Appendix A (a)Length: m 1 km = 1000 m; 1 m = 100 cm = 1000 mm = 10 6 micrometer (μm) 1 inch (in.) = 2.54 cm 1 foot (ft) = 12 in. = 12*2.54 = cm = m 1 mile (mi) = 1.61 km 1 nautical mile = 1.15 mi = 1.85 km Q: 10 μm = ? a) m; b) m; c) m

(b) Area: m 2 1 mi 2 = km 2 = 2.59 km 2 (c)Volume: m 3 1 liter (l) = 1000 cm 3 = 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/s 2 F = ma `a’ is acceleration (or change of speed with time) 1 dyne = 1 g cm/s 2 =10 -3 kg m/s 2 = N earth’s gravity: g = 9.8 m/s 2

(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 14.5 o C to 15.5 o C 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 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/m 2 P = F/Area 1 Pa = 1 N/m 2 = 1 (kg m/s 2 )/m 2 = 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/m 3 ; earth’s gravity = 9.8 m/s 2 ; Over unit area (m 2 ), 1 mm Hg mass = * 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 = o C + 273; o C = 5/9 ( o F -32) o F = 9/5 o C + 32 (Table A.1 on p. 437 could also be used) Q: 104 o F = ? a) 20 o C; b) 30 o C; c) 40 o C Q: if temperature changes by 1 o C, how much does it change in o F? a) 5/9 o F; b) 1 o F; c) 1.8 o F

Chapter 2: Warming the Earth and the Atmosphere Temperature and heat transfer Temperature and heat transfer Balancing act - absorption, emission and equilibrium Balancing act - absorption, emission and equilibrium Incoming solar energy Incoming solar energy

Temperature and Heat Transfer Air T is a measure of the average speed of the Molecules Warm less dense

Temperature Scales kinetic energy, temperature and heat kinetic energy, temperature and heat K.E. = mv 2, Internal energy = C v T, K.E. = mv 2, Internal energy = C v T, Heat = energy transfer by conduction, Heat = energy transfer by conduction, convection,and radiation convection,and radiation Kelvin scale: SI unit Kelvin 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 conversions temperature conversions Every temperature scale has two physically-meaningful characteristics: a zero point and a degree interval.Every temperature scale has two physically-meaningful characteristics: a zero point and a degree interval.

Fig. 2-2, p. 27

Latent Heat - The Hidden Warmth phase changes and energy exchanges phase changes and energy exchanges evaporation: faster molecules escape to air; slower evaporation: faster molecules escape to air; slower molecules remain, leading to cooler water T molecules remain, leading to cooler water T and reduced water energy; lost energy carried and reduced water energy; lost energy carried away by (or stored in) water vapor molecule away by (or stored in) water vapor molecule sensible heat: we can feel and measure sensible heat: we can feel and measure Q: Cloud formation [a) warms; b) cools; c) does not change the Q: Cloud formation [a) warms; b) cools; c) does not change the temperature of] the atmosphere? temperature of] the atmosphere? Latent heat explains why perspiration is an effective way to cool your body.Latent heat explains why perspiration is an effective way to cool your body.

Fig. 2-3, p. 28 Stepped Art

Conduction Conduction Conduction: Conduction: heat transfer within a substance heat transfer within a substance by molecule-to-molecule contact due to T difference by molecule-to-molecule contact due to T difference good conductors: good conductors: metals metals poor conductors: poor conductors: air (hot ground only air (hot ground only warms air within warms air within a few cm) a few cm)

Convection Convection: heat transfer by mass movement of a Convection: heat transfer by mass movement of a fluid (such as water and air) fluid (such as water and air) Thermals Thermals Soaring birds, like hawksSoaring birds, like hawks and falcons, are highly skilled at finding thermals. and falcons, are highly skilled at finding thermals. Convection (vertical) vsConvection (vertical) vs Advection (horizontal) Advection (horizontal) Q: why does the rising air expands and cools? and cools?

