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

Q: 10 μm = ? a) 10-5 m; b) 10-6 m; c) 10-7 m

(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

So 20 mi/gal = 20*1.6 km/(1/0.26) l ~ 8 km/l

(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 earth’s gravity: g = 9.8 m/s2

(g) Energy (heat, work): joule (J) = Nm E = FL `L’ is distance 1 J = 1 Nm = 0.24 Calorie (cal)

1 cal = heat needed to raise temperature from 14.5oC to 15.5oC of 1 cm3 of water (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

Q: The work from lifting weight of 50 kg for 0.3 m is a) 1.5 J; b) 15 J; c) 150 J; d) 1500 J

(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

Q: surface pressure 1013 mb = ? a) 500 mmHg; b) 760 mmHg; c) 1000 mmHg

(k) Temperature: kelvin (K)

K = oC + 273; oC = 5/9 (oF -32) oF = 9/5 oC + 32 (Table A.1 on p. 437 could also be used)

Q: 104 oF = ? a) 20 oC; b) 30 oC; c) 40 oC Q: if temperature changes by 1 oC, how much does it change in oF? a) 5/9 oF; b) 1 oF; c) 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 moleculeaway by (or stored in) water vapor molecule

sensible heat: sensible heat: we can feel and measurewe can feel and measure Q: Cloud formation [a) warms; b) cools; c) does not Q: Cloud formation [a) warms; b) cools; c) does not

change the change the temperature of] the atmosphere?temperature of] the atmosphere?

• 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)

Q: why does the rising air expands Q: why does the rising air expands and cools?and cools?

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

electromagnetic waveselectromagnetic waves 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

Q: In a vacuum, there is still

a) Conduction only; b) convection only; c) radiation only; d) all of them

Fig. 2-7, p. 32

•All things emit radiation•Higher T leads to shorter 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)sunburn/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 - Absorption, Balancing Act - Absorption, Emission, and EquilibriumEmission, and Equilibrium

Without atmosphere, the earth average temperature is -18 oC due to the balance of solar heating of half of the earth and longwave radiation loss from the earth surface

With atmosphere, the earth surface temperature is 15 oC due to the selective absorption of the atmosphere

In other words, the 33 oC difference is caused by the atmospheric green house effect

Selective AbsorbersSelective Absorbers in general, earth’s surface is nearlyin general, earth’s surface is nearly black for infrared radiationblack for infrared radiation

In particular, snow is good absorber of In particular, snow is good absorber of infrared radiation, but not solar infrared radiation, but not solar radiationradiation

Atmospheric window: 8-12 Atmospheric window: 8-12 μμmm

The best greenhouse gas in the The best greenhouse gas in the atmosphere is water vapor, atmosphere is water vapor, followed by CO2followed by CO2 Low-level clouds are also good Low-level clouds are also good

absorbers of longwave radiation (and absorbers of longwave radiation (and hence increase air temperature at hence increase air temperature at night) night)

Enhancement of the Enhancement of the Greenhouse EffectGreenhouse Effect

global warming:global warming: due to increase of COdue to increase of CO22, CH, CH44, and other , and other greenhouse gases;greenhouse gases;

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

expected to increase by 2-6 expected to increase by 2-6 ooC at the end of 21C at the end of 21stst century century positive and negative feedbackspositive and negative feedbacks

• Positive snow feedback: a) increasing temperatures lead toPositive snow feedback: a) increasing temperatures lead tomelting of snow/ice; b) this decreases surface albedo and increases melting of snow/ice; b) this decreases surface albedo and increases surface absorption of solar radiation; c) this increases temperaturesurface absorption of solar radiation; c) this increases temperature

• Potentially negative cloud-temperature feedbackPotentially negative cloud-temperature feedback

Q: What is the water vapor-temperature feedback?Answer: 1) increasing air temperature; 2) increasing evaporation; 3) increasing water vapor in the air; 4) water vapor is an atmospheric

greenhouse gas; 5) increasing air temperature; 6) positive feedback

Warming the Air from Warming the Air from BelowBelow

Radiation: Radiation: heat the groundheat the ground Conduction: Conduction: transport heat upward within 1 few cm of groundtransport heat upward within 1 few cm of ground Convection: Convection: transport heat upward within ~1 km of groundtransport heat upward within ~1 km of ground

Only under special conditions, can air moves above ~1 km height and form clouds.

