SECTION 4.1 – INTRODUCTION
The two factors that control the amount of solar radiation that a unit area (m²)
receives at the outer edge of the atmosphere, and eventually the Earth’s surface, are
the Sun’s intensity and its duration.
1. Briefly define solar intensity and duration. [2 pt]
Intensity of solar radiation:
Duration of solar radiation:
2. On the June Solstice (June 21), which location (latitude) would have the greatest
intensity of solar radiation? Which location (latitude) would have the greatest
duration of solar radiation? (Hint: Use your knowledge on Earth-Sun relationships for guidance) [2 pt]
3. Complete Table 1 by calculating the angle that the noon sun (NSA) would strike
the Earth at each of the indicated latitudes on the specified date. Approximately, how
many hours of daylight would each place experience on these dates? Calculate the
beam intensity of the insolation on each date. (Hint: Again, use your knowledge on
Earth-Sun relationships (Lab 2) for guidance) [18 pt]
Table 1. Noon sun angle (NSA), length of day and beam intensity.
March 21 June 21
NSA (°)
Length
of Day
(hrs)
Beam
Intensity
(%)
NSA (°)
Length
of Day
(hrs)
Beam
Intensity
(%)
60°N
0°
30°S
4. Explain the reason why the intensity and duration of solar radiation received on
Earth is not constant at any particular latitude throughout the year. [2 pt]
SECTION 4.2 – ATMOSPHERIC AND SURFACE HEATING
Figure 1 illustrates the atmospheric effects on incoming solar radiation for an
average noon sun angle. Answer questions 6-9 by examining the figure.
Figure 1. Solar radiation budget of the atmosphere and Earth.
5. _______ percent of the incoming solar radiation is reflected and scattered back to
space. [1 pt]
6. _______ percent of the incoming solar radiation is absorbed by gases in the
atmosphere and clouds. [1 pt]
7. _______ percent of the incoming solar radiation is absorbed at the Earth’s surface.[1 pt]
8. (Two and a half, Four) times as much incoming radiation is absorbed by Earth’s
surface than by the atmosphere and clouds. Circle the correct answer. [1 pt]
Figure 2 illustrates the effects of the atmosphere on various wavelengths of
radiation. Recall from the previous lab using Wien’s law and the calculations and
conclusions from that exercise. Use Figure 2 to answer questions 9-13 by circling the
correct response.
9. The incoming solar radiation that passes through the atmosphere and is absorbed
at the Earth’s surface is primarily in the form of (ultraviolet, visible, infrared)
wavelengths. [1 pt]
10. When the surface of Earth re-emits the solar energy it has absorbed, the
outgoing terrestrial radiation is primarily (ultraviolet, visible, infrared) wavelengths.
[1 pt]
11. (Ultraviolet, Visible, Infrared) wavelengths of radiation are absorbed efficiently
by oxygen and ozone in the atmosphere. [1 pt]
12. (Nitrogen, Carbon dioxide) and (water vapor, ozone) are the two principal gases
that absorb most of the terrestrial radiation in the atmosphere. [2 pt]
13. (Carbon dioxide, ozone) and (oxygen, water vapor) exclusively account for all
the total atmosphere absorption between 0.1 and 0.3μm. [2 pt]
Assume Figure 1 represents the atmospheric effects on incoming solar radiation for
an average noon sun angle of 50°. Answer questions 14-17 concerning other sun
angles by circling the appropriate responses.
14. If the noon sun angle is 90°, solar radiation would have to penetrate a (greater,
lesser) thickness of atmosphere than with an average noon sun angle. [1 pt]
15. The result of a 90° noon sun angle would be that (more, less) incoming solar
radiation would be reflected, scattered and absorbed by the atmosphere and (more,
less) radiation would be absorbed and reradiated by the Earth’s surface to heat the
atmosphere. [2 pt]
16. If the noon sun angle is 20°, solar radiation would have to penetrate a (greater,
lesser) thickness of atmosphere than with an average noon sun angle. [1 pt]
17. The result of a 20° noon sun angle would be that (more, less) incoming solar
radiation would be reflected, scattered and absorbed by the atmosphere and (more,
less) radiation would be absorbed and reradiated by the Earth’s surface to heat the
atmosphere. [2 pt]
18. How is the angle at which a solar beam strikes Earth’s surface related to the
quantity of solar radiation received by each square meter of area. [1 pt]
19. How is the length of daylight related to the quantity of solar radiation received
by each square meter of area at the surface? [1 pt]
Figure 3 presents the annual temperature curves for two cities (A and B) that are
located in North America at approximately 37°N latitude. On any date, both cities
receive the same intensity and duration of solar radiation. One city is in the center of
the continent while the other is on the coast. Use Figure 3 to answer questions 20-
27. Circle your answer.
20. In Figure 3, city (A, B) has the highest mean monthly temperature. [1 pt]
21. City (A, B) has the lowest mean monthly temperature. [1 pt]
22. The greatest annual temperature range (difference between highest and lowest
mean monthly temperatures) occurs at city (A, B). [1 pt]
23. City (A, B) reaches its maximum mean monthly temperature at an earlier date.
[1 pt]
24. City (A, B) maintains a more uniform temperature throughout the year. [1 pt]
25. City A is most likely located (along a coast, in the center of a continent). [1 pt]
26. The most likely location for city B is (coastal, mid-continent). [1 pt]
27. Describe the effect that the location, along the coast or in the center of a
continent, has on the annual temperature pattern of a city. [2 pt]
Questions 28-35 refer to Figure 4, the daily temperature graph for a mid-latitude city
on a sunny summer. Complete each question by filling in the correct response.
28. The coolest temperature of the day occurs at _________________________. [1 pt]
29. The warmest temperature of the days occurs at _________________________. [1 pt]
30. What is the daily temperature range (difference between maximum and
minimum temperatures for the day)? [2 pt]
Daily temperature range: ______________°F (______________°C)
31. What is the daily temperature mean (average of the maximum and minimum
temperatures)? [2 pt]
Daily temperature mean: ______________°F (______________°C)
32. Recall the mechanisms for heating the atmosphere. Why does the warmest daily
temperature occur in the mid-to-late afternoon rather than at the time of the highest
sun angle? [2 pt]
33. Why does the coolest temperature of the day occur at about sunrise? [1 pt]
34. How would clouds influence daily maximum and minimum temperatures? [1 pt]
35. On Figure 4, sketch and label a colored line that would best represent a daily
graph for a typical cloudy day. [1 pt]
Questions 36-48 refer to Figure 6 which shows the World Distribution of Mean
Surface Temperatures (°C) for January and July. Circle and/or fill in the correct
answer when required.
37. In general, how do surface temperatures vary from the equator toward the
poles? Why does this variation occur? [2 pt]
38. During January and July, the warmest and coldest temperatures occur over
which countries and/or oceans? [2 pt]
Warmest global temperatures: ______________________________________________
Coldest global temperatures: _______________________________________________
39. During January and July, the locations of the warmest and coldest global
temperatures are over (land, water). [1 pt]
Figure 6. World Distribution of Mean Surface Temperatures (°C) for January
and July.
40. Calculate the annual temperature range at each of the following locations. You
may need to use an atlas or online site to find these locations. [6 pt]
Coastal Norway at 60°N: _____________°C (_____________°F)
Siberia at 60°N, 120°E: _____________°C (_____________°F)
Equator over the central Atlantic Ocean: _____________°C (_____________°F)
41. Contrast the annual temperature range at coastal Norway and Siberia. Why do
each exhibit such different ranges though they sit on the same latitude? [3 pt]
42. Why is temperature relatively uniform throughout the year in the tropics? [2 pt]
43. Using the two maps in Figure 6, calculate the approximate average annual
temperature range for Boston, MA. [2 pt]
Average annual temperature range: _____________°C (_____________°F)
44. Which global location from question 40 has a range most like that calculated for
Boston? Explain. [2 pt]
45. Trace the path of the 5°C isotherm over North America in January. Explain why
the isotherm deviates from a true east-west orientation where it crosses the Pacific
Ocean onto the North American continent. [2 pt]
46. Trace the path of the 20°C isotherm over North America in July. Explain why the
isotherm deviates from a true east-west orientation where it crosses from the Pacific
Ocean onto the continent. [2 pt]
47. Why do the isotherms in the Southern Hemisphere follow a true east-west
orientation more closely than those in the Northern Hemisphere? [2 pt]
48. Why does the entire pattern of isotherms shift northward between the January
and July maps? [2 pt]
Use Figure 7 to answer questions 49-56.
49. Using the temperature as a guide, label the mesosphere, stratosphere,
troposphere and thermosphere on the temperature profile shown in Figure 7. [4 pt]
50. On Figure 7, draw a line and label the tropopause, mesopause and stratopause.
[3 pt]
Figure 7. Atmospheric temperature profile.
51. What is the approximate temperature of the atmosphere at each of the following
altitudes? [6 pt]
10 km: _____________°C (_____________°F)
45 km: _____________°C (_____________°F)
80 km: _____________°C (_____________°F)
52. Using Figure 7, calculate the average decrease in temperature with altitude of
the troposphere in both °C/km and °F/mi. [2 pt]
_____________°C/km (_____________°F/mi)
53. Explain why temperature decreases with altitude in the troposphere. [2 pt]
54. Explain why temperature increases with altitude in the stratosphere. [2 pt]
55. Explain why temperature increases with altitude in the thermosphere. [2 pt]
56. Explain the role of ozone in the stratosphere. What will be the effect on radiation
at the Earth’s surface if there is a decrease of ozone in the stratosphere? [2 pt]
Assume the average, or normal, environmental lapse rate (temperature decrease
with altitude) in the troposphere is 3.5°F per 1,000ft (6.5°C per km)
57. If the surface temperature is 50°F (10°C), what would be the approximate
temperature at 45,000 feet (13,716 meters)? [2 pt]
_____________°F (_____________°C)
58. If the surface temperature is 65°F (18°C), at approximately what altitude would
a pilot expect to find each of the following atmospheric temperatures? [4 pt]
20°F: _____________ feet (-6.67°C: _____________ meters)
0°C: _____________ meters (32°F: _____________ feet)
59. Which two layers of the atmosphere exhibit temperature inversions? [2 pt]
60. Suggest a possible cause for a surface temperature inversion. [2 pt]
SECTION 4.3 – WINDCHILL EQUIVALENT TEMPERATURE
61. Refer to Figure 8, the chart diagramming windchill equivalent temperatures.
What is the windchill equivalent temperature sensed by the human body in the
following situations? [3 pt]
Air Temperature (°F) Wind Speed (mph) Windchill Equivalent
Temperature (°F)
5° 5
-20° 55
-35° 30
62. If the air temperature is -20°F and the current wind speed is 40mph, how long
before frostbite sets in? [1 pt]
63. If the windchill equivalent temperature is -48°F and the wind speed is 35mph,
what is the actual air temperature? Under these conditions, how soon before
frostbite sets in? [2 pt]
64. If the actual air temperature is 10°F, what wind speed would give you a windchill
equivalent temperature of -19°F? Under these conditions, how soon before frostbite
sets in? [2 pt]
65. If the wind speed maintains a sustained speed over a 24-hour period (12am to
12am), when do you believe the lowest windchill equivalent temperature would be
experienced? Why? [2 pt]
66. Write a brief summary of the effect of wind speed on how long a person can be
exposed to the elements before frostbite develops. Use Figure 8 and the previous
questions for guidance. [2 pt]
