Energy and the Energy and the AtmosphereAtmosphere

OverviewOverview Insolation-Atmosphere Insolation-Atmosphere

InteractionsInteractions ScatteringScattering RefractionRefraction ReflectionReflection AbsorptionAbsorption Heat TransferHeat Transfer

ConductionConduction ConvectionConvection AdvectionAdvection

Greenhouse EffectGreenhouse Effect Energy BalancesEnergy Balances

Atmospheric Radiation BalanceAtmospheric Radiation Balance Surface Energy BudgetSurface Energy Budget

Energy BudgetEnergy Budget

Open Systems model: Shortwave Open Systems model: Shortwave Energy in, Longwave Energy outEnergy in, Longwave Energy out

The Energy Budget describes what The Energy Budget describes what happens to insolation after it happens to insolation after it passes the thermopause, passes passes the thermopause, passes through the atmosphere and through the atmosphere and reaches the surface.reaches the surface. Atmospheric effectsAtmospheric effects Ground effectsGround effects

Insolation-Atmosphere Insolation-Atmosphere InteractionInteraction

Refers to what happens after the Refers to what happens after the intercepted solar radiation intercepted solar radiation enters enters the the atmosphereatmosphere TransmissionTransmission Both short and long wave radiationBoth short and long wave radiation

As light encounters gas molecules and As light encounters gas molecules and particulates in the atmosphere, the particulates in the atmosphere, the pathway that the light follows changespathway that the light follows changes Diffusion (scattering)Diffusion (scattering) RefractionRefraction ReflectionReflection AbsorptionAbsorption

DiffusionDiffusion

The Sun’s rays are essentially parallel The Sun’s rays are essentially parallel as they reach the Earth’s surface.as they reach the Earth’s surface.

As they encounter various particles in As they encounter various particles in the atmosphere, some light rays are the atmosphere, some light rays are bounced in all the different directions.bounced in all the different directions. Diffusion, or scatteringDiffusion, or scattering Some light scattered back into space Some light scattered back into space

(7%)(7%) Some light scattered to the Earth’s Some light scattered to the Earth’s

surface (20%)surface (20%) Diffusion increases as sun angle Diffusion increases as sun angle

decreasesdecreases

Incoming rays

Scattered raysScattered rays

Gaseous mediumGaseous medium

RefractionRefraction Occurs when light passes from one Occurs when light passes from one

medium to anothermedium to another From air to water dropletsFrom air to water droplets From air masses of varying temperature and From air masses of varying temperature and

densitydensity Light ray slows and changes directionLight ray slows and changes direction

Short wavelengths are refracted more than Short wavelengths are refracted more than long wavelengthslong wavelengths

Breaks light into a spectrum; rainbowsBreaks light into a spectrum; rainbows Convection currents in the air (rising hot air) Convection currents in the air (rising hot air)

cause refraction, creating a shimmery cause refraction, creating a shimmery distortiondistortion

miragesmirages

Medium 1Medium 1

Medium 2Medium 2

Incoming rays

Refracted raysRefracted rays

ReflectionReflection Light that bounces off a surfaceLight that bounces off a surface AlbedoAlbedo refers to the amount of light refers to the amount of light

reflected back to spacereflected back to space 31% of incoming sunlight is reflected31% of incoming sunlight is reflected

21% by clouds21% by clouds 7% by diffuse scattering7% by diffuse scattering 3% by the Earth’s surface3% by the Earth’s surface

Mainly short wave radiationMainly short wave radiation Factors that increase albedoFactors that increase albedo

Light colorLight color Smooth surfacesSmooth surfaces Low sun angleLow sun angle

Medium 1Medium 1

Medium 2Medium 2

Incoming rays Reflected raysReflected rays

AbsorptionAbsorption Light that is not part of Earth’s albedoLight that is not part of Earth’s albedo Light that is assimilated by matter (69%)Light that is assimilated by matter (69%)

Ozone in the stratosphere (3%)Ozone in the stratosphere (3%) Clouds (3%)Clouds (3%) Atmospheric gases and dust (18%)Atmospheric gases and dust (18%) Earth’s surface (45%)Earth’s surface (45%)

Including photosynthesisIncluding photosynthesis Causes the matter to increase in Causes the matter to increase in

temperaturetemperature short wave energy is converted to long wave short wave energy is converted to long wave

(infrared)(infrared) including respirationincluding respiration

Absorbed heat energy can be Absorbed heat energy can be transferred in the atmospheretransferred in the atmosphere Heat energy flows from high to low heatHeat energy flows from high to low heat conductionconduction

transfer of heat energy between two objects transfer of heat energy between two objects through physical contactthrough physical contact

Phase changes: Latent heatPhase changes: Latent heat convectionconvection

occurs in mobile media (liquids, gases)occurs in mobile media (liquids, gases) currents: molecules near heat source rise (and currents: molecules near heat source rise (and

cool) while cooler molecules fall (and become cool) while cooler molecules fall (and become heated)heated)

advectionadvection similar to convection, but occurs horizontallysimilar to convection, but occurs horizontally

radiationradiation heat transmitted as infrared radiationheat transmitted as infrared radiation

Greenhouse EffectGreenhouse Effect CloudsClouds

Are variable in coverAre variable in cover Exert tremendous influence on energy budgetExert tremendous influence on energy budget

Increase albedo (albedo forcing)Increase albedo (albedo forcing) Increase greenhouse warming (greenhouse forcing)Increase greenhouse warming (greenhouse forcing)

Certain gases in clouds absorb and reradiate infrared radiationCertain gases in clouds absorb and reradiate infrared radiation Carbon dioxide, water vapor, methaneCarbon dioxide, water vapor, methane

Creates an insulating effectCreates an insulating effect

Different cloud types affect the greenhouse Different cloud types affect the greenhouse effect differentlyeffect differently High thin clouds allow more diffuse light through, High thin clouds allow more diffuse light through,

causing more heat to be trapped (net greenhouse causing more heat to be trapped (net greenhouse forcing)forcing)

Low thick clouds reflect more light out, causing less Low thick clouds reflect more light out, causing less heat to be trapped (net albedo forcing)heat to be trapped (net albedo forcing)

The greenhouse effect has been identified as The greenhouse effect has been identified as the main cause of global warmingthe main cause of global warming

Energy BalancesEnergy Balances

AtmospherAtmospheric ic radiation radiation balancebalance

Surface Surface radiation radiation balancebalance

Surface Radiation BalanceSurface Radiation Balance Refers to 45% of insolation that Refers to 45% of insolation that

reaches the Earth’s surfacereaches the Earth’s surface Daily PatternDaily Pattern

Insolation peaks at noonInsolation peaks at noon varies seasonally, with maximum on the varies seasonally, with maximum on the

summer solsticesummer solstice Absorbing the insolation heats the Absorbing the insolation heats the

ground, which in turn heats the airground, which in turn heats the air Maximum air temperature reached between 3-Maximum air temperature reached between 3-

4 pm4 pm Minimum air temperature reached around Minimum air temperature reached around

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