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Manual of tropical housing and building climatic design pdf

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Manual of tropical housing and building: climatic by O H Koenigshberger · Manual of tropical housing and building: climatic design. by O H Koenigshberger. Manual of tropical housing and building / O.H. Koenigsberger [et al.] Koenigsberger, O. H. (Otto H.), [and others]. Part 1., Climatic design. [Harlow]: Longman. Download as PDF, TXT or read online from Scribd Climatic Design . Paix: The design of buildings for daylighting Commonwealth Exp. The first draft of the Manual served to structure their discussions and was gradually developed and changed in Yet the most pressing housing needs of the tropics are urban.


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AFTER a sporadic start in the early nineteen-fifties, books in English on the design of buildings in relation to climate appeared at a rate which reached. MANUAL OF TROPICAL HOUSING AND BUILDING For our entire .. composite climates Shelter for tropical upland climates 8 Design aids. by O H Koenigsberger, T G Ingersoll, Alan Mayhew. Designed as a textbook for students of architecture, housing, environmental design and climate control in tropical countries, this book deals with the theory of climatic design and shows how practical solutions are derived from.

Smaller dust particles being in suspension in the air stream are carried more freely and may reach a height of 1 m or more. Here again. Fig 29 Bioclimatic chart for men at sedentary work — wearing 1 clo. Figure The amount of moisture the air can hold the saturationpoint humidity: Solar radiation alternates between conditions found in the warm-humid and the hot-dry desert climates. On a hilly site the greatest wind speeds will be experienced at the crests of hills.

Acknowledgements The following illustrations are based on those given in the publications listed. Authorship of the originals and their use as a basis is gratefully acknowledged.

Digest No 42 Estimating daylight in buildings Fig C. Environmental warmth and its measurement Medical Research Council. Most have been converted to S. Fig 21 R. Air movement and natural ventilation in Architects' Journal. Fig 99 J. List of figures A absorption g glare in general or glare constant A area of surface HSI heat stress index a absorbance absorption coefficient h height AH absolute humidity l intensity AMR annual mean range la intensity of direct radiation AMT annual mean temperature ld intensity of diffuse radiation At total surface area 1o reference intensity sound b thickness breadth IRC internally reflected component C conductance K thermal diffusivity k conductivity CET corrected effective temperature CS contrast sensitivity L luminance Cnd conduction Lh luminance at horizon Cnv convection Lz luminance at zenith c specific heat Ly luminance at y altitude angle D dirt factor M mass per unit surface DBT dry bulb temperature Met metabolism DF daylight factor MF maintenance factor d density MRT mean radiant temperature.

Qs solar heat gain. Szokolay prepared the manuscript for publication. It was designed to meet the demands of students from tropical countries for a syllabus centred on their specific needs.

Manualoftropicalhousing Koenigsberger 150824122547 Lva1 App6892

The first draft provided the nucleus for a course in tropical architecture started in with E. Some twenty to thirty architects. Alan Mayhew. After about ten years T. Preface and acknowledgements This book is intended as a textbook for students. I started working on the manual in to record the experience of twelve years of planning and building in India. He re-wrote some chapters and added others on the basis of his teaching experience in Africa and authoritative knowledge of building science.

My fellow authors join me in recording their gratitude to the many colleagues and students who helped during the long gestation period of this manual. University College. He also undertook and completed the. It is the result of the joint efforts of its authors. The first draft of the Manual served to structure their discussions and was gradually developed and changed in the 'give and take' between teachers and students. My particular thanks go to the trustees of the Halley Stewart Trust who had the foresight of financing the beginning of the work.

He receives money for his labour and is. In the Nile Valley. Given technological limitations and the always overriding considerations of safety. Children and adults spend most of the day in the open. This is demonstrated convincingly by going through the above-described features of rural life and noting how few of them apply in towns and cities.

Monetary transactions are minimal. Traditional rural building is based on low investment and high maintenance. Yet the most pressing housing needs of the tropics are urban. Egypt and the Maghreb countries. The traditional building forms of the rural tropics often include sound solutions of climatic problems. Everybody is a house builder as much as he is cultivator or herdsman. The assistance of relations. The functions of huts and houses are reduced to three: Introduction For most of the tropics.

