Transcript Document

Regional climates
Variety of different scales of climatic
investigations
•macroclimate- largest area of study, area
extends for 4 x 108 m2, up to 6000 m vertically
•(continental in scale)
•mesoclimate- 103 m2 up to 4 x 108 m2 in area
•(sub continental in scale)
•Local climate - a group of microclimates that
characterize a specific region; 103 to 108 m2 in
size
•Microclimate - the smallest category 1 to 104
m2 in area
•An individual field or park
Schematic of climatic scales of study
Climate classification: What, Why and How?
What:Organize regions with similar climates
Why:Understand what causes the climate to
be what it is and when to worry about
departures
How:Look at moisture, temperature,
evaporation, transpiration, vegetation,
altitude, latitude, etc. and decide on some
value that sets the boundary (threshold)commonly related to plants
Köppen climate classification scheme
Uses Monthly mean temps, monthly mean
precipitation, and annual mean temps to
establish major climatic zones
•designated with capital letters
Widely used but frequently criticized
•no agreement between plants and climate
•variability in the factors that set boundary
= climate classification changes constantly
Köppen Climate table
Class
Class name
A
Tropical humid
B
C
Subcategory Subcategory name
Af
Am
Aw
Dry
BWh
BSh
BWk
BSk
Mild Mid-Latitude Csa
Csb
Cfa
Cwa
Cfb
Cfc
Key characteristic for
sub categorization
No dry season
Short dry season; heavy
monsoonal rains in other
Tropical monsoonal months
Winter dry season
Tropical savanna
Subtropical desert Low-latitude desert
Subtropical steppe Low-latitude dry
Mid-latitude desert Mid-latitude desert
Mid-latitude steppe Mid-latitude dry
Mild with dry, hot summer
Mediterranean
Mild with dry, warm
summer
Mediterranean
Mild with no dry season,
hot summer
Humid subtropical
Mild with dry winter, hot
summer
Humid subtropical
Mild with no dry season,
Marine west coast warm summer
Mild with no dry season,
Marine west coast cool summer
Tropical wet
D
Severe
Mid-Latitude
Dfa
Dfb
Dwa
Dwb
Dfc
E
Polar
H
Highland
Humid
continental
Humid
continental
Humid
continental
Humid
continental
Subarctic
Dfd
Subarctic
Dwc
Subarctic
Dwd
Subarctic
ET
EF
Tundra
Ice Cap
Humid with severe
winter, no dry
season, hot summer
Humid with severe
winter, no dry
season, warm
summer
Humid with severe,
dry winter, hot
summer
Humid with severe,
dry winter, warm
summer
Severe winter, no
dry season, cool
summer
Severe, very cold
winter, no dry
season, cool summer
Severe, dry winter,
cool summer
Severe, very cold
and dry winter, cool
summer
Polar tundra, no true
summer
Perennial ice
Climate zones of the world
Divided into alphabetic categories
A, B, C, D, E, H zones
KÖPPEN Climate classification
Tropical climates designated with a capital “A”
Based in part on vegetation zones that are
sensitive to moisture and temperature
Tropical (A) Climates All tropical climates are warm
the subdivisions are based on differences in rain
Tropical Rainforest (Af) Climates located
0-15° N/S Lat.
Diurnal temperature range is greater than the
difference between the warmest and coolest
months
(annual range).
Every month has precipitation and no month is
deficient in rainfall. This high amount of
rainfall keeps the soil moisture at capacity. EVT
occurs at potential rate
Am- Tropical monsoonal climate
Diurnal temperature range is greater than the
difference between the warmest and coolest
months (annual range).
seasonal precipitation surplus and deficit
Distinctive dry and wet season related to wind
reversal
Aw- Tropical savanna climate
Diurnal temperature range is greater than the
difference between the warmest and coolest
months (annual range).
precipitation deficit much of the year
Distinctive dry and wet season
B climates - semi-arid to arid
Several sub categories
All B-climates have less than 30” of annual
precipitation
BW climates are arid (less than 10”) and
can be divided further based on latitude
(temperature)
BWh- low latitude hot and dry
BWk- mid latitude cool and dry
BWh is a function of Hadley cell circulation;
occur between 18 and 32° N-S Latitude
BS climates are semi-arid (more than 10”
but less than 30” of rain) and can be
divided further based on latitude (temps)
BSh- low latitude hot and dry
BSk- mid latitude cool and dry
A gradational change from A climates on
either side of the B climates
C climates- Mesothermal temperate
Warm summers (<10°C); Mild Winters (between -3
to 18°C)
Annual moisture distribution determines
subcategories
C-subcategories
Cf = moisture evenly distributed throughout the
year
Cw = 10x the amount of moisture in the summer
as compared to the driest winter month
Cs = 3x as much moisture in the winter as
compared to the driest summer month; at least 1
month with less than 3 cm of precipitation
Csa= called Mediterranean climate
•western edge of mid-latitude continents
Cfa= called a Humid subtropical climate
•Southeastern edge of mid latitude continents
Cfb= called Marine west coast
•Western edge of continents at higher latitudes
D climates- Severe Mid-latitude
All have severe winters; short summers that
range form hot in the south to cool to the
north
E climates - Polar No true summer
Cold all year long
Köppen climate regions of
North America
Köppen climate regions of the US
Trewartha climate classification scheme - a modified
version of the Köppen system.
Attempts to redefine the broad climatic groups in such a way
as to be closer to vegetational zoning.
Group A - this is the tropical climate group, defined as
places which do not receive annual winter frosts (in maritime
regions this corresponds closely to the Köppen boundary).
Climates with no more than 2 dry months are classified Ar ,
while others are classified Aw . There is no specific monsoon
climate identifier.
Group B - this is identical to the Köppen scheme.
Group C - in the Trewartha scheme this category includes
subtropical climates only (8 or more months above 10 °C).
The identifiers are the same as the first two letters of the
Köppen identifier - the Mediterranean climate is denoted Cs
and the humid subtropical climate, Cf or Cw .
Trewartha Climate scheme (Continued)
Group D - this group represents temperate climates.
Continental climates are represented as Dca (Köppen Dfa, Dwa,
Dsa ) and Dcb (Köppen Dfb ,Dwb ,Dsb ). Maritime temperate
climates (Köppen Cfb ,Cwb ,Csb ,Cfc ) are denoted Do in the
Trewartha classification. The dividing point between maritime
and continental climates is 0 °C in the coldest month, rather
than the usual Köppen value of -3 °C.
Group E - this group is undivided and contains the continental
subarctic climates (Köppen Dfc ,Dwc ,Dfd )
Group F - this is the polar climate group, split into Ft (Köppen
ET ) and Fi (Köppen EF ).
Group H - Highland climates - in which altitude is the most
important factor determining climate.
Other climate classification schemes
Thornthwaite-based his scheme on
moisture effectiveness and temperature
efficiency
•mathematical relationships easy to
identify from available meteorological
data
•Also uses info on season when rain or
snow falls
Genetic classification
Identifies the “Why” of climates first
and uses that information to establish
each climatic zone
-which air mass dominates
Air masses and climatic types
Warm
Wet
Tropical
wet
Tropical wet Tropical
and dry
dry
(desert)
Grp
I
mid
latitude
wet
Mid latitude mid
summer or
latitude
winter dry
dry
(desert)
Polar wet
Polar dry
and dry
(desert)
Grp
II
Polar wet
Cold
Dry
Grp
III
Climate zones determined by air mass
Vegetation
Closely linked to climate
Often used as PROXY data for lack of
climate data
5 distinct veggie zones
•Forests = trees; many different types of
forests
•e.g., hardwood, conifer, rainforest
•Deserts = discontinuous veggies; scrub brush;
cactus, etc.
•Grasslands = grasses
•Taiga = cold; climate evergreen conifer forests
•Tundra = cold; grasses sedges mosses and
lichens