Köppen divided the earth into five main climate zones, represented by a first capital letter (A-B-C-D-E) and long series of subzones (one or more letters) to specify a second character of the climate \cite{wikipediaa} as you can see in the picture above. These are their meaning:
- A (tropical-rainy) - With a constant high air temperatures (at sea level and low elevations) and monthly average air temperature always ≥ 18°C and consistent precipitation
- Af - in the Tropical rainforest climate ... rains! at least 60 mm/month and the air temperature doesn't change very much: nor during the day, nor during the year (aseasonal): at leas not as in other zones.
- Am - the Tropical monsoon climate has dry months with 60 mm, but more than negligible (1⁄25 the total annual precipitation
- Aw - the Tropical wet and dry or "savanna" climate, have long dry periods (>3 months) followed by rain periods
- B (dry) - Dry or arid climates are characterized by a very low precipitation. A threshold value is calculated as a function of average annual temperature (the higher the temperature, the higher the threshold) and precipitation during the warmest six months of the year (April through September in the Northern Hemisphere, or October through March in the Southern):
- BW - in Desert Climate, the annual precipitation is less than 50% of the threshold, (arid: desert climate).
- BS - in Semi-Arid or steppe Climates the annual precipitation is between 50% and 100% of this threshold.
and we add a third letter to identify climate as function of the average air temperature during the coldest month:
h if it is ≥0 °C;
k if below 0 °C. So we have
hot-dry (desert) (
BWh is Saharan desert, for example) and
cold-dry (desert) climate (
BWk is
Xinjiang and the north of
Kashmir),
Hot semi-arid (
BSh like Canary islands, central Africa, Spain ...) and C
old Steppe (
BSk is Afghanistan, Mongolia, ... and many others).
There is another climate sub-cathegory to be added, that is characterized by frequent fog and low clouds, although the actual precipitation received is very low, labelled BWn (Atacama desert, see \cite{Cereceda_2008}) and BSn (see the foggy coastal steppe in the Western Cape of South Africa).
- C (warm-temperate) - Temperate Climate or sub-tropical zones are characterized by the coldest monthly temperature between 0 and 18°C, by their precipitation pattern (second letter) and eventually by summer heat (third letter).
For what concerns rain: we distinguish dry winters (i.e. when the driest winter month sees less rain than one-tenth of the wettest summer month, in terms of average precipitation, and we add w); dry summers (i.e. when the wettest month of winter receives more than three times rain than the driest month of summer, and then we add s) and when the two extreme conditions are not fulfilled, we just add an f.
As a threshold for what concerns summer heat, we use the average temperature of the warmest month: if it is above (a) or below (b) 22 °C.
Few examples follow:
- Cwa - we can find Subtropical-Dry Winter climates in many places where dry winter/wet summer pattern is associated with tropical monsoonal climates like in Central Africa (Congo, Zambia), central South America (Córdoba, Argentina; Guadalajara, Mexico) or Indian peninsula (Islamabad, Pakistan; New Delhi, India; Kathmandu, Nepal) and more ... (Chengdu, Sichuan, China; Hong Kong; Hanoi, Vietnam).
- Cfa - close to the equator, on the eastern coasts and eastern sides of continents, we have the Humid subtropical climates with warm and moist conditions in the summer months and thundershowers (typical of southern United States, China and Japan)
- Cwb - The so-said Highland climates is mainly found in high altitude tropics of Central-South America (Cusco, Peru; La Paz, Bolivia; Salta, Argentina), in East and South Africa (Nairobi, Kenya; Addis Ababa, Ethiopia; Harare, Zimbabwe; Antananarivo, Madagascar; Johannesburg, South Africa) and other similar (Da Lat, Vietnam; Shimla, India; Kunming, China). Winters are dry and summers very rainy.
- Cfb - Oceanic Highland climates have uniform rainfall throughout the year (while Cwb have arid periods) sparse in continents like Australia and South America, among others, with a high diurnal temperature variation and low humidity, owing to their inland location and relatively high elevation (Quito, Pichincha Province, Ecuador; São Joaquim, Santa Catarina, Brazil; Boone, North Carolina, US; Orange, New South Wales, Australia; Cameron Highlands, Malaysia; Mount Hagen, Papua New Guinea.
- Csa - this is the most well known Mediterranean Climate: Beirut, Lebanon; Tangier, Morocco; Rome, Italy; Lisbon, Portugal; Izmir, Turkey (Csa); Rasht, Gilan Province, Iran; Los Angeles, California, Perth, Australia. In these places, between 30-45° (latitude) north or south, weather is influenced by polar climate, during winters, producing moderate temperatures and changeable, rainy weather, and by the subtropical high pressure systems, during summers, that are hot and dry, except in coastal areas, where summers are milder.
- Csb - If you go norther, you will find dry, cooler summer months and the Oceanic climate (Cfb), like in Coruña, Spain; Porto, Portugal; Potenza, Italy; San Francisco, California; Victoria, British Columbia, Canada; Cape Town, South Africa;
- Csc - Cool-summer Mediterranean climate
- Cfc - Oceanic Subpolar climates ....
- D (cool-no-frost) - as in C but colder during the year, they have an average temperature above 10 °C their warmest months, and a coldest month average below 0 °C, they usually occur in the interiors of continents and north of 40°N, while in the Southern Hemisphere, group D climates are extremely rare. We use the same couple of letters to identify arid periods and summer characteristics:
- Dfa - Continental Climates with hot summer (average temperature in the warmest month >22 °C) occurs in Kazakhstan (Almaty, Oral), Japan (Aomori, Nagano, Sapporo, that is a little more cold and may be classified also Dfb), as well as in north America (Chicago, Boston, Minneapolis, Toronto, Montreal, but canadian are very close to Dfb) in Europe (Bucharest, Romania; Rostov-on-Don, Russia) and Asia (Pyongyang and Seoul, Korea; Beijing and Harbin, China).
- Dfb - if, from a Cfb with warm summer, we go norther (or souther, in austral emisphere), generally in the high 40s and low 50s latitudes, in North America or Asia, and in higher latitudes, in central and eastern Europe, you usually find a continental equivalent of a maritime temperate climate. Few examples: Kushiro, Hokkaido, Japan; Stockholm, Sweden; Oslo or Lillehammer, Norway; Helsinki, Finland, and Tallinn, Riga, Vilnius, Saint Petersburg on the baltic; Kiev, Ukraine; Budapest and Moscow; but also Calgary, Quebec City, Ottawa, in Canada; Buffalo, Portland and Marquette, in US; Heihe, China ...
- Dwa (cold - and dry - winters with hot summers is characteristic especially of China)
- Dwb (cold - and arid - winters with warm summers).
- Dsa (Dry summer) climates are found at higher elevations adjacent Mediterranean (Csa) climates like in Bishkek, Kyrgyzstan; Saqqez and Arak, Iran; Hakkâri and Muş, Turkey; Cambridge, Idaho, United States (Dsa).
- Dsb (continental climates) arises from the same scenario as Dsa, but at higher altitudes or latitudes, mostly in North America (Mediterranean climates extend further poleward than in Eurasia). Few examples: Sivas, Turkey; Roghun, Tajikistan; Dras, India; Flagstaff, Arizona (US).
- E (polar). Polar climates are characterized by average temperatures of any month below 10 °C and divided in, tundra climates and icecap climates:
- Tundra climates (ET and ETf): have average temperature of the summer months between 0 and 10 °C. These climates occur on the northern edges of the North American and Eurasian land masses (generally north of 70 °N), and on nearby islands.
- Ice cap climate (EF): This climate is dominant in Antarctica and inner Greenland, but also occurs at extremely high altitudes on mountains, above even tundra. Monthly average temperatures never exceed 0 °C.
- Ice cap climate (EF): This climate is dominant in Antarctica and inner Greenland, but also occurs at extremely high altitudes on mountains, above even tundra. Monthly average temperatures never exceed 0 °C.
The architecture point of view
Vernacular architecture
The term "vernacular" has a linguistic origin: the latin vernaculus means "native idiom". But we frequently use linguistic analogies also in architecture: grammar, style, expression, even syntax and language are terms that may be used to analyze a building, as well as linguists analyze the structure of a text.
As a local dialect, the vernacular architecture is the local «common speech of building» [Olivier 1997, p.xxi].
Architecture (the vernacular in particular) may be strongly influenced by climate, but the environment is not the only force that influence the form and the structure of a building. The site (e.g. the presence of water but also the presence of natural defences and physical boundaries), the most incumbent risks (those that can be reminded by people, like landslides and flood, earthquake and singular meteorological events), the economic development of a region and its effect on urbanization, the social and cultural uses (the property ownership system, the social structure, from the family and the food production, to the political organization, the dwelling stability, the rites, the traditions and the symbolic values); the available technologies (from the available materials to the available labour forces and their organization): all these factors have a strong influence on the architecture.
But «climates stimulate needs for shelter and influence local cultures, but provide the conditions of local building materials».
Climate data and variables
Air temperature
Relative Humidity
Solar power
Sky vault temperature
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Wind velocity
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Air pressure
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