The rhythm of city life does not include time for house building. Some of the countries of the arid belt of the northern hemisphere. The surrounding country provides the building materials: The rhythm of country life includes time for building as much as for tilling. Building materials that have to be brought in over large distances cease to be cheap.

Waste disposal and health problems are solved. Building materials for city needs cannot be taken from the surrounding countryside without. The safe storage of agricultural products receives as much — and often more — attention than shelter for human beings.

There are a few exceptions. The majority of the people of the tropics still live dispersed in low density rural settlements and deal with their housing problems in the same manner as their fathers and forefathers have done.

Traditional house types have developed in response to the needs of a predominantly peasant population. Growing family or tribal units can be accommodated easily by the addition of huts. Even time for maintenance work becomes scarce and the townsman soon learns to value durable materials and methods that do not need frequent attention.

Space is plentiful. Yet in most rural communities. Fire hazards. The resulting urban environment is climatically and socially inadequate. Yet it is space.

His family. Because he wants to be near to. Detroit or Montreal. It is the purpose of this manual to demonstrate that this need not be so. A wealthy elite can escape the consequences of poor design through mechanical airconditioning. Proximity makes major issues out of problems that the villager can afford to neglect.

It seems so obvious that house types and building materials from cold climates cannot solve the problems of cities where heat is the dominant problem and that solutions from communities with average per capita incomes of S7 per annum cannot work in communities where the income is less than S Safe storage of possessions is even more important than in the open country. So is privacy.

Yet the cities of the tropics are full of galvanised iron roofs. The others suffer from living conditions that permit neither efficient work nor rest or enjoyment. It is not a matter of the total amount of land available. They cannot be solved either by the adoption of Western technology and Western patterns that have their origin in different climates. Section 1 Climate: The given conditions 1. A somewhat more scientific definition is: Tropical climates are those where heat is the dominant problem.

Before tropical climates can be examined in detail.

According to human means of perception we can distinguish: Due to the tilted position. The earth moves around the sun in a slightly elliptical orbit. Figure 1 clearly explains this relationship. The spectral energy distribution varies with altitude. The axis of this rotation the line joining the North and South Poles is tilted to the plane of the elliptical orbit.

This orbit results from the gravitational pull of the sun and the centrifugal force due to the earth's inertia and momentum. As the luminous efficiency of energy-radiation depends on its spectral composition. This is the main cause of seasonal changes. Some of the shorter wavelengths are absorbed by the atmosphere and reradiated at much longer wavelengths. For all areas of the earth these are the equinox days day and night of equal length.

At aphelion the solar distance is million km and at perihelion is is million km. On 21 March and 23 September areas along the Equator are normal to the sun's rays and experience a zenith path of the sun. The earth receives almost all its energy from the sun in the form of radiation.

One revolution is completed in days. On 21 June areas along latitude At the same time latitude Maximum intensity is received on a plane normal to the direction of radiation.

If the axis of earth were rectangular to the plane of the orbit. Figure 3 indicates this geometrical relationship and Figure 4 shows this effect in quantitative terms for points at different heights above sea-level.

Figure 2 shows how the same amount of radiation is distributed over a larger area. This atmospheric depletion is also affected by the momentary state of the atmosphere: Fig 2 The angle of incidence 2 atmospheric depletion. The lower the solar altitude angle. Fig 1 The earth—sun relationship 1. Part of this air. Fig 3 Length of path through the atmosphere Figure 5 illustrates the distribution of incoming radiation and Figure 6 shows how the earth's surface releases heat by three processes: At the maximum heating zone which is somewhere between the tropics of Cancer and Capricorn air is heated by the hot surface.

Fig 5 Passage of radiation through the atmosphere Fig 6 Heat release from the ground and the atmosphere. These are known as North East and South Easttrade-winds [5]. The actual wind is the resultant of thermal forces and the Coriolis force Figure 8: The following explanation also relates to Figure 7. This area experiences either completely calm conditions or only very light breezes of irregular directions and is referred to by sailors as 'doldrums'.

As it is light in weight and behaves as fluid. Fig 7 Global wind pattern The area where the air rises. There is a slippage' at the boundary layer between the earth and its atmosphere caused by what is known as the 'Coriolis force'.

