1. (sub continental in scale)
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

2. Schematic of climatic scales of study

3. 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

4. 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

5. Köppen Climate table Key characteristic for Class Class name
Subcategory
Subcategory name
sub categorization A
Tropical humid Af
Tropical wet
No dry season
Short dry season; heavy
monsoonal rains in other Am
Tropical monsoonal
months Aw
Tropical savanna
Winter dry season B
Dry
BWh
Subtropical desert
Low-latitude desert
BSh
Subtropical steppe
Low-latitude dry
BWk
Mid-latitude desert
Mid-latitude desert
BSk
Mid-latitude steppe
Mid-latitude dry C
Mild Mid-Latitude
Csa
Mediterranean
Mild with dry, hot summer
Mild with dry, warm
summer
Csb
Mediterranean
Mild with no dry season,
Cfa
Humid subtropical
hot summer
Mild with dry winter, hot
Cwa
Humid subtropical
summer
Mild with no dry season,
Cfb
Marine west coast
warm summer
Mild with no dry season,
Cfc
Marine west coast
cool summer

6. Humid with severe
Severe
Mid-Latitude
Humid
continental
winter, no dry D
Dfa
season, hot summer
Humid with severe
winter, no dry
Humid
continental
season, warm
Dfb
summer
Humid with severe,
Humid
continental
dry winter, hot
Dwa
summer
Humid with severe,
Humid
continental
dry winter, warm
Dwb
summer
Severe winter, no
dry season, cool
Dfc
Subarctic
summer
Severe, very cold
winter, no dry
Dfd
Subarctic
season, cool summer
Severe, dry winter,
Dwc
Subarctic
cool summer
Severe, very cold
and dry winter, cool
Dwd
Subarctic
summer
Polar tundra, no true E
Polar ET
Tundra
summer EF
Ice Cap
Perennial ice H
Highland

7. Climate zones of the world
Divided into alphabetic categories
A, B, C, D, E, H zones

8. KÖPPEN Climate classification
Tropical climates designated with a capital “A”
Based in part on vegetation zones that are sensitive to moisture and temperature

9. 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

10. 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
precipitation deficit much of the year
Distinctive dry and wet season

11. B climates - semi-arid to arid
Several sub categories

12. 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

13. 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

14. C climates- Mesothermal temperate
Warm summers (<10°C); Mild Winters (between -3 to 18°C)
Annual moisture distribution determines subcategories

15. 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

16. 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

17. D climates- Severe Mid-latitude
All have severe winters; short summers that range form hot in the south to cool to the north

18. E climates - Polar No true summer
Cold all year long

19. Köppen climate regions of North America

20. Köppen climate regions of the US

21. 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 .

22. 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.

23. 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

24. Genetic classification
Identifies the “Why” of climates first and uses that information to establish each climatic zone
-which air mass dominates

25. Air masses and climatic types
Wet
Dry
Warm
Tropical wet
Tropical wet and dry
Tropical dry (desert)
Grp I
mid latitude wet
Mid latitude summer or winter dry
mid latitude dry (desert)
Grp II
Polar wet
Polar wet and dry
Polar dry (desert)
III
Cold

27. Climate zones determined by air mass

28. Closely linked to climate
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