1. 1

2. Focus Question 11.1
Distinguish between weather and climate. 2

3. Focus on the Atmosphere
Weather
Occurs over a short period of time
Constantly changing
Climate
Averaged over a long period of time
Generalized, composite of weather 3

4. Focus on the Atmosphere
Elements of weather and climate
Properties that are measured regularly:
Temperature
Humidity
Cloudiness
Precipitation
Air pressure
Wind speed and direction

5. Focus on the Atmosphere

6. Focus Question 11.1 Distinguish between weather and climate. Weather
Occurs over a short period of time
Constantly changing
Climate
Averaged over a long period of time
Composite of weather 6

7. Focus Question 11.2
What is ozone? Why is ozone important to life on Earth? 7

8. Composition of the Atmosphere
Air is a mixture of discrete gases
Major components of clean, dry air
78% Nitrogen (N)
21% Oxygen (O2)
Argon and other gases
0.036% Carbon dioxide (CO2)

9. Composition of the Atmosphere

10. Composition of the Atmosphere
Variable components of air
Water vapor
Up to 4% of air’s volume
Forms clouds and precipitation
Greenhouse gas
Aerosols
Tiny solid and liquid particles
Water vapor can condense on solids
Reflect sunlight
Color sunrise and sunset

11. Composition of the Atmosphere

12. Composition of the Atmosphere
Variable components of air
Ozone
Three atoms of oxygen (O3)
Distribution not uniform
Concentrated between 10 and 50 km above the surface
Absorbs harmful UV radiation
Human activity is depleting ozone by adding
Chlorofluorocarbons (CFCs)

13. Composition of the Atmosphere

14. Focus Question 11.2
What is ozone? Why is ozone important to life on Earth?
Three atoms of oxygen (O3)
Absorbs harmful UV radiation that negatively impacts life on Earth 14

15. Focus Question 11.3
What is the environmental lapse rate, and how is it determined? 15

16. Vertical Structure of the Atmosphere
Atmospheric pressure is the weight of the air above.
Average sea level pressure is 1000 millibars or psi
Pressure decreases with altitude
Half of atmosphere is below 3.5 mi (5.6 km)
90% of atmosphere is below 10 mi (16 km)

17. Vertical Structure of the Atmosphere

18. Vertical Structure of the Atmosphere
Atmospheric layers based on temperature
Troposphere
Bottom layer
Temperature decreases with altitude
Environmental lapse rate
Average 6.5˚C per km or 3.5˚F per 1000 feet
Thickness varies
Average height is about 12 km
Outer boundary is the tropopause

19. Vertical Structure of the Atmosphere

20. Vertical Structure of the Atmosphere
The environmental lapse rate is variable
Actual environmental lapse rate for any particular time and place
Measured with a radiosonde
Attached to a balloon and transmits data by radio

21. Vertical Structure of the Atmosphere

22. Vertical Structure of the Atmosphere
Stratosphere
12 to 50 km
Temperature increases at top
Outer boundary is the stratopause
Mesosphere
50 to 80 km
Temperature decreases
Outer boundary is the mesopause
Thermosphere
No well-defined upper limit
Fraction of atmosphere’s mass
Gases moving at high speeds

23. Vertical Structure of the Atmosphere

24. Focus Question 11.3
What is the environmental lapse rate, and how is it determined?
The environmental lapse rate is the temperature decrease in the troposphere
It is determined by measurement with a radiosonde 24

25. Focus Question 11.4 Briefly explain the primary cause of the seasons.25

26. Earth–Sun Relationships
Earth motions
Rotates on its axis
Revolves around the Sun
Seasons
Result of:
Changing Sun angle
Changing length of daylight

27. Earth–Sun Relationships

28. Earth–Sun Relationships
Seasons
Caused by Earth’s changing orientation to the Sun
Axis is inclined 23.5º
Axis is always pointed in the same direction

29. Earth–Sun Relationships
Special days (Northern Hemisphere)
Summer solstice: June 21–22
Sun’s vertical rays located at Tropic of Cancer
23.5º N latitude
Winter solstice: December 21–22
Sun’s vertical rays located at Tropic of Capricorn
23.5º S latitude
Autumnal equinox: September 22–23
Sun’s vertical rays located at equator (0º latitude)
Spring equinox: March 21–22

30. Earth–Sun Relationships

31. Focus Question 11.4 Briefly explain the primary cause of the seasons.
Earth’s changing orientation to the Sun
Changing Sun angle
Changing length of daylight 31

32. Focus Question 11.5
Distinguish between heat and temperature. 32

33. Energy, Heat, and Temperature
Heat is synonymous with thermal energy
Temperature refers to the intensity, or degree of "hotness"
Heat is always transferred from warmer to cooler objects
Mechanisms of heat transfer
Conduction
Molecular activity
Convection
Mass movement within a substance
Radiation (electromagnetic radiation)
Gamma waves, X-rays
Ultraviolet,visible, infrared
Microwaves and radio waves

34. Energy, Heat, and Temperature

35. Energy, Heat, and Temperature
Laws of Radiation
All objects emit radiant energy
Hotter objects radiate more total energy per unit area than colder objects
Hotter objects radiate more short-wavelength radiation than cooler objects
Good absorbers of radiation are good emitters as well

36. Energy, Heat, and Temperature

37. Focus Question 11.5 Distinguish between heat and temperature.
Heat refers to the quantity of energy present
Temperature is the degree of “hotness” 37

38. Focus Question 11.6
What factors cause albedo to vary from time to time and from place to place? 38

39. Heating the Atmosphere
Incoming solar radiation
Atmosphere is largely transparent to incoming solar radiation
Atmospheric effects
Reflection
Albedo (percent reflected)
Scattering
Absorption
Most visible radiation reaches the surface
About 50% absorbed at Earth’s surface

40. Heating the Atmosphere

41. Heating the Atmosphere

42. Heating the Atmosphere

43. Heating the Atmosphere
Radiation from Earth’s surface
Earth re-radiates longer wavelengths
Terrestrial radiation
Terrestrial radiation is absorbed by
Carbon dioxide and water vapor
Lower atmosphere is heated from Earth’s surface
Heating of the atmosphere is termed the greenhouse effect

44. Heating the Atmosphere

45. Focus Question 11.6
What factors cause albedo to vary from time to time and from place to place?
Amount of cloud cover and particulate matter
Angle of the Sun’s rays
Nature of Earth’s surface 45

46. Focus Question 11.7
Why has the CO2 level of the atmosphere been increasing for the past 200 years? 46

47. Human Impact on Global Climate
CO2 levels are rising
Industrialization of the past 200 years
Burning fossil fuels
coal, natural gas, and petroleum
Deforestation
Present CO2 level is 30% higher than its highest level over the past 650,000 years

48. Human Impact on Global Climate

49. Human Impact on Global Climate

50. Human Impact on Global Climate

51. Focus Question 11.7
Why has the CO2 level of the atmosphere been increasing for the past 200 years?
Industrialization
Burning fossil fuels
coal, natural gas, and petroleum
Deforestation 51

52. Human Impact?
How might the current climate change situation be different if humans had developed the steam engine instead of the gasoline engine? 52

53. For the Record: Air Temperature Data
Temperature measurement
Daily maximum and minimum
Other measurements
Daily mean temperature
Daily range
Monthly mean
Annual mean
Annual temperature range

54. For the Record: Air Temperature Data
Isotherms used to examine distribution of air temperatures over large areas
Line that connects points of the same temperature
iso = equal, therm = temperature

55. For the Record: Air Temperature Data

56. Focus Question 11.9
How can cloud cover influence the maximum temperature on an overcast day? 56

57. Why Temperatures Vary: The Controls of Temperature
Receipt of solar radiation
Other important controls
Differential heating of land and water
Land heats more rapidly than water
Land gets hotter than water
Land cools faster than water
Land gets cooler than water

58. Why Temperatures Vary: The Controls of Temperature

59. Why Temperatures Vary: The Controls of Temperature
Other important controls
Altitude
Geographic position
Cloud cover
Albedo

60. Why Temperatures Vary: The Controls of Temperature

61. Focus Question 11.9
How can cloud cover influence the maximum temperature on an overcast day?
Clouds reflect a significant portion of sunlight
Reducing amount of incoming solar radiation
Daytime temperatures will be lower 61

62. World Distribution of Temperature
Temperature maps
Temperatures are adjusted to sea level
January and July used for analysis
Represent temperature extremes

63. World Distribution of Temperature
Global temperature patterns
Temperature decreases poleward from tropics
Isotherms exhibit latitudinal shift with seasons
Warmest and coldest over land

64. World Distribution of Temperature

65. World Distribution of Temperature
Global temperature patterns
Southern Hemisphere
Isotherms are straighter
Isotherms are more stable
Isotherms show ocean currents
Annual temperature range
Small near equator
Increases with an increase in latitude
Greatest over continental locations