The global pattern of thermal air movements is shown in Figure 7. The effect is experienced as a wind blowing in a direction opposite to that of the earth's rotation. The origin of these winds was for a long time in dispute. Air at the surface moves from the coldest to the slightly warmer regions.

The northerly is deflected into north-easterly and the southerly near the South Pole into south-easterly polar winds. Air can be diverted or funnelled by mountain ranges..

A descending air mass will very rarely give any precipitation. The pattern is similar to that near the Equator. As the circumferential velocity of air at the poles is almost nil. Winds in these zones are typically light and variable. The force. Air flow deflected upwards. If it is reduced at the Equator by easterly winds. As a consequence of this annual shift most regions of the earth experience seasonal changes not only in temperature but also in wind directions and in rainfall as a result of air movements which carry water vapour.

The humidity of air will vary with the rate of evaporation of moisture from the surface below. At the meeting point of cold polar winds and the mid-latitude westerlies.

The location of the ITCZ follows the maximum solar heating. Fig 8 Wind parallelogram 1. Air movements can be generated on quite a small scale. Fig 9 Seasonal shifts of the inter-tropical convergence zone. They include averages. Climatic records as gathered at airports and meteorological stations are not primarily intended. It is the designer's task to analyse climatic information and present it in a form that allows him to identify features that are beneficial or harmful to the future occupants of his building.

These five values for each of the 12 months would give a reasonably accurate picture of temperature conditions. Alternatively a thermograph can be used. The average is taken between each day's maximum and minimum and then the average of the 30 days' average is found and possibly as many years' average for the same month.

Monthly mean maximum is the average of 30 days' maximum temperatures. The amount of moisture the air can hold the saturationpoint humidity: SH depends on its temperature see appendix 1. As a broad description. It is often necessary to supplement such information with unpublished data obtained directly from meteorological stations. The relative humidity RH is. These will establish the monthly mean range of temperatures.

It may be useful to indicate the highest and lowest temperatures ever recorded for each month. Publications frequently omit some of the aspects that interest the designer. The dry-bulb or 'true air temperature' is a value taken in the shade. Relative humidity is the ratio of the actual amount of moisture present. Readings can be taken at specified times of the day. To give an indication of diurnal variations.

Fig 10 The Stevenson screen Humidity is usually measured with the wet-and-dry-bulb hygrometer. As in dry air the evaporation is faster. Having made the two readings. The rate of evaporation. This consists of two ordinary mercury thermometers mounted side by side. The vapour pressure concept is rarely used in practical work. Relative humidity can also be expressed as the ratio of actual vapour pressure to the 'saturation point vapour pressure': Fig 11 A hygrograph Vapour pressure is measured in the standard SI pressure unit.

The relationship of all these quantities. The 'atmospheric pressure' P is the sum of the 'partial pressure of dry air' Pa and the 'partial vapour pressure' Pv: The first one measures the air dry-bulb temperature DBT.

Moisture evaporating gives a cooling effect. The bulb of the second one is covered with a gauze or wick and is kept wet. Few records exist of night-time sky conditions [11].

The maximum rainfall for any hour period is a useful guide for the predication of flooding. As the early morning values are fairly high in any climate. A single average figure giving the sky conditions for a typical day of a given month may conceal significant differences. It would be useful for the designer to know the time of day and frequency of observations. This is only possible. Ever recorded maxima and minima would give an indication of the reliability of rains or deviations from the average.

The driving rain index [10] characterises a given location and expresses the degree of exposure. On average. They are often used alone. Values indicating the total precipitation for each month of the year and as many years' average would show the pattern of dry and wet seasons.

It is the product of annual rainfall in m and the annual average wind velocity in metres per second: It is measured by rain-gauges. Obviously this index only broadly classifies the given location. Where these are not available. A variety of more sophisticated instruments solarimeter. Fig 12 Psychrometric chart Sky luminance values are needed if daylighting in buildings is to be predicted.

A 'wind-force scale' developed by Beaufort in Measurements in urban areas are often taken at a height of between 10 and 20 m to avoid obstructions. For the purposes of detailed design. It is also important for him to note the calm periods in each month. The definitions of the twelve categories are given in appendix 4. All observatories record the occurrence of storms. It is customary to tabulate winds according to their direction and velocity categories.

