1 / 34

Appendix A

Appendix A. Length: m 1 km = 1000 m; 1 m = 100 cm = 1000 mm = 10 6 micrometer ( μ m) 1 inch (in.) = 2.54 cm 1 foot (ft) = 12 in. = 12*2.54 = 30.48 cm = 0.3048 m 1 mile (mi) = 1.61 km 1 nautical mile = 1.15 mi = 1.85 km. (b) Area: m 2 1 mi 2 = 1.61 2 km 2 = 2.59 km 2

Download Presentation

Appendix A

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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 = 30.48 cm = 0.3048 m • 1 mile (mi) = 1.61 km • 1 nautical mile = 1.15 mi = 1.85 km

  2. (b) Area: m2 • 1 mi2 = 1.612 km2= 2.59 km2 • Volume: m3 • 1 liter (l) = 1000 cm3 = 0.264 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 • 10-9 10-6 10-3 10-2 102 103 106 109

  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 = 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

  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-meaningfulcharacteristics: a zero point and a degree interval.

  11. 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 perspirationis an effective way to cool your body.

  13. 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 fluid (such as water and air) • Thermals • Soaring birds, like hawks and falcons, are highlyskilled 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 (.2-.29 μm) • ozone absorption • UV-B (.29-.32 μm) • runburn/skin cancer • UV-A (.32-.4 μm) • tan, skin cancer • Most sunscreen • reduces UV-B only Fig. 2-7, p. 32

  18. Radiation • electromagnetic spectrum • ultraviolet radiation (UV-A, B, C) • visible radiation (0.4-0.7 μm) shortwave (solar) radiation • infrared radiation longwave (terrestrial) radiation

  19. 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 tomelting 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: 0.6 desert: 0.3 grass: 0.2 forest: 0.15 water: 0.1

  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

  28. Fig. 2-16, p. 42

  29. 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. 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.

More Related