Appendix AAppendix A(a) Length: m

1 km = 1000 m; 1 m = 100 cm = 1000 mm = 106 micrometer (μm)

1 inch (in.) = 2.54 cm1 foot (ft) = 12 in. = 12*2.54 = 30.48 cm = 0.3048 m1 mile (mi) = 1.61 km1 nautical mile = 1.15 mi = 1.85 km

(b) Area: m2

1 mi2 = 1.612 km2 = 2.59 km2

(c) Volume: m3

1 liter (l) = 1000 cm3 = 0.264 gallon (gal) US

(d) Mass: kg

1 kg = 2.2 lb

(e) Speed: m/s

1 km/hr = 1000m/3600s = 0.28 m/s 1 mi/hr = 1609m/3600s = 0.45 m/s 1 knot = 1 nautical mile/hr = 1850m/3600s = 0.51m/s

(f) Force: newton (N) = kg m/s2

F = ma `a’ is acceleration (or change of speed with time) 1 dyne = 1 g cm/s2 =10-3 kg 10-2 m/s2 = 10-5 N

(g) Energy: joule (J) = Nm

E = FL `L’ is distance 1 J = 1 Nm = 0.24 Calorie (cal)

(h) Power: watt (W) = J/s

P = change of energy with time 1 horse power (hp) = 746 W

(i) Power of 10 10-9 10-6 10-3 10-2 102 103 106 109

(j) Pressure: pascal (Pa) = N/m2

P = F/Area 1 Pa = 1 N/m2 = 1 (kg m/s2)/m2 = 1 kg s-2 m-1

1 millibar (mb) = 100 Pa = 1 hecto Pa = 1 hPa

sea level surface pressure = 1013 mb

1 millimeter of mercury (mm Hg) = 1.33 mb because

Hg density = 13,546 kg/m3; earth’s gravity = 9.8 m/s2; Over unit area (m2), 1 mm Hg mass = 10-3 * 13,546 = 13.5 kg F = mg = 13.5 *9.8 N = 133 N P = F over unit area = 133 Pa = 1.33 mb

(k) Temperature: kelvin (K)

K = oC + 273; oC = 5/9 (oF -32) oF = 9/5 oC + 32

For instance 104 oF = 40 oC 20oC = 68 oF (Table A.1 on p. 437 could also be used)

Q: if temperature changes by 1 K, how much does it change in oC and oF? (A: 1 oC; 1.8oF)

Chapter 2: Chapter 2: Warming the Warming the Earth and the Earth and the AtmosphereAtmosphere Temperature and heat transferTemperature and heat transfer

Balancing act - absorption, Balancing act - absorption, emission and equilibriumemission and equilibrium

Incoming solar energyIncoming solar energy

Temperature and Temperature and Heat TransferHeat Transfer

Air T is a measureof the averagespeed of the Molecules

Warm less dense

Temperature ScalesTemperature Scales kinetic energy, temperature and heatkinetic energy, temperature and heat

K.E. = mvK.E. = mv22, Internal energy = C, Internal energy = CvvT, T,

Heat = energy transfer by conduction, Heat = energy transfer by conduction,

convection,and radiationconvection,and radiation Kelvin scale: SI unitKelvin scale: SI unit Celsius scale: Celsius scale: Fahrenheit scale: used for surface T in U.S.Fahrenheit scale: used for surface T in U.S. temperature conversionstemperature conversions

• Every temperature scale has two physically-meaningfulEvery temperature scale has two physically-meaningfulcharacteristics: a zero point and a degree interval.characteristics: a zero point and a degree interval.

Fig. 2-2, p. 27

Latent Heat - The Hidden Latent Heat - The Hidden WarmthWarmth

phase changes and energy exchangesphase changes and energy exchanges evaporation: faster molecules escape to air; slower evaporation: faster molecules escape to air; slower

molecules remain, leading to cooler water Tmolecules remain, leading to cooler water T

and reduced water energy; lost energy carriedand reduced water energy; lost energy carried

away by (or stored in) water vapor moleculesaway by (or stored in) water vapor molecules

Q: does the formation of clouds warm or cool the Q: does the formation of clouds warm or cool the

air in the clouds?air in the clouds?

sensible heat: sensible heat: we can feel and measurewe can feel and measure

• Latent heat explains why perspirationLatent heat explains why perspirationis an effective way to cool your body.is an effective way to cool your body.

Fig. 2-3, p. 28Stepped Art

ConductionConduction

Conduction: Conduction: heat transfer within a heat transfer within a

substance substance by molecule-to-molecule by molecule-to-molecule

contact due to T differencecontact due to T difference

good conductors:good conductors: metalsmetals

poor conductors:poor conductors: air (hot ground onlyair (hot ground only warms air withinwarms air within a few cm)a few cm)

ConvectionConvection

Convection: Convection: heat heat transfer by mass transfer by mass movement of a movement of a

fluid (such as water and fluid (such as water and air)air)

ThermalsThermals• Soaring birds, like hawks Soaring birds, like hawks and falcons, are highlyand falcons, are highly

skilled at finding thermals.skilled at finding thermals.

• Convection (vertical) vsConvection (vertical) vs Advection (horizontal)Advection (horizontal)

• Rising air expands and cools while Rising air expands and cools while sinking air warms by compressionsinking air warms by compression

RadiationRadiation Radiation: Radiation: energy transfer between objects by energy transfer between objects by

electromagnetic waves (without the space between them electromagnetic waves (without the space between them being necessarily heated);being necessarily heated);

packets of photons (particles) make up waves and groups of packets of photons (particles) make up waves and groups of waves make up a beam of radiation; waves make up a beam of radiation;

electromagnetic waveselectromagnetic waves Q: are molecules needed? Q: are molecules needed? In a vacuum, speed of light: 3*10In a vacuum, speed of light: 3*1055 km/s km/s

Wein’s lawWein’s law λλmaxmax = 2897 ( = 2897 (μμmK)/TmK)/T Stefan-Boltzmann lawStefan-Boltzmann law E = E = σσTT44

Fig. 2-7, p. 32

•All things emit radiation•Higher T leads to shorted λ•Higher T leads to higher E•Shorter λ photon carries more energy

•UV-C (.2-.29 μm)ozone absorption

•UV-B (.29-.32 μm)runburn/skin cancer

•UV-A (.32-.4 μm) tan, skin cancer

•Most sunscreenreduces UV-B only

RadiationRadiation

electromagnetic electromagnetic spectrumspectrum

ultraviolet radiation ultraviolet radiation (UV-A, B, C)(UV-A, B, C)

visible radiation visible radiation (0.4-(0.4-0.7 0.7 μμm)m)

shortwave (solar) radiationshortwave (solar) radiation

infrared radiationinfrared radiation

longwave (terrestrial)longwave (terrestrial)

radiationradiation

Fig. 2-8, p. 34

Balancing Act - Balancing Act - Absorption, Absorption,

Emission, and Emission, and EquilibriumEquilibrium

Selective Absorbers and Selective Absorbers and the Atmospheric the Atmospheric

Greenhouse EffectGreenhouse Effect blackbody radiationblackbody radiation perfect absorber; don’t haveperfect absorber; don’t have to be colored black;to be colored black; radiative equilibrium T = 255K;radiative equilibrium T = 255K; actual T = 288Kactual T = 288K selective absorbersselective absorbers snow: good absorber of infrared snow: good absorber of infrared

radiation, but not solar radiationradiation, but not solar radiation atmospheric greenhouse effectatmospheric greenhouse effect

• The best greenhouse gas is water The best greenhouse gas is water vapor, followed by COvapor, followed by CO22

Enhancement of the Enhancement of the Greenhouse EffectGreenhouse Effect

global warming: global warming: due to increase of COdue to increase of CO22, , CHCH44, and other greenhouse gases;, and other greenhouse gases;

global average T increased by 0.6 C in the past global average T increased by 0.6 C in the past 100 yr;100 yr;

expected to increase by 2-6 C at the end of 21expected to increase by 2-6 C at the end of 21stst centurycentury

positive and negative feedbackspositive and negative feedbacks• Positive feedback: increasing temperatures lead toPositive feedback: increasing temperatures lead to

melting of Arctic sea ice, which decreases the albedo.melting of Arctic sea ice, which decreases the albedo.• Positive water vapor-temperature feedbackPositive water vapor-temperature feedback• Potentially negative cloud-temperature feedback Potentially negative cloud-temperature feedback

Warming the Air from Warming the Air from BelowBelow

radiationradiation conductionconduction convectionconvection

• Fog “burns off” from the bottom up.Fog “burns off” from the bottom up.

Incoming Solar Incoming Solar EnergyEnergy

Scattered and Reflected Scattered and Reflected LightLight

Scattering: Scattering: blue sky, white sun, and red sunblue sky, white sun, and red sun Reflection: Reflection: more light is sent backwardsmore light is sent backwards Albedo:Albedo: ratio of reflected ratio of reflected over incoming over incoming radiation; radiation; fresh snow: 0.8fresh snow: 0.8 clouds: 0.6clouds: 0.6 desert: 0.3desert: 0.3 grass: 0.2grass: 0.2 forest: 0.15forest: 0.15 water: 0.1 water: 0.1

The Earth’s Annual The Earth’s Annual Energy BalanceEnergy Balance

What happens to the solar energy What happens to the solar energy that reaches the top of the earth’s that reaches the top of the earth’s atmosphere?atmosphere?

What happens to the solar energy What happens to the solar energy that is absorbed by the earth’s that is absorbed by the earth’s surface and by the atmosphere?surface and by the atmosphere?

Fig. 2-15, p. 41

Solar constant = 1367 W/m2

Fig. 2-16, p. 42

Fig. 2-17, p. 43

Why the Earth has Why the Earth has SeasonsSeasons

earth-sun distance: earth-sun distance: closer in wintercloser in winter

tilt of the earth’s axistilt of the earth’s axis

• Earth-sun Earth-sun distance has distance has little effect on little effect on atmospheric atmospheric temperature.temperature.

Seasons in the Northern Seasons in the Northern HemisphereHemisphere

insolationinsolation summer solsticesummer solstice spring and autumn equinoxspring and autumn equinox

Seasons in the Southern Seasons in the Southern HemisphereHemisphere

tilttilt solsticesolstice equinoxequinox

December 21 is the 1st day of winter in astronomical definitionnot in meteorological definition

Fig. 2-24, p. 50

Stepped Art

Local Seasonal Local Seasonal VariationsVariations

slope of hillsides: slope of hillsides: south-facing hills warmer south-facing hills warmer & drier& drier

vegetation differencesvegetation differences• Homes can exploit Homes can exploit

seasonal variations: seasonal variations: large windows large windows should face south.should face south.