An anemograph can produce continuous recordings of wind velocity and directional changes.. Total radiation received over a longer period.

Appendix 3 gives a method for estimating daily radiation totals on the basis of sunshine duration records. The US Weather Bureau collects recordings of solar radiation intensity from all countries of the world.. Quantitative radiation data are not normally published by meteorological observatories. This is the instantaneous intensity. Velocities near the ground are a good deal lower than the free wind speed.

Directions can be grouped into eight or sixteen categories: Free wind velocities are normally recorded in open flat country at a height of 10 m [14]. This could be supplemented by the highest and lowest daily totals for each month.

Appendix 2 gives a series of protractors for the calculation of radiation intensities under clear sky conditions. Several methods of diagrammatic representation have been evolved. This is accomplished best by adopting a standardised method of graphic presentation. Fig 13 Monthly wind frequency graph 1. Although such events may be rare.

Discomfort — even if it impedes work or sleep — can be accepted if it is rare enough and lasts only for a few hours.

For the purposes of showing the diurnal variations of one climatic parameter e. Figure 15 illustrates a graphic method that was developed especially to facilitate environmental design. This section of the climatic survey may range from a few notes about local species of plant life to a lengthy compendium of the major native plants and trees — their shape and colour. It is necessary to sort.

The designer must classify rare events into those which affect human comfort and those which may endanger the safety of buildings and the lives of inhabitants. It is an important element in the design of out-door spaces. Structural safety.

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Although generally regarded as a function of climate. Fig 14 Annual wind frequencies Nairobi To understand a new and unfamiliar climate one must relate it to a familiar one then measure and note essential differences. Even the comparison of simplified climate graphs such as those shown in Figure 17 can reveal the most important differences.

When the two graphs are placed side by side or superimposed if one is transparent similarities and differences become apparent and characteristic features can be identified. This is best done by using the standard graphic presentation first for the climate of one's own home-town and then for the strange climate being investigated.

One zone merges gradually and almost imperceptibly into the next. Its usefulness increases with the increase of the number of people familiar with it. Boundaries of climatic zones cannot be accurately mapped. The present work concerns itself with tropical climatic zones only.

It is essential for the designer to be familiar with the character and location of these zones. It is. The basis of this classification is given by the two atmospheric factors. It has since been widely accepted and proven useful. The subdivision of tropical climates into climatic zones should be looked upon as a useful tool of communication.

It is a code that conveys a great deal of information for those who are familiar with it. Kenya — warm-humid climate. Accordingly the tropical regions of earth are divided into three. The main criterion is: Fig 19 Climate graph Phoenix. Examples of cities in this zone: Detailed description of each zone is given below many of the values taken from Atkinsons publication [15]. Figure 18 shows a climate graph for Mombasa. There is very little seasonal variation throughout the year. Quito and Pernambuco.

Spray is driven nearly. The thunder-storms are accompanied by frequent air-to. Solar radiation is partly reflected and partly scattered by the cloud blanket or the high vapour content of the atmosphere. Special characteristics: The diurnal range is rarely more than 8 degC and the annual range is only about 14 degC. When heavily overcast. Seasonal variations are negligible.

Both the diurnal and annual ranges of temperature are quite narrow. Annual rainfall can vary from to mm and may exceed mm in one month. Precipitation is high. Mosquitoes and other insects abound. Plant-supporting organic substances and mineral salts are dissolved and washed away by rain-water.

Precipitation is high throughout the year. Air temperature. Sky conditions are fairly Cloudy throughout the year. Cloud and vapour content also prevents or reduces outgoing radiation from the earth and sea to the night sky. Up to mm may fall in a single storm of a few hours' duration. The subsoil water table is usually high and the ground may be waterlogged. Organic building materials tend to decay rapidly.

Vegetation grows quickly due to frequent rains and high temperatures and it is difficult to control.

Of building climatic design housing and manual pdf tropical

There are usually one or two dominant directions. Wind velocities are typically low. Little light is reflected from the ground. The red or brown laterite soils are generally poor for agriculture.

Skies can be bright. Typical examples are the Caribbeans. Sky conditions are normally clear or filled with white broken clouds of high brightness. Sky conditions are normally clear. The soil is often dry with a fairly low water-table. Figure 19 shows a climate graph for the last.

The high salt content of the atmosphere encourages corrosion in coastal areas. Towards the end of the hot period. Clouds are few due to the low humidity of the air. The diurnal range is very great: It varies with the rainfall. The sky is usually dark blue. Examples of settlements in this zone: Alice Springs. Winds are usually local. Clear blue skies are of low luminance. Solar radiation is direct and strong during the day.

Vegetation is less luxuriant and of a lighter green colour than in the warm-humid zones. Flashstorms may occur over limited areas with as much as 50 mm rain in a few hours. Two marked seasons occur: The heating of air over the hot ground causes a temperature inversion. Much higher velocities occur during cyclones see below.

Winds are hot. Sunlight reflected from light coloured coral. Solar radiation is strong and mainly direct. Diffuse radiation is only present during dust haze periods. Ground glare can be intense. Solar radiation is strong. Kano and New Delhi. The salt laden atmosphere accelerates corrosion. Soils dry quickly after rain and would generally be fertile if irrigated. Typical examples are Kuwait.

The ground and rocks are brown or red. The soil is usually dusty and very dry. The diurnal mean range varies between 9 and 12 degC. Examples of cities with composite climates: Antofagasta and Karachi. Vegetation is sparse. Vegetation is sparse and difficult to maintain because of the lack of rain and low humidities.

Localities further north and south often have a third season. The moisture is. Two seasons occur normally. Winds are mostly local. These tend to blow off the sea towards the land during the day and in the reverse direction during the night. The high day-time temperatures and rapid cooling at. These are regarded to be amongst the most unfavourable climates of the earth. Approximately two-thirds of the year is hot-dry and the other third is warm-humid.

There are two seasons: The subsoil water-table is very low. Sky conditions are as for hot-dry desert climates. The latter is shown as an example in Figure Winds are hot and dusty during the dry period. Solar radiation alternates between conditions found in the warm-humid and the hot-dry desert climates. Sky conditions markedly vary with the seasons. There is little or no rain during the dry seasons. The intensity of sky glare varies accordingly.

Towards the end of the hot-dry seasons the sky becomes brighter with frequent dust haze. Directional changes in the prevailing winds at the beginning of the warm-humid season bring rain-clouds and humid air from the sea.

Monsoon winds are fairly strong and steady. The sky is heavily overcast and dull during the monsoons. Annual rainfall varies from to 1 mm with to mm in the wettest month. The landscape becomes green and fertile within a few days.

The soil is damp during the rains but it dries out quickly. Dust and sand-storms may occur. There is a risk of soil erosion during monsoons. Fig 20 Climate graph New Delhi — composite or monsoon climate Vegetation. Occasional condensation problems. Termites are common. In the cooler period vegetation covers the ground. Plants grow quickly. In the dry season strong ground glare may be experienced.

The diurnal range is great. It becomes more diffuse as cloud cover increases. Rain often falls in heavy concentrated showers. Strong radiation loss at night during the dry season. Mountainous regions and plateaux more than to 1 m above sea-level experience such climates.

During the monsoon rains the sky is overcast — and the clouds are heavy and low. A climate graph for Nairobi has been given in Figure Thunder-storms with a fair proportion of electric discharges — air to ground.

Sky conditions are normally clear or partly cloudy. Winds are variable. The annual range depends on latitude: Mexico City and Nairobi. Ultra-violet radiation especially is stronger than at lower altitudes. Vegetation is green although not very luxuriant during the wet season but it may wither in the dry season. Examples of cities in such regions: Addis Ababa.

Solar radiation is strong and direct during the clear periods. Hail may also occur. The soil may be damp in the rains but dries quickly. Seasonal variations are small in upland climates near the Equator. Precipitation is variable. Every city. Such information may be a useful guide to the climate of the site. Information published by the nearest meteorological observatory describes the macroclimate. It does. For the urban geographer the term 'microclimate' may mean the climate of a whole town.

The nature and extent of climatic deviations — also the likely effects of the intended building — should be assessed early in the design stage. The botanist may consider the 'microclimate' of a single plant leaf. A logical method will be to follow the sequence of climatic elements examined in the previous section and see how each of these may be affected by the above mentioned factors.

The best approach is to start with regional data and assess the likely deviations. Valuable advice may be obtained from an expert. For a large project it is certainly worthwhile to seek expert advice. Three-dimensional objects. Ground surface. The opportunity is rarely given to carry out on site observations and measurements for any length of time. The latter can imply any local deviation from the climate of a larger area. It is the purpose of the present section to give an understanding of local factors.

Factors which may cause local deviation from this are: In all cases. Cold air tends to settle in the deepest depressions and behaves as a liquid.

In calm conditions the air within 2 m of the ground remains stratified in layers of differing temperatures. Mixing of the hotter and cooler layers takes place as the heat build-up of the lowest layer becomes great enough to cause an upward eddy of warmer.

During the day. Figure 21 shows the typical diurnal changes at various heights. At night. It does not flow quite as readily as water. Heat exchange at surfaces varies between night and day. At any point near the ground the air temperature is dependent upon the amount of heat gained or lost at the earth's surface and any other surfaces with which the air has recently been in contact.

This is a much more stable situation than the 'normal' day-time temperature strata — there are no thermal forces tending to cause disturbances or upward eddies. If it flows down the hill and along the floor of a long. Fig 21 Formation of temperature inversion Topography can thus strongly influence air temperature [18]. The lowest layer of air becomes cooler. The direction of heat flow is reversed: Such an upward current may divert any horizontal air movement in an upward direction.

In an extreme case it can happen that on a large site located on the top of a hill and extending down to both slopes. A similar situation can develop over towns. With a lower RH the rate of evaporation is increased. Especially on a clear night with still air.

Where the ground changes level by more than m. The following situation is likely to arise. With the increase of height or steepness of the hill formation. The relative humidity depends as much on the air temperature as on the actual amount of water vapour present in the air. When the dewpoint temperature is reached the formation of fog will start.

Fig 22 Precipitation on hills The cause of the above phenomenon is that the hill forces the air mass to rise. At night the situation is reversed. An open surface of water or rich vegetation would provide an abundant supply of water — in such a case strong evaporation would increase the AH of the lower layers of air.

With air movement the rate of evaporation is increased. Fig 24 Driving rain parallelograms 1. Fig 23 Precipitation over towns Actually a number of workers have reported a higher frequency of rains of the cloudburst type over city centres Figure If rainfall generally occurs associated with high wind velocities. Atmospheric pollution. When the sun is on these sides. The flag-like permanent cloud on the leeward side of the Rock of Gibraltar is a good example.

A factor contributing to this. This effect is most pronounced when such obstructions lie on the east or west of the site. At mid-latitudes a site sloping towards the pole will receive much less radiation than one sloping towards the Equator 3 the daily total amount of radiation may also be influenced by the slope later sunrise and earlier sunset for a northern slope on the northern hemisphere but also by nearby hills or even trees and existing buildings.

The magnitude of thermal effects of such incident radiation will. Large stretches of water can give rise to local coastal breezes. The more pronounced the form of the valley. The type of ground cover affects the wind speed gradient. Radiation on a vertical building surface will be affected by its orientation.

The effect of long. Observations can usually reveal a pattern of their course during certain seasons of the year. In regions where wind can provide a welcome relief from sultry heat. These may be whirlwinds or local breezes. If it is vegetation. Fig 25 Wind velocity gardients. The factors under 1 and 3 above will still show an effect. Near the ground the wind speed is always less than higher up.

In addition to this. On lake shores these breezes are rarely effective beyond about m inland. On-shore breezes from water to land during the day may lower the maximum temperature by as much as 10 degC.

The day-time heating of air over barren ground often gives rise to local thermal winds. On a hilly site the greatest wind speeds will be experienced at the crests of hills.

Small valleys and depressions will normally experience low velocities. Smaller dust particles being in suspension in the air stream are carried more freely and may reach a height of 1 m or more.

Sand is only drifting along the surface even in strong winds. Both the birth and the path of such whirlwinds can depend on small-scale local features: Their effect is most adverse in positions exposed to high wind velocities.

Pdf housing and tropical manual climatic design of building

If not. Their moderating effect on the site climate has already been referred to in the context of air temperature. Local features particularly affect the accompanying electrical phenomena. Valuable information for siting and landscaping can be obtained from the observation of existing vegetation. Tops of hills are mostly subjected to lightning strikes and a tall building. By covering the ground with vegetation. It will be deposited at locations where the wind speed is reduced or where local turbulences or eddies are formed.

Macroseismic information is available everywhere and. Precautionary measures must be taken accordingly. With a working knowledge of the soil. Dust and sand-storms are influenced by local factors. They mostly occur in well-defined areas — seismic zones. At the time of maximum solar heating In all hot and dry regions of the earth the beneficial climatic effect of even the lightest plant cover is quite considerable.

Rarely will similarly reliable measured data be available for a given site. The climate graph and the values included in the tables can be changed accordingly. The presence of solid particles in urban atmosphere may assist in the formation of fog and induce rainfall under favourable conditions The extent of deviations may be quite substantial. A method summarising such data in graphic and tabulated form has been given in 1. This may be quite satisfactory. The factors causing deviations of the urban climate from the regional macro.

Such intervention with the natural environment is greatest in large towns or cities. Strong turbulences and eddies can also be set up at the leeward corners of obstructions. As the climatic parameters for a site are the same as for a region. Air temperature in a city can be 8 degC higher than in the surrounding countryside and a difference of 11 degC has been reported.

In most cases the regional data may be used with only some qualitative remarks regarding local deviations. Where such deviations are not certain. Wind velocity can be reduced to less than half of that in the adjoining open country. This is possible only when the atmosphere transfers angular momentum from the tropics and also to a much smaller extent from the polar caps to the middle latitudes.

For definition of units. Figures in square brackets refer to the bibliographical list on p. The expansion and contraction of this is transmitted through a lever mechanism to a pen.

It has been calculated [4] that if the atmosphere were still. In the easterly wind regions surface friction does indeed transfer westerly angular momentum from the earth to the atmosphere.

This is an instrument based on the moisture movement of human hair. Section 2 Comfort: The desirable conditions 2. This cycle can be and is often impeded by unfavourable climatic conditions and the resulting stress on body and mind causes discomfort. It is essential that the mind and body recovers through recreation. Accumulated sensations of well-being or discomfort contribute to our total verdict on the house in which we live and the school.

The task of the designer is to create the best possible indoor climate it is not feasible to regulate out-door conditions. The effect of climate on man. The occupants of a building judge the quality of the design from a physical as well as an emotional point of view. It is a challenge for the designer to strive towards the optimum of total comfort. Considerable information has by now been published on the physical side. To appreciate the effect of these climatic factors. Interest in establishing thermal comfort criteria dates back in Europe about years.

The following table indicates the rate of excess heat output of the body in various activities. This excess heat production varies with the overall metabolic rate. Most of the biochemical processes involved in tissuebuilding. Criteria of total comfort depend upon each of the human senses.

Activity watts Sleeping min. In the following paragraphs. Of all the energy produced in the body. Basic warmth criteria were first established in the mining. The total metabolic heat production can be divided into basal metabolism. All energy and material requirements of the body are supplied From consumption and digestion of food.

Human response to the thermal environment does not depend on air temperature alone. The physiological responses to specific climatic conditions. The processes involved in converting foodstuff into living matter and useful form of energy are known as metabolism [20]. It has been established beyond doubt that air temperature. If there is some form of simultaneous heat gain from the environment e.

Evaporation takes place in the lungs through breathing. Radiant heat loss depends on the temperature of the body surface and the temperature of opposing surfaces.

Fig 26 Body heat exchange Conduction depends on the temperature difference between the body surface and the object the body is in direct contact with. In order to maintain body temperature at this steady level.

Convection is due to heat transmission from the body to the air in contact with the skin or clothing which then rises and is replaced by cooler air. Evaporation heat loss is governed by the rate of evaporation.

Intermittent heavy lifting. The body can release heat to its environment by convection. The rate of convective heat loss is increased by a faster rate of air movement. If the vasomotor regulation is still insