1. Appendix A Length: m 1 km = 1000 m;
1 m = 100 cm = 1000 mm = 106 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

2. (b) Area: m2
1 mi2 = km2 = 2.59 km2
Volume: m3
1 liter (l) = 1000 cm3 = gallon (gal) US
(d) Mass: kg
1 kg = 2.2 lb

3. (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

4. (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
Power of 10

5. 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

6. 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 = * 13,546
= 13.5 kg
F = mg = 13.5 *9.8 N = 133 N
P = F over unit area = 133 Pa = 1.33 mb

7. (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)

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

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

10. Temperature Scales kinetic energy, temperature and heat
K.E. = mv2, Internal energy = CvT,
Heat = energy transfer by conduction,
convection,and radiation
Kelvin scale: SI unit
Celsius scale:
Fahrenheit scale: used for surface T in U.S.
temperature conversions
Every temperature scale has two physically-meaningful characteristics: a zero point and a degree interval.

11. Figure 2.2: Comparison of Kelvin, Celsius, and Fahrenheit scales.
Fig. 2-2, p. 27

12. Latent Heat - The Hidden Warmth
phase changes and energy exchanges
evaporation: faster molecules escape to air; slower
molecules remain, leading to cooler water T
and reduced water energy; lost energy carried
away by (or stored in) water vapor molecules
Q: does the formation of clouds warm or cool the
air in the clouds?
sensible heat: we can feel and measure
Latent heat explains why perspiration is an effective way to cool your body.

13. Figure 2.3: Heat energy absorbed and released.
Stepped Art
Fig. 2-3, p. 28

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

15. Convection Convection: heat transfer by mass movement of a Thermals
fluid (such as water and air)
Thermals
Soaring birds, like hawks
and falcons, are highly skilled at finding thermals.
Convection (vertical) vs
Advection (horizontal)
Rising air expands and cools while
sinking air warms by compression

16. Radiation
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;
electromagnetic waves
Q: are molecules needed?
In a vacuum, speed of light: 3*105 km/s
Wein’s law
λmax = 2897 (μmK)/T
Stefan-Boltzmann law
E = σT4

17. All things emit radiation Higher T leads to shorted λ
Higher T leads to higher E
Shorter λ photon carries more energy
UV-C ( μm)
ozone absorption
UV-B ( μm)
runburn/skin cancer
UV-A ( μm)
tan, skin cancer
Most sunscreen
reduces UV-B only
Figure 2.7: Radiation characterized according to wavelength. As the wavelength decreases, the energy carried per wave increases.
Fig. 2-7, p. 32

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

19. Figure 2.8: The sun’s electromagnetic spectrum and some of the descriptive names of each region. The numbers underneath the curve approximate the percent of energy the sun radiates in various regions.
Fig. 2-8, p. 34

20. Balancing Act - Absorption, Emission, and Equilibrium

21. Selective Absorbers and the Atmospheric Greenhouse Effect
blackbody radiation
perfect absorber; don’t have
to be colored black;
radiative equilibrium T = 255K;
actual T = 288K
selective absorbers
snow: good absorber of infrared
radiation, but not solar radiation
atmospheric greenhouse effect
The best greenhouse gas is water vapor, followed by CO2

22. Enhancement of the Greenhouse Effect
global warming: due to increase of CO2, CH4, and other greenhouse gases;
global average T increased by 0.6 C in the past 100 yr;
expected to increase by 2-6 C at the end of 21st century
positive and negative feedbacks
Positive feedback: increasing temperatures lead to melting of Arctic sea ice, which decreases the albedo.
Positive water vapor-temperature feedback
Potentially negative cloud-temperature feedback

23. Warming the Air from Below
radiation
conduction
convection
Fog “burns off” from the bottom up.

24. Incoming Solar Energy

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

26. The Earth’s Annual Energy Balance
What happens to the solar energy that reaches the top of the earth’s atmosphere?
What happens to the solar energy that is absorbed by the earth’s surface and by the atmosphere?

27. Solar constant = 1367 W/m2 Fig. 2-15, p. 41
Figure 2.15: On the average, of all the solar energy that reaches the earth’s atmosphere annually, about 30 percent (30⁄100) is reflected and scattered back to space, giving the earth and its atmosphere an albedo of 30 percent. Of the remaining solar energy, about 19 percent is absorbed by the atmosphere and clouds, and 51 percent is absorbed at the surface.
Fig. 2-15, p. 41

28. Figure 2. 16: The earth-atmosphere energy balance
Figure 2.16: The earth-atmosphere energy balance. Numbers represent approximations based on surface observations and satellite data. While the actual value of each process may vary by several percent, it is the relative size of the numbers that is important.
Fig. 2-16, p. 42

29. Figure 2.17: The average annual incoming solar radiation (red line) absorbed by the earth and the atmosphere along with the average annual infrared radiation (blue line) emitted by the earth and the atmosphere.
Fig. 2-17, p. 43

30. Why the Earth has Seasons
earth-sun distance: closer in winter
tilt of the earth’s axis
Earth-sun distance has little effect on atmospheric temperature.

31. Seasons in the Northern Hemisphere
insolation
summer solstice
spring and autumn equinox

32. Seasons in the Southern Hemisphere
tilt
solstice
equinox
December 21 is the 1st day of
winter in astronomical definition
not in meteorological definition

33. Figure 2.24: The apparent path of the sun across the sky as observed at different latitudes on the June solstice (June 21), the December solstice (December 21), and the equinox (March 20 and September 22).
Stepped Art
Fig. 2-24, p. 50

34. Local Seasonal Variations
slope of hillsides: south-facing hills warmer & drier
vegetation differences
Homes can exploit seasonal variations: large windows should face south.