan-Boltzman’s Law
F = s T 4
Where F is radiation Fluxs is a constant 5.67 x 10-8 W/m2K4
T is the temperature in ° KelvinThe hotter the object, the more energy it radiatesF = (5.67 x 10-8) x (6000)4 = 73,400,000 W/ m2
(Sun)F = (5.67 x 10-8) x (288)4 = 390 W/ m2 (Earth)
In general, temperature of emitting body controls wavelength of outgoing energy
hotter = shorter cooler = longer
Wein’s Lawallows us to predict which
wavelength will be most abundant.max= 2897/T
Example:Sun’s surface temperature is 6000° Kmax = 2897/6000 = 0.48mThus, most of sun’s energy should be at a wavelength of 0.48 m
In general, temperature of emitting body controls wavelength of outgoing energy
hotter = shorter cooler = longer
Wein’s Lawallows us to predict which
wavelength will be most abundant.max= 2897/T
Example:Sun’s surface temperature is 6000° Kmax = 2897/6000 = 0.48mThus, most of sun’s energy should be at a wavelength of 0.48 m
0.48
Solar StructureSun is a fusion reactor-smashes atoms of H into other atoms and makes new, heavier elements and releases a bunch of energy
H + H = He + a lot of energy
Has zones that are important to climatologyPhotosphere- visible part of the sun we see all the time (covered during a solar eclipse)Consists primarily of Hydrogen (90%) and Helium (10%)
This is where the 6000° K temperature comes from
Uneven heat distribution in the 300 km thick layer created by convection currents results in grainy appearance
Solar StructureSun is a fusion reactor-smashes atoms of H into other atoms and makes new, heavier elements and releases a bunch of energy
H + H = He + a lot of energy
Has zones that are important to climatologyPhotosphere- visible part of the sun we see all the time (covered during a solar eclipse)Consists primarily of Hydrogen (90%) and Helium (10%)
This is where the 6000° K temperature comes from
Uneven heat distribution in the 300 km thick layer created by convection currents results in grainy appearance
ChromosphereA wide (up to 1,000,000 Km) but variable zone of burning gases above the photosphere
The gases in this zone move at high velocities and travel outward from the Sun as the solar wind
Also the zone within which sun spots and solar flares occur
Sun spots are cooler regions on the Sun’s surface zones of intense magnetic disturbance
Flares are explosive eruptions of atomic particles and radiation that extend outward for millions of miles and can influence stuff 100’s of millions of miles away
ChromosphereA wide (up to 1,000,000 Km) but variable zone of burning gases above the photosphere
The gases in this zone move at high velocities and travel outward from the Sun as the solar wind
Also the zone within which sun spots and solar flares occur
Sun spots are cooler regions on the Sun’s surface zones of intense magnetic disturbance
Flares are explosive eruptions of atomic particles and radiation that extend outward for millions of miles and can influence stuff 100’s of millions of miles away
Solar Corona Solar Photosphere
Sun spots
What happens to solar radiation? It decreases with distance traveled outward
Inverse square law
Frec = F (1/d2)where F = radiation from Sun
Frec = Radiation received and d = distance from source
d is in astronomical unit (AU) or distance from Sun to Earth = 1
Our distance from the sun controls how much solar energy we get from the SunFrec is very small 1/2,000,000,000 of the total energy produced by the Sun
Several things can happen to that incoming energy
Reflection, Refraction, Scattering, Absorption
What happens to solar radiation? It decreases with distance traveled outward
Inverse square law
Frec = F (1/d2)where F = radiation from Sun
Frec = Radiation received and d = distance from source
d is in astronomical unit (AU) or distance from Sun to Earth = 1
Our distance from the sun controls how much solar energy we get from the SunFrec is very small 1/2,000,000,000 of the total energy produced by the Sun
Several things can happen to that incoming energy
Reflection, Refraction, Scattering, Absorption
How much energy does the Earth receive?
Imagine a sphere with a radius (d) the distance from the Earth to the center of the Sun = 1 AU
Earth--->
<---Sun<---Sun
<---Radius (d)<---Radius (d)
Position affects radiation too• Far away=less radiation
• Titled toward= more radiation• Tilted away=less radiation in North
• Titled toward= more radiation in North
Milankovitch Orbital variations
Eccentricity - change of Earth’s orbit around the Sun from a Circle to an Ellipse. Timeframe: 100,000 years
Obliquity- Change in the tilt of the Earth’s axis of daily rotation. Timeframe: 41,000 yrs
Precession- the wobble of earths tilt or the change in the timing of the tilt of the Earth that forces the northern hemisphere toward the sun- at perihelion vs aphelion 22,000 - to 26,000 years
These work with other systems in the earth to set the pace of climate change
Milankovitch Orbital variations
Eccentricity - change of Earth’s orbit around the Sun from a Circle to an Ellipse. Timeframe: 100,000 years
Obliquity- Change in the tilt of the Earth’s axis of daily rotation. Timeframe: 41,000 yrs
Precession- the wobble of earths tilt or the change in the timing of the tilt of the Earth that forces the northern hemisphere toward the sun- at perihelion vs aphelion 22,000 - to 26,000 years
These work with other systems in the earth to set the pace of climate change
• Sun's energy at 90°
at Tropic of Cancer
• Sun overhead at noon
• Sun's energy at 90°
at Tropic of Capricorn
• Sun overhead at noon
Summer Solstice Winter Solstice
> ~June 21 ~December 21
Albedo
• • A measure of the amount of reflected radiationA measure of the amount of reflected radiation
• • Some things reflect radiation better than othersSome things reflect radiation better than others
- - "dry" or "cold" Snow & Ice = high albedo"dry" or "cold" Snow & Ice = high albedo- - water = moderate for visible, low for infraredwater = moderate for visible, low for infrared- - plants= moderate for visibleplants= moderate for visible
• • Land absorbs and releases radiative energyLand absorbs and releases radiative energyquicker than waterquicker than water
Albedo = ________________incident radiationreflected radiation
*
Typical albedos of various surfaces to incoming solar radiation
Type of surface Percent reflected energy (Albedo)
Fresh Snow 75 - 95%
Old Snow 30 - 40%
Water
0° 99%
10° 35%
30° 6%
90° 2%
Clouds
Cumulus 70 - 90%
Stratus 60 - 84%
Cirrus 44 - 50%
Forest 5 - 20%
Grass 10 - 20%
Sand 35 - 45%
Plowed soil 5 - 25%
Crops 3 - 15%
Concrete 17 - 27%
Earth as a Planet 30%
Reflectionenergy is bounced away without being
absorbed or transformed
Scatteringenergy is diffused or scattered into different wavelengthsrelated to composition and thickness of
atmosphereAbsorption
some gases and aerosols capture (absorb) energy
energy is typically re-released as longer wavelength
radiative energyTransmissivity
The amount of radiation that actually gets through
to the surface
Reflectionenergy is bounced away without being
absorbed or transformed
Scatteringenergy is diffused or scattered into different wavelengthsrelated to composition and thickness of
atmosphereAbsorption
some gases and aerosols capture (absorb) energy
energy is typically re-released as longer wavelength
radiative energyTransmissivity
The amount of radiation that actually gets through
to the surface
Greenhouse effect
Seen as a bad thing by the public because of biased (both the left and the right) or poorly produced media coverage
Greenhouse effect is absolutely essential to Earth’s habitability
Without some means to absorb, block, scatter or transform energy, the Earth would be barren.
Atmosphere does all four things
Most important among these is absorption of longwave (Earth-reemitted or transformed) radiation
Various gases capture this energy which warms the Earth’s atmosphere
Greenhouse effect
Seen as a bad thing by the public because of biased (both the left and the right) or poorly produced media coverage
Greenhouse effect is absolutely essential to Earth’s habitability
Without some means to absorb, block, scatter or transform energy, the Earth would be barren.
Atmosphere does all four things
Most important among these is absorption of longwave (Earth-reemitted or transformed) radiation
Various gases capture this energy which warms the Earth’s atmosphere
Energy balance of Earth’s SurfaceInflow Outflow
Solar radiation 50 Earth radiation 114Sky radiation 96 Latent Heat 20total 146 Conduction 12
total 146
Energy balance of AtmosphereInflow Outflow
Solar Radiation 20 Radiation to space 63Condensation 20 Radiation to Surface 96Earth Radiation 107 total 159Conduction 12total 159
Energy Balance of EarthInflow Outflow
Solar radiation 100 Reflected Radiation 30total 100 Sky radiation to space 63
Earth radiation to space
7
total 100
Long wave Earth radiation to space
Long wave Earth radiation to space
Long wave radiation from atmosphere
Long wave radiation from atmosphere
EarthEarth
AtmosphereAtmosphere
Incoming solar radiation;
Solar Constant
Incoming solar radiation;
Solar Constant
Sensible heatSensible heatLatent heatLatent heat
Long wave Earth radiation
Long wave Earth radiation
solar radiation absorbed by atmosphere
solar radiation absorbed by atmosphere
solar radiation reflected and
scattered back to space by
atmosphere and surface
solar radiation reflected and
scattered back to space by
atmosphere and surface
Long wave sky radiationLong wave sky radiation
-7 -63 -30+100
Distribution of energy
An energy energy budget example