BW, BS,
Af, Am, Aw
Af
Am
Aw
60°
30°
0°
30°
60°
What do these all have in common?
Small group question: What leaf shape/shedding habit do
you expect to find in each of these and why?
Tropical Monsoon (Am)
Found primarily along eastern coastlines
Result of seasonal reversal of winds
Onshore, bringing rain in summer
Offshore, bringing drier conditions in winter
Desertification
: loss of
productive
potential due
to human
activity
No severe drought
Long growing season (it’s tropical)
Forest not as tall or diverse as Af
Broadleaf deciduous trees lose leaves in dry season
Aw = Tropical savanna
Period of severe drought
long dry season during
“winter” low sun season
High temps. = high PET
Can happen in
A climates as
well as in arid
climates
Aw: dry period is so long that broadleaf deciduous trees
cannot earn enough during wet season to pay for
leaves. Needleleaf trees or small leaves are best.
Trees are dormant in dry season.
Grasses and shrubs dominate
Located between Af and B
1
Baobab or Upside-Down Tree grows in Africa and Australia.
The legend says that after it was planted by God it kept
moving, so God replanted it upside down
Aw
Biomes:
Plant formations associated with major climate types.
Where is Aw located ?
What causes it to be
predictably wet and dry?
Pressure belts follow direct
vertical rays of sun.
In July, when sun is north of
Equator, ITCZ affects Aw 
rain in summer.
In January, when sun is
south of Equator,
Subtropical High affects Aw
 dry in winter.
EF
ET
Df
Cs
B
Aw
Af
Aw
B
Cs
Df
Where is Aw located ?
What causes it to be
predictably wet and dry?
Pressure belts follow direct
vertical rays of sun.
In July, when sun is north of
Equator, STH affects Aw 
dry in S. Hemis. winter.
In January, when sun is
south of Equator, ITCZ
affects Aw  rain in S.
Hemis. summer.
EF
ET
Df
Cs
B
Aw
Af
Aw
B
Cs
Df
EF
Tropical savanna
Desert
Temperate grassland
Temperate forest
Mediterranean scrub
Boreal forest
Tundra
Ice
ET
Tropical rainforest
EF
ET
Df
Cs
B
Aw
Af
Aw
B
Cs
Df
ET
ET
EF
EF
2
Biome: Biological community associated with
major climate region.
Changes in vegetation along precipitation gradient in “A”
E
A
D
Af
Am
Aw
B
C
Decreasing precipitation 
B
A
Decreasing precipitation 
Mangrove: tropical, low energy coastal, woody plants,
tolerate saltwater
Mangrove
Global mangrove distribution
Environmental issues associated with A climates
Mangrove destruction for aquaculture/wood chips
Rainforest clearing for agriculture / ranching
Honduras
Shrimp ponds, Indonesia
3
Climate Parameters: “A” and “E”
ET: “Tundra”
Northern Alaska, Canada,
Russia, Arctic Ocean shores
EF: “Frost”
Greenland and Antarctica,
ice caps
Tropical: never
below 64° average
Notice difference in temperature scales
Never freezes
Too cold
Polar:
for trees
never
above
50° average
Tundra in orange
Frost in white
Polar Climates: too cold for trees!
ET:
Tundra Climate
at least one month above freezing (but below 50ºF)
permafrost – frozen ground
around Arctic Ocean – coastal location moderates
temperature
low vegetation – shrubs and grasses
fauna migrate in for summer
some can freeze
What happens when water changes state from liquid to solid?
EF:
Frost Climate
never thaws out
water always locked up as ice
Antarctica and Greenland ice caps
World’s coldest temperatures
−89.2 °C (−128.6 °F) - Antarctica
too cold for any vegetation
penguins, polar bears, etc.
Tundra: Hrafntinnusker, Iceland
4
Biome: Biological community associated with
major climate region.
Frost climate: Antarctica
E
D
C
B
A
Decreasing precipitation 
C and D:
the inbetween
climates.
EF
E
A
C
How are
C and D
alike?
D
ET
E
Decreasing precipitation 
Characteristics of both C and D climates
E, C & D
Great variability
60°
Week to week…frontal passage
Seasonal…air mass dominance
30°
Zone of air mass contrasts
Lack constant heat of tropics or constant cold of polar
climates
0°
30°
60°
5
Worldwide Distribution of Climates “C” and “D”
“C” Mesothermal (Mild mid-latitude) climates:
summer dominated but can freeze
Cfa: Subtropical = Mobile, almost (but not) tropical
moist all year (small “f”)
warmest of C climates = “a”
dominated by mT air mass 
warm with high humidity, long summer
tropical storms in summer
SE U.S., SE China
dominated by temperate deciduous forest
southern pines
southern deepwater swamps
drier part is tall-grass prairie
In Cfa, enough water for vines
In Cfa, enough light gets
to forest floor for growth
Pines common on sandy soils of coastal plain
6
Cfa wetlands: Distribution of cypress in SE U.S.
Typical cypress trees in southern deepwater swamps
High stress, needleleaf deciduous, knees
Baldcypress versus
Spruce pine
In coastal saltwater “C” environments, trees cannot
survive dual strees of salt and freezes. Marsh “grasses”
and “reeds” dominate
Needleleaf deciduous
versus needleleaf
evergreen
Marine West Coast: Temperate rain forest
Cfb: Marine West Coast
“f” = moist all year
“b” = cooler than Cfa (shorter growing season)
dominated by mP air masses and
relatively warm ocean currents
rainy, drizzly, highest annual % cloud cover
Pacific northwest, western Europe
temperate marine conifer forest (temp. rain forest)
large needleleaf evergreens
large sized spruce & fir, redwoods (N. Amer.)
7
Cfa “subtropical”, mT
airmass, eastern side of
continent
Cfb “Marine West Coast”,
mP airmass, western side
of continent
Big needleleaf evergreens
Broadleaf deciduous
Pacific Coast Redwoods
Csa: Mediterranean
“s” = summer dry
drought during growing season
fire common
scrub, stunted woodlands, grass, bulbs
most near water bodies that moderate temperatures
around Mediterranean, southern California
influenced by subtropical high and polar front
Where is Cs located ?
What causes it to be
predictably wet and dry?
Pressure belts follow direct
vertical rays of sun.
In July, when sun is north of
Equator, Subtropical High
affects Cs  dry in summer.
In January, when sun is
south of Equator, Polar
Front affects Cs  wet in
winter.
EF
ET
Df
Cs
B
Aw
Af
Aw
B
Cs
Df
ET
EF
Where is Cs located ?
What causes it to be
predictably wet and dry?
Pressure belts follow direct
vertical rays of sun.
In July (winter in S. Hemis.),
when sun is north of
Equator, Polar Front affects
Cs  wet in winter.
In January (summer in S.
Hemis), when sun is south
of Equator, Subtropical High
affects Cs  dry in summer.
EF
ET
Df
Cs
B
“Mediterranean”
Cs
s= summer dry
Aw
Af
Aw
B
Cs
Df
ET
EF
8
Chaparral, Mediterranean scrub-shrub
(leathery leaves, coppice sprouting common)
Fires in San Bernadino, California after dry summer,
landslides occur during winter rains
Grasslands and large herbivores
North American
Grasslands
Drier parts of “C”
and “D” climates,
transitional to “B”
climates.
Ecotone
Biome: Biological community associated with
major climate region.
E
Cfb
D
C
Cfb
C
Cfa
B
A
drier
B
Decreasing precipitation 
Decreasing precipitation 
9