Climate Classification

The climate hypothesis of Civilisation

This hypothesis advocated by Ellsworth Huntington states that:

“There is a causal relation between stimulating climate and

human inventiveness” this hypothesis assumes that

“we are what suns and winds and water makes us”

Climate & Weather

Weather refers to the state of atmosphere at any given time denoting

the short term variations of atmosphere in terms of temperature, pressure,

wind, moisture, cloudiness, precipitation and visibility. Weather is highly

variable changing from hour to hour and at other times day to day.

Climate, on the other hand, is the sum total of the variety of weather

conditions of an area or a place. Thus climate may be defined a simply as

'average weather'. The term climate denotes a description of aggregate

weather conditions.

Horizontal Distance (km) Vertical Scale (km) Time Scale

Global > 10,000 20 – 100 km > 1 week

Regional/Macroclimate100 x 10,000 1 – 20 km12 hrs – 1week

Local/Mesoclimate 1 to 100 10 m to 1 km 1 - 12 hoursMicroclimate Upto 1 km Upto 10 m < 1 hours

Climatic Zones of the World

In order to classify Climatic Zones, climate can be considered at a

variety of spatial and time scales.

Approx. Characteristic Dimensions

Source: http://www.maf.govt.nz/sff/about-projects/search/L05-006/microclimate-06.pdf

Climate zone CharacteristicsPolar very cold and dry all yearTemperate cold winters and mild summersArid dry, hot all yearTropical hot and wet all yearMediterranean mild winters, dry hot summersMountains (Tundra) very cold all year

At the geographic world map level, the Zonal classification is based on maximum and minimum temperatures and the temperature range as well as the total and seasonal distribution of precipitation. A simple summary of climatic zones is as follows:

Summary of climate zones

Within the same climatic zone, some locations may have contrasting or variable climatic conditions. These may be caused by the following factors: Latitude Temperature range increases with distance from the equator. Also, temperatures decrease as you move away from the equator. This is because the suns rays are dispersed over a larger area of land as you move away from the equator. This is due to the curved surface of the earth. In addition Polar Regions are colder because the suns rays have further to travel compared to place on the equator. Altitude Temperatures decrease with height. The air is less dense and cannot hold heat as easily.

WindsIf winds are warm - they have been blown from a hot area - they will raise temperatures. If winds have been blown from cold areas they will lower temperatures.

Distance from the seaLand heats and cools faster than the sea. Therefore coastal areas have a lower temperature range than those areas inland. On the coast winters are mild and summers are cool. In inland areas temperatures are high in the summer and cold in the winter.

AspectSlopes facing the sun are warmer than those that are not. Thus south facing slopes in the northern hemisphere are usually warm whereas slopes facing north in the southern hemisphere are warmest.

Many different systems of climate classification are in use for different purposes. Climatic zones such as tropical, arid, temperature and cool are commonly found for representing climatic conditions. For the purposes of building design a simple system based on the nature of the thermal problem in the particular location is often used.

Cold climates, where the main problem is the lack of heat (under heating), or an excessive heat dissipation for all or most parts of the year.

Temperate climates, where there is a seasonal variation between underheating and overheating, but neither is very severe.

Hot-dry (arid) climates, where the main problem is overheating, but the air is dry, so the evaporative cooling mechanism of the body is not restricted. There is usually a large diurnal (day - night) temperature variation.

Warm-humid climates, where the overheating is not as great as in hot-dry areas, but it is aggravated by very high humidities, restricting the evaporation potential. The diurnal temperature variation is small.

The general climate (macroclimate) is influenced by the topographty, the vegetation and the nature of the environment on a regional scale (mesoclimate) or at a local level within the site itself (microclimate).

Climatic Zones in India

India possesses a large variety of climates ranging from extremely hot desert regions to high

altitude locations with severely cold conditions similar to northern Europe.

Within India it is possible to define six regions with distinct climates. The six climates are

normally designated as:

Hot and Dry,

Warm and Humid, Moderate, Cold and Sunny, Cold & Cloudy and Composite.

The criteria of allocating any location in India to one of the first five climate zones are that

the defined conditions prevail for more than six months. In cases where none of these

categories can be identified for six months or longer, the climatic zone is called Composite.

On this basis, Bansal and Minke, 1988, originally produced the Climatic Zones in India

Map by evaluation of the mean monthly data from 233 weather stations, and then

delineating the six climatic zones.

Criteria of Bansal et al. Criteria of SP 7:2005 [9]

ClimateMean

Monthly Temp. (ºC)

Relative Humidity (%) Climate

Mean Monthly

Temp.(ºC)

Relative Humidity (%)

Hot & Dry >30 <55 Hot & Dry >30 <55Warm & Humid >30 >55 Warm &

Humid>30>25

>55>75

Moderate 25-30 <75 Temperate 25-30 <75Cold & Cloudy <25 >55 Cold <25 All values

Cold & Sunny <25 <55

Composite

This applies, when six months or more donot fall within any of the above catergories

Composite

This applies, when six months or more donot fall within any of the above catergories

Classification of Climates in India

Hot and Dry

Jaisalmer

Mean Monthly Temp. (°C) : > 30

Mean Monthly R.H. (%) : <55

Mean Monthly Preciptation : < 5

No. of Clear Days in a month : > 20

Places : Rajasthan, Gujarat

Very high daytime temperatures, with very little

precipitation and a short and mild winter season

characterize this climate. Another important

characteristic is a high diurnal temperature

variation. You can be boiling during the day and cold

at night. This is due to the rapid radiative heat loss

from the ground or the building to the clear night

sky.

The desert town of Jaisalmer deals with this by building homes that abut against each other, with the inner rooms opening towards small courtyards and the front rooms opening through screened openings towards narrow shaded streets. This pattern minimizes the exposure of building surfaces to the outside.

The buildings are of heavy mass and

the windows small, because of which

the indoor temperature changes very

little through the day or night, staying

close to a more comfortable daily

mean temperature.

In summers, even though the day is

hot, nights are cool, and people spend

time out on the roof terrace. Because

humidity is low, if water was

available, cooling by evaporation of

water would be an easy and effective

way of obtaining thermal comfort.

Warm and Humid

Trivandrum

Mean Monthly Temp. (°C) : >30

Mean Monthly R.H. (%)

Mean Monthly Precipitation : >5

No. of clear days in a month

Places : Trivandrum, Coastal Areas/ North East.

High humidity, strong sun, glare from the sky and horizon

characterize this climate. There are long monsoon periods with

heavy rain. But the breezes, especially in coastal areas, can alleviate

discomfort considerably.

The Padmanabhapuram Palace in Trivandrum, responds to the climate with steep sloping high tiled roofs, with deep eaves. The sides are open to the breeze, and air ventilates up through the porous tile roofs, ensuring that the indoor temperature does not build up.

Using open slatted or perforated

timber screens on sides of verandahs

cuts out glare, ensures privacy but

allows the breeze flow across the

rooms. Walls are white to reflect the

sun, and often completely shaded by

the verandahs.

For a cluster of buildings, an openness

of planning, to allow the natural

breeze to flow through them is of

paramount importance.

Cold & Sunny

Ladakh Mean Monthly Temp. (°C) : <25

Mean Monthly R.H. (%) : <55

Mean Monthly Precipitation : <5

No. of clear days in a month: >20

Places : Ladakh

Leh in Ladakh is a "mountain desert." There is very little precipitation and

the temperatures vary greatly between the day and night and also from

summer to winter

The traditional Ladhaki settlement is usually built on steep slopes facing southward. This allows good insolation during the day.

Heavy walls (mud) and a well

insulated roof (timber & mud)

dampen the variations of

indoor temperatures.

The use of glass and nowadays,

trombe- wall is very successful

as heat can be stored in the

building mass during the day,

to stay warm indoors at night.

Cold and Cloudy

Sauni Village, U.P.

Mean Monthly Temp. (°C) : <25

Mean Monthly R.H. (%) : >55

Mean Monthly Precipitation : >5

No. of clear days in a month : <20

Places : J&K, Himachal, NW UP, Niligiri

Winters are prolonged and summers are short in this climate. There is

also a fair amount of precipitation- snow or rain, often spread across the

year.

The traditional homes and villages of the sub - Himalayan region are built on hill slopes that would receive a fair amount of sunshine. The lower floor is occupied by cattle and used for storage. The upper floor which is away from cold and damp ground has the living rooms. The cooking area is a part of it, in order to benefit from the heat generated by it. Low timber ceiling provide insulation and conserve the warmth. Windows face the sun.

Moderate

BangaloreMean Monthly Temp. (°C) : 25-30

Mean Monthly R.H. (%) : <75

Mean Monthly Precipitation : <5

No. of clear days in a month : <20

Places : Bangalore, Deccan

This is a climate which is generally comfortable; neither too hot, nor too

cold, and where all of us should be staying! All you need to do is be

shaded and insulated from direct sun, let in a little breeze when you feel

stuffy or warm: and shut the window if it is chilly or wear some light

woolens.

In Banglore, the ideal comfortable house is built of heavy walls with high ceiling rooms, with windows that you can shut and open, surrounded by a shade giving verandah.

High ceilings reduce the

effect of heat that would

radiate down from the roof

which would get hot under

the sun. This will also allow

the warm air to rise and

escape through ventilators,

high up in the walls.