CLIMATE
INTRODUCTION
This lab will introduce you to the basic elements of climate and climate classification, including the
presentation and analysis of climate data as well as the spatial distribution of climates around the world and
the United States.
EARTH’S CLIMATES
Weather is the condition of the atmosphere at a given time and place while climate is the variability of
weather over time, including the timing, averages, variance and extremes of temperature and precipitations.
"Climate is what you expect, weather is what you get" - Robert A. Heinlein
The study of Earth's climates is called climatology. Basic components of climate can be summarized for a
location using a figure called a climograph.
Many measures describing the state of the atmosphere can be used to classify climates: daily net radiation,
atmospheric pressure, wind speed and direction, cloud cover and type, presence/absence of fog,
precipitations type and intensity, incidence of cyclones and anticyclones, frequency of frontal passages.
However, most classifications are based on temperature and precipitations (average monthly values and
annual variations) because detailed observations including all the elements listed above are not made
everywhere on a daily basis.
To study climates from a global viewpoint, climatologists classify air temperature and precipitations values
into distinctive climate types. This requires developing a set of rules to examine average monthly
temperature and precipitations variability to determine the climate type of a station.
TEMPERATURE
The annual variation in insolation provides the basic control on global temperature patterns. On a regional
scale, temperature will be affected by the maritime/continentality effect and/or altitude. For example, coastal
locations will show a small annual range in temperature while continental locations will show a large range.
This will lead to different types of annual temperature cycles related to latitude and location.
Air temperature also has an important effect on precipitations: warm air can hold more moisture than cold
air. Thus, colder climates generally have lower precipitations than warmer climates.
PRECIPITATIONS
Total annual precipitations is a useful quantity in establishing the character of a climate type, but you also
have to take into account the seasonality of precipitations. Precipitations will tend to be greater during the
warmer months of the temperature cycle. However, some locations will be characterized by uniformly
distributed precipitations or a precipitations maximum during the winter. For example, near the Equator the
precipitations will be plentiful and evenly distributed throughout the year (uniform distribution). Around the
Mediterranean Sea, the precipitations will be very scarce in the summer, and will fall mainly during the
winter (winter maximum).
Global precipitations patterns are also controlled by the movements of air masses. These movements are
linked to the global atmospheric circulation pattern.
CLIMATES CLASSIFICATION
There are different ways of classifying climates. Patterns of temperature and precipitations provide the main
basis for certain climate classification systems. These types of classification systems are called empirical.
They are based on weather statistics, or other data, used to determine general climate categories (e.g.
Köppen-Geiger system explained in your textbook).
The Christopherson’s classification (in you textbook) is a genetic classification system. It uses causative
factors to determine climatic regions; for example, an analysis of the effect of interacting air masses. This is
the case because air mass characteristics control the two most important climate variables (temperature
and precipitations). Thus, we can explain certain climates using air masses as a guide. Seasonal
movements of frontal zones (boundaries between air masses) therefore influence annual cycles of
temperature and precipitations (especially for midlatitudes climates). Frontal zones move with the seasons
and the location of cyclones and anticyclones (e.g. Hawaiian High and Aleutian Low).
MICROCLIMATES
Regional characteristics will lead to the development of microclimates. A microclimate is the climate within a
small, defined area, which is different from its surrounding area. Microclimates are linked to changes in
topography (higher or lower elevation than surrounding area), or the proximity of bodies of water. For
example, Mount Lemmon experiences a different temperature and precipitations regime than Tucson.
Human settlements will also lead to the creation of microclimates that are referred to as urban heat islands.
The urban heat island microclimate is linked to the tendency for urban areas to have warmer air
temperature at night than the surrounding rural landscape, due to the low albedo of streets, sidewalks,
parking lots, and buildings. These surfaces absorb solar radiation during the day and release it at night,
resulting in higher night temperature.
LAB QUESTIONS
SECTION A: Climograph construction and interpretation
1. Using the precipitations and temperature data in tables 1 to 4, construct a climograph for each city on
figures 1 to 4. Using your atlas, determine the latitude and longitude for each location.
N.B. Represent each variable using the right type of graph: bars for precipitations and continuous line for temperature.
Bars cannot touch each other since precipitations are a discrete variable.
Table 1. Manaus, Brazil
Month
Average
Sunlight (hours)
Average Temperature
(°C)
Average
Precipitations (cm)
Jan
Feb
4
4
27.5
27.5
24.9
23.1
March
April
4
4
27.5
27.5
26.2
22.1
May
June
5
7
27.5
27.5
17.0
8.4
July
Aug
8
8
28
28.5
5.8
3.8
Sept
Oct
8
7
28.5
28.5
4.6
10.7
Nov
Dec
6
5
28.5
28
14.2
20.3
Table 2. Walvis Bay, Namibia
Month
Average
Sunlight (hours)
Average Temperature
(°C)
Average
Precipitations (cm)
Jan
Feb
7
7
19
19.5
0
0.5
March
April
7
8
19
18.5
0.8
0.3
May
June
8
8
17
16
0.3
0
July
Aug
8
7
14.5
14
0
0.3
Sept
Oct
6
7
14
15
0
0
Nov
Dec
7
7
17
18
0
0
Table 3. Athens, Greece
Month
Average
Sunlight (hours)
Average Temperature
(°C)
Average
Precipitations (cm)
Jan
Feb
4
5
9.5
10.5
6.2
3.7
March
April
6
8
12
15.5
3.7
2.3
May
June
9
11
20.5
25
2.3
1.4
July
Aug
12
12
28
28
0.6
0.7
Sept
Oct
9
7
24
19.5
1.5
5.1
Nov
Dec
5
4
15.5
11.5
5.6
7.1
Average
Sunlight (hours)
Average Temperature
(°C)
Average
Precipitations (cm)
Feb
2
3
2.5
4
21.8
14.7
March
April
4
6
6.5
9
12.7
8.4
May
June
8
7
13
16
7.1
6.4
July
Aug
9
8
17.5
17.5
3.1
4.3
Sept
Oct
6
4
13.5
10.5
9.1
14.7
Nov
Dec
3
2
6.5
4
21.1
22.4
Table 4. Vancouver, Canada
Month
Jan
25
25
20
20
15
15
10
10
5
5
0
-5
30
30
Temperature (C)
Temperature (C)
30
35
25
25
20
20
15
15
10
10
5
5
0
0
-5
Precipitation (cm)
30
Precipitation (cm)
35
0
J F M A M J J A S ON D
J F M A M J J A S ON D
Month
Month
Figure 1. Mean monthly temperature and
precipitations for Manaus, Brazil
Figure 3. Mean monthly temperature and
precipitations for Athens, Greece
30
25
25
20
20
15
15
10
10
5
5
0
-5
30
30
0
Temperature (C)
Temperature (C)
30
35
Precipitation (cm)
35
Latitude: ______________________________
Longitude: ____________________________
25
25
20
20
15
15
10
10
5
5
0
-5
Precipitation (cm)
Latitude: ______________________________
Longitude: ____________________________
0
J F M A M J J A S ON D
J F M A M J J A S ON D
Month
Month
Figure 2. Mean monthly temperature and
precipitations for Walvis Bay, Namibia
Figure 4. Mean monthly temperature and
precipitations for Vancouver, Canada
Latitude: ______________________________
Longitude: ____________________________
Latitude: ______________________________
Longitude: ____________________________
2. Use the climographs you plotted to answer the following questions.
a) Using the Christopherson’s climate classification (in your textbook), identify the climate type for each city.
Use the climographs and maps from your textbook as guides.
Manaus: ____________________________________________________________________________
Walvis Bay: __________________________________________________________________________
Athens: _____________________________________________________________________________
Vancouver: __________________________________________________________________________
b) For each city, identify and explain the controlling factors on temperature and precipitations.
Manaus:
Walvis Bay:
Athens:
Vancouver:
SECTION B: Factors controlling temperature variability
1. Tables 5 and 6 display the average sunlight, and average monthly temperature and precipitations for
Halifax, Canada and Bordeaux, France.
a) Determine the latitude and longitude of both locations:
Halifax: ________________________________________
Bordeaux: ______________________________________
b) Determine the climate of each location.
Halifax: ________________________________________
Bordeaux: ______________________________________
Table 5. Halifax, Canada
Month
Average
Sunlight
(hours)
Average
Temperature (°C)
Average
Precipitations
(mm)
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
3
4
5
5
6
7
8
7
6
5
3
3
-4.5
-5
-1
3.5
9.5
14.5
18
18
14.5
9.5
4
-2
137
109
125
114
104
102
97
112
104
137
135
137
Table 6. Bordeaux, France
Month
Average
Sunlight
(hours)
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
3
4
5
7
7
8
9
8
7
5
3
2
Average
Temperature (°C)
5.5
6.5
9.5
11.5
14.5
18
19.5
20
17.5
13
9
6
Average
Precipitations
(mm)
90
75
63
48
61
65
56
70
84
83
96
109
c) Which factors are responsible for the temperature differences between Halifax and Bordeaux?
N.B. The answer will not necessarily found in the climates chapter. Think about all the factors that control temperature on
a local and global scale.
SECTION C: Matching locations with climographs
The map on figure 5 shows the locations of 8 cities in the United States.
N.B. The data on these climographs are in English units (°Fahrenheit and inches).
1. Match each climograph on figure 6 to the appropriate city on figure 5. Base your pairing on the
temperature and precipitations averages as well as their annual pattern of variability. Use the
Christopherson’s climographs and maps of distribution of climates in your textbook as guides.
For each city, give the corresponding station number and an explanation for your choice.
N.B. There is only one climate per city. You need to use all stations. There are no repetitions.
Eugene, OR: station #_____.
Explanation:
Fresno, CA: station #_____.
Explanation:
Phoenix, AZ: station #_____.
Explanation:
Hilo, HI: station #_____.
Explanation:
Lubbock, TX: station #_____.
Explanation:
St. Paul, MN: station #_____.
Explanation:
Nashville, TN: station #_____.
Explanation:
Boston, MA: station #_____.
Explanation:
Figure 5. Map of eight cities
Figure 6. Climographs for eight cities
SECTION D: Microclimates
1. Identify the climate for each city.
San Francisco: ___________________________________________________________________
Fresno: __________________________________________________________________________
2. Why is the total annual rainfall higher in San Francisco than in Fresno?
3. Disregarding the differences in latitude, why would the average annual temperature be lower in San
Francisco than in Fresno?
4. Why is the annual range of temperature greater in Fresno than in San Francisco?
5. Why is the annual precipitations pattern for both cities showing a dominance of winter precipitations?
Explain.
EXTRA CREDIT (1 point)
To be completed outside the lab period
SECTION A: Deserts’ climates
1. Using the precipitations and temperature data in tables 1 and 2, construct climographs for Tucson and
Las Vegas on figures 1 and 2.
Table 1. Mean monthly values of air temperature and precipitations for Tucson, AZ
Temp. (°C)
Precip.(cm)
Jan.
10.7
2.31
Feb.
12.4
2.01
Mar.
14.8
1.80
Apr.
18.8
0.99
May
23.3
0.51
June
28.8
0.79
July
30.3
5.31
Aug.
29.2
5.31
Sept.
26.9
2.79
Oct.
21.3
1.50
Nov.
15.1
2.01
Dec.
11.1
2.31
Table 2. Mean monthly values of air temperature and precipitations for Las Vegas, NV
Apr.
17.8
0.53
May
23.3
0.71
June
29.4
0.30
July
32.8
0.89
Aug.
31.5
1.24
40
6
30
5
20
4
10
3
0
2
-10
Sept.
26.9
0.71
Precipitation (cm)
Mar.
13.5
1.07
1
-20
-30
0
J F M A M J J A S O N D
Month
Figure 1. Climograph for Tucson, AZ
40
6
30
5
20
4
10
3
0
2
-10
Precipitation (cm)
Feb.
10.6
1.22
Temperature (degrees C)
Jan.
7.5
1.22
Temperature (degrees C)
Temp. (°C)
Precip.(cm)
1
-20
-30
0
J F M A M J J A S O N D
Month
Figure 2. Climograph for Las Vegas, NV
Oct.
20.2
0.53
Nov.
12.8
1.09
Dec.
7.6
0.97
2. Identify the climates of Tucson and Las Vegas using the Christopherson’s classification.
Tucson: ____________________________________________________________________________
Las Vegas: __________________________________________________________________________
3. Compare the climates of Tucson and Las Vegas. Focus on the differences and similarities between both
climates.
4. What are the main factors that make Tucson and its surroundings a desert?
5. What are the main factors that make Las Vegas and its surroundings a desert?
6. Explain the annual pattern of precipitations in Tucson in details, concentrating on the controlling factors.