Lecture 11: Climate
Weather
Climate
a) air temperature
b) atmospheric pressure
c) humidity
d) clouds
e) precipitation
f) visibility
g) wind
Long term averages
of weather (eg
(eg.. 30 y)
Means
Extremes
Variability
Geog 1000 Introduction to Physical Geography Fall 2012 : Dr. Hester Jiskoot, University of Lethbridge
WEATHER
Æ Conditions in the troposphere at present and over a short period of
time.
Æ Can be wet or dry, hot or cold, cloudy or clear, and windy, stormy or
calm.
MICROCLIMATE
Æ The climate of any small area/region: can be distinct from the surrounding
area.
Æ Influenced by soil moisture, vegetation, water bodies, topography, etc.
CLIMATE
Æ Long-term average weather conditions describing what generally
happens
Æ Usually classified according to average monthly temperature and
precipitation
Examples of microclimate:
Warmer day-time temperatures and colder night-time temperatures are found in
river valleys.
Cooler temperatures and stronger wind occur at higher elevations
(e.g. Cypress Hills & several mountain ridges in Waterton Park)
“CLIMATE IS WHAT YOU EXPECT,
WEATHER IS WHAT YOU GET.”
WEATHER ≠ CLIMATE
EARTH CLIMATE WITH INTERACTING INTERNAL AND EXTERNAL PROCESSES
1
ANNUAL AVERAGE PRECIPITATION
WORLD TEMPERATURE RANGES
Æ distribution determined by temperature, atmospheric pressure distribution, air
mass types, lifting mechanism, water-land distribution and distance from the equator.
CLIMATOLOGY
The study of climate
ATMOSPHERIC SCIENCE
The study of processes in atmospheric driving climate and weather
FACTORS DETERMINING CLIMATE
FOR A GIVEN LOCATION:
1. Latitude
In 1900 Wladimir Köppen
introduced the first mathematical
system of climatic classification,
based on empirical observations
2. Ratio of water to land
The system was updated by him (and colleague
Rudolf Geiger) until his death in 1940.
3. Wind systems
The final version was published by Geiger in
1961.
4. Topography
KÖPPEN-GEIGER CLIMATE CLASSIFICATION:
Æ Climate classes combine temperature and precipitation characteristics,
with limits and boundaries fitted into known vegetation and soil distributions
CLIMATE CLASSIFIED ACCORDING TO TEMPERATURE AND PRECIPITATION
Köppen system: basic letters
A
Tropical climates
Æ Coldest month T > 18°C
Æ Precipitation > Evapotranspiration
B
Dry: arid and semi-arid climates
C
Mesothermal climates (middle T)
Æ Precipitation < Evapotranspiration
Æ Seasons
Æ Warmest month T > 10°C
Æ Coolest month 0°C < T < 18°C
D
Microthermal climates (low T)
Æ Warmest month T > 10°C
Æ Coldest month T < 0°C
Æ Snow
E
Polar climates
H
Highland climates
Æ Warmest month T < 10°C
2
KÖPPEN-GEIGER CLIMATE MAP
A
B
C
KÖPPEN-GEIGER CLIMATE MAP
With ocean currents, air masses, dominant air pressure systems, and ITCZ position
D
E
H
Köppen system: additional letters
a = hot summer
b = warm summer
c = cool summer
d = cold winter
k = kalt (cold)
h = heiss (hot)
w = winter trocken (winter dry)
s = sommer trocken (summer dry)
m = monsoon
H = Hochbirge (Mountainous)
T = Tundra
S = Steppe
W = Wüste (desert Æ precip < 0.5*evap)
So………..Dfa = ???
Köppen Climate Chart (2)
D
Severe Mid-Latitude Dfa
Dfb
E
H
Polar
Köppen Climate Chart (1)
A
B
C
Tropical humid
Dry
Mild Mid-Latitude
Af
Tropical wet (rainforest)
Am
Tropical monsoonal
Aw
Tropical savanna (winter dry)
BWh
Subtropical desert
BSh
Subtropical steppe
BWk
Mid-latitude desert
BSk
Mid-latitude steppe
Csa
Mediterranean (dry hot summer)
Csb
Mediterranean (dry warm summer)
Cfa
Humid subtropical (no dry season)
Cwa
Humid subtropical (winter dry)
Cfb
Marine west coast (warm summer)
Cfc
Marine west coast (cool summer)
THE CONTINENT OF AFRICA KÖPPEN-GEIGER CLIMATE CLASSIFICATION
Humid continental (no dry season, hot summer)
Humid continental (no dry season, warm summer)
Dwa
Humid continental (dry winter, hot summer)
Dwb
Humid continental (dry winter, warm summer)
Dfc
Subarctic (cool summer)
Dfd
Subarctic (very cold winter, cool summer)
Dwc
Subarctic (dry winter, cool summer)
Dwd
Subarctic (very cold and dry winter, cool summer)
ET
Tundra (no true summer)
EF
Ice Cap (perennial ice)
EM
Marine
Highland
3
Lethbridge, AB
700
40
Temperature Range
Average Annual Temperature
Total Annual Precipitation
Total Summer Precipitation
Total Winter Precipitation
Köppen Classification
700
40
600
30
500
20
400
10
300
0
200
-10
0
-30
jan
oc
t
no
v
de
c
ja
Temperature Range
Average Annual Temperature
Total Annual Precipitation
Total Summer Precipitation
Total Winter Precipitation
Köppen Classification
45
-5
315
180
135
Dfc
Temperature Range
Average Annual Temperature
Total Annual Precipitation
Total Summer Precipitation
Total Winter Precipitation
Köppen Classification
oct
-20
-30
nov
100
0
dec
-20
sep
100
jul
-10
aug
200
jun
0
apr
300
27°N, 88° E
2134 m asl
may
10
feb
400
mar
20
Precipitation (mm)
500
Temperature (°C)
30
ju
l
au
g
se
p
600
n
fe
b
m
ar
ap
r
m
ay
ju
n
Precipitation (mm)
Darjeeling,
India
Temperature (°C)
40
Dawson City
64°N, 139° W
380 m asl
26
6
368
281
106
BSk
Darjeeling, India
Dawson, YK
700
Temperature (°C)
-30
oct
-20
0
nov
100
dec
-10
jul
200
sep
0
jun
10
300
aug
400
apr
20
jan
of a monthly average temperature and precipitation graph.
30
500
may
Characterisation of climate for a certain location in the form
600
feb
49°N, 112° W
929 m asl
mar
CLIMOGRAPHS
Precipitation (mm)
Lethbridge
12
12
3091
2847
244
Cwb
AGROCLIMATIC ATLAS FOR ALBERTA
Alberta has a continental climate with warm summers and cold
winters.
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/sag6294
Information about climate in relation to agriculture:
The agricultural area of the province (Prairie region) has a
semiarid climate because the annual precipitation is less than the
water evaporated by the wind and heat, and transpired by plants.
Agriculture interesting in specific climate elements
•
Precipitation
•
Temperature
•
Heat units
•
Frost free period
•
Growing season length
4
Crop or insect
Minimum threshold
temperature (°C)
Wheat
0.0
Barley
0.0
Spinach
2.2
Lettuce
4.4
General plant growth
5.0
Canola
5.0
Forages
5.0
Cabbage maggot
6.0
Potatoes
7.0
Variegated cutworm
7.0
Corn and beans
10.0
Grasshoppers, corn borers
10.0
General insect development
15.0
EXTREME MINIMUM TEMPERATURE
LENGTH OF GROWING SEASON
ANNUAL AND WINTER TOTAL PRECIPITATION
MEAN WIND SPEED IN WINTER AND SUMMER
Canadian climate normals 1971-2000
http://climate.weatheroffice.gc.ca/climate_normals/index_e.html
5
Reading for Friday
Chapter 7 p. 251-259
and
Appendix B (Köppen climate system: 591-593)
Note that we skip CHAPTER 6 for now
6