Radiation Radiation: energy transfer between objects by electromagnetic waves (without the space between them being necessarily heated); Radiation: energy transfer between objects by electromagnetic waves (without the space between them being necessarily heated); packets of photons (particles) make up waves and groups of waves make up a beam of radiation; packets of photons (particles) make up waves and groups of waves make up a beam of radiation; electromagnetic waves electromagnetic waves In a vacuum, speed of light: 3*10 5 km/s In a vacuum, speed of light: 3*10 5 km/s Wein’s law Wein’s law λ max = 2897 (μmK)/T λ max = 2897 (μmK)/T Stefan-Boltzmann law Stefan-Boltzmann law E = σT 4 E = σT 4 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 ( μm) ozone absorption UV-B ( μm) sunburn/skin cancer UV-A ( μm) tan, skin cancer Most sunscreen reduces UV-B only

Radiation electromagnetic spectrum electromagnetic spectrum ultraviolet radiation (UV-A, B, C) ultraviolet radiation (UV-A, B, C) visible radiation ( μm) visible radiation ( μm) shortwave (solar) radiation shortwave (solar) radiation infrared radiation infrared radiation longwave (terrestrial) longwave (terrestrial) radiation radiation

Fig. 2-8, p. 34

Balancing Act - Absorption, Emission, and Equilibrium Without atmosphere, the earth average temperature is -18 o C 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 o C due to the selective absorption of the atmosphere In other words, the 33 o C difference is caused by the atmospheric green house effect

Selective Absorbers in general, earth’s surface is nearly in general, earth’s surface is nearly black for infrared radiation black for infrared radiation In particular, snow is good absorber of infrared radiation, but not solar radiation In particular, snow is good absorber of infrared radiation, but not solar radiation Atmospheric window: 8-12 μm Atmospheric window: 8-12 μm The best greenhouse gas in the The best greenhouse gas in the atmosphere is water vapor, atmosphere is water vapor, followed by CO2 followed by CO2 Low-level clouds are also good absorbers of longwave radiation (and hence increase air temperature at night) Low-level clouds are also good absorbers of longwave radiation (and hence increase air temperature at night)

Enhancement of the Greenhouse Effect global warming: due to increase of CO 2, CH 4, and other greenhouse gases; global warming: due to increase of CO 2, CH 4, and other greenhouse gases; global average T increased by 0.6 o C in the past 100 yr; global average T increased by 0.6 o C in the past 100 yr; expected to increase by 2-6 o C at the end of 21 st century expected to increase by 2-6 o C at the end of 21 st century positive and negative feedbacks positive and negative feedbacks Positive snow feedback: a) increasing temperatures lead to melting of snow/ice; b) this decreases surface albedo and increases surface absorption of solar radiation; c) this increases temperaturePositive snow feedback: a) increasing temperatures lead to melting of snow/ice; b) this decreases surface albedo and increases surface 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 Below Radiation: heat the ground Radiation: heat the ground Conduction: transport heat upward within 1 few cm of ground Conduction: transport heat upward within 1 few cm of ground Convection: transport heat upward within ~1 km of ground Convection: transport 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 Energy Light 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 are scattered and only red light reaches our eyes

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

The Earth’s Annual Energy Balance Q: What happens to the solar energy at top of the earth’s atmosphere, 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 the atmosphere, and at surface? A: see slide Q: top: 100 (solar) = 30 (reflection) + 70 (longwave) surface: 51 (solar) = 7 (convection) + 23 (evap) + 21 (net longwave) surface: 51 (solar) = 7 (convection) + 23 (evap) + 21 (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/m 2

Fig. 2-16, p. 42

Fig. 2-17, p. 43 Heat is transferred by both atmosphere and ocean Q: What is the fundamental driving force of wind patterns in the atmosphere? A: differential heating

Why the Earth has Seasons earth-sun distance : closer in winter earth-sun distance : closer in winter tilt of the earth’s axis tilt 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 70 o N on June 21? a) yes; b) no

Seasons in the Northern Hemisphere 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 40 o N 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 Art Q: In Tucson summer, the sun rises from: a) northeast; b) nearly east; c) southeast

Local Seasonal Variations slope of hillsides: south-facing hills warmer & drier slope of hillsides: south-facing hills warmer & drier vegetation differences vegetation differences Q: Without considering views, should Tucson homes have large windows facing a) south; b) north? Q: What would be the answer for a North Dakota home? a) south; b) north a) south; b) north