Q: How high can air parcel move up in Tucson in summer afternoon in general?a) 1 km; b) 3 km; c) 5

km

Incoming Solar EnergyIncoming Solar EnergyLight scattering: light deflected in all directions (forward, sideward, and backward), called diffuse light, by air molecules and aerosols.

Q: Why is the sky blue? Answer: 1) because air molecules are much smaller than the wavelength of visible light, they are most effective scatterers of the shorter (blue) than the longer (red) wavelengths; 2) diffuse light is primarily blue

Q: why is the sun perceived as white at noon? A: because all wavelengths of visible lights strike our eyes

Q: Why is the sun red at sunset?A: 1) atmosphere is thick;2) shorter wavelengths arescattered and only red lightreaches our eyes

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 over incoming radiationratio of reflected over incoming 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: 0.1water: 0.1

The Earth’s Annual Energy The Earth’s Annual Energy BalanceBalance

Q: What happens to the solar energy at top of the earth’s Q: What happens to the solar energy at top of the earth’s atmosphere, in the atmosphere, and at surface? A: next slideatmosphere, in the atmosphere, and at surface? A: next slide

Q: Most solar energy on average is:a) absorbed by surface; b) absorbed by atmosphere;c) reflected and scattered to the space

Q: What is the energy balance at top of the atmosphere, in Q: What is the energy balance at top of the atmosphere, in the atmosphere, and at surface? A: see slidethe atmosphere, and at surface? A: see slide

Q: top: 100 (solar) = 30 (reflection) + 70 (longwave)Q: top: 100 (solar) = 30 (reflection) + 70 (longwave) surface: 51 (solar) = 7 (convection) + 23 (evap) + 21 surface: 51 (solar) = 7 (convection) + 23 (evap) + 21

(net longwave)(net longwave) air: 7 (conv) + 23 (evap)+ 19 (solar) = 49 (net longwave)air: 7 (conv) + 23 (evap)+ 19 (solar) = 49 (net longwave)

Fig. 2-15, p. 41

Solar constant = 1367 W/m2

Fig. 2-16, p. 42

Fig. 2-17, p. 43

Heat is transferred by both atmosphere and oceanQ: What is the fundamental driving force of wind patterns in the atmosphere? A: differential heating

Why the Earth has SeasonsWhy the Earth has Seasons earth-sun distanceearth-sun distance: : closer in wintercloser in winter tilt of the earth’s axistilt of the earth’s axis

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

Q: if the earth’s axis were NOT tilted, would we still have seasons?

a) yes; b) no

Q: will sun set at 70oN on June 21?

a) yes; b) no

Seasons in the Northern Seasons in the Northern HemisphereHemisphere

Factors determining surface heating by solar energy: 1) solar angle; 2) time length from sunrise to sunset.

Q: why is Arizona warmer in summer than northern Alaska where sun shines for 24 hours (see figure)? A: sun angle is too low in Alaska so that 1) solar insolation (i.e., incoming solar radiation) per unit area is too small, and 2) atmospheric path for solar rays is much longer and most of the solar energy is scattered, reflected, or absorbed by the atmosphere

Q: Why is temperature higher at 40oN on June 21 than on Dec 21?a) longer daytime; b) higher solar angle;

c) both a) and b)

Fig. 2-24, p. 50

Stepped ArtQ: In Tucson summer, the sun rises from: a) northeast; b) nearly east; c) southeast

Local Seasonal Local Seasonal VariationsVariations

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

vegetation differencesvegetation differencesQ: Without considering views, Q: Without considering views,

should Tucson homes have should Tucson homes have large windows facing large windows facing a) south; b) north?a) south; b) north?

Q: What would be the answer Q: What would be the answer for a North Dakota home?for a North Dakota home?

a) south; b) northa) south; b) north