Chapter 2 Energy Balance in Climatology Atmosphere 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 motion Radiation- E transfer via electromagnetic transference Chapter 2 Energy Balance in Climatology Atmosphere 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 motion Radiation- E transfer via electromagnetic transference

Kinds of Energy Radiation- the emission of energy on the form of waves Kinetic- energy due to motion = 1 / 2 m x v 2 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 / 2 m x v 2 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

SunSunlightEarth’s SurfaceTerrestrial Atomic Energy Radiation (all waves) HeatRadiation (longwave) SunlightPhotosynthesisFood chain RadiationChemical energy Water vaporRaindrop fallingFriction with air Potential EnergyKinetic EnergyHeat Examples- energy related to phenomena

Solar Radiation: The driving factor Radiation (Electromagnetic energy) released, absorbed & reflected by all things travels as both a particle and a wave is affected by - - gravity, magnetism, and atmosphere composition, distance, angle of incidence provides Earth with an external source of energy

Wavelength and frequency are inversely related to one another Wavelength (1/  Frequency The electromagnetic spectrum

Nature of radiative energy (Radiation) electromagnetic travels as waves and also acts like particle All things radiate energy a function of Temperature Stephan-Boltzman’s Law F = s T 4 Where F is radiation Flux s is a constant 5.67 x W/m 2 K 4 T is the temperature in ° Kelvin The hotter the object, the more energy it radiates F = (5.67 x ) x (6000) 4 = 73,400,000 W/ m 2 (Sun) F = (5.67 x ) x (288) 4 = 390 W/ m 2 (Earth) Nature of radiative energy (Radiation) electromagnetic travels as waves and also acts like particle All things radiate energy a function of Temperature Stephan-Boltzman’s Law F = s T 4 Where F is radiation Flux s is a constant 5.67 x W/m 2 K 4 T is the temperature in ° Kelvin The hotter the object, the more energy it radiates F = (5.67 x ) x (6000) 4 = 73,400,000 W/ m 2 (Sun) F = (5.67 x ) x (288) 4 = 390 W/ m 2 (Earth)

In general, temperature of emitting body controls wavelength of outgoing energy hotter = shorter cooler = longer Wein’s Law allows us to predict which wavelength will be most abundant. max = 2897/T Example: Sun’s surface temperature is 6000° K max = 2897/6000 = 0.48  m Thus, 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 Law allows us to predict which wavelength will be most abundant. max = 2897/T Example: Sun’s surface temperature is 6000° K max = 2897/6000 = 0.48  m Thus, most of sun’s energy should be at a wavelength of 0.48  m

0.48

Solar Structure Sun 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 climatology Photosphere- 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 Structure Sun 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 climatology Photosphere- 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

Chromosphere A 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 Chromosphere A 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 CoronaSolar Photosphere Sun spots

What happens to solar radiation? It decreases with distance traveled outward Inverse square law F rec = F (1/d 2 ) where F = radiation from Sun F rec = 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 Sun F rec 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 F rec = F (1/d 2 ) where F = radiation from Sun F rec = 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 Sun F rec 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 <---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

Albedo A measure of the amount of reflected radiation Some things reflect radiation better than others - - "dry" or "cold" Snow & Ice = high albedo - - water = moderate for visible, low for infrared - - plants= moderate for visible Land absorbs and releases radiative energy quicker than water Albedo = ________________ incident radiation reflected radiation *

Typical albedos of various surfaces to incoming solar radiation Type of surfacePercent reflected energy (Albedo) Fresh Snow % Old Snow % Water 0°99% 10°35% 30°6% 90°2% Clouds Cumulus % Stratus % Cirrus % Forest5 - 20% Grass % Sand % Plowed soil5 - 25% Crops3 - 15% Concrete % Earth as a Planet30%

Reflection energy is bounced away without being absorbed or transformed Scattering energy is diffused or scattered into different wavelengths related to composition and thickness of atmosphere Absorption some gases and aerosols capture (absorb) energy energy is typically re-released as longer wavelength radiative energy Transmissivity The amount of radiation that actually gets through to the surface Reflection energy is bounced away without being absorbed or transformed Scattering energy is diffused or scattered into different wavelengths related to composition and thickness of atmosphere Absorption some gases and aerosols capture (absorb) energy energy is typically re-released as longer wavelength radiative energy Transmissivity 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 Surface InflowOutflow Solar radiation50Earth radiation114 Sky radiation96Latent Heat20 total146Conduction12 total146 Energy balance of Atmosphere InflowOutflow Solar Radiation20Radiation to space63 Condensation20Radiation to Surface96 Earth Radiation107total159 Conduction12 total159 Energy Balance of Earth InflowOutflow Solar radiation100Reflected Radiation30 total100Sky radiation to space63 Earth radiation to space7 total100

Long wave Earth radiation to space Long wave radiation from atmosphere Earth Atmosphere Incoming solar radiation; Solar Constant Sensible heat Latent heat Long wave Earth radiation solar radiation absorbed by atmosphere solar radiation reflected and scattered back to space by atmosphere and surface Long wave sky radiation

Distribution of energy An energy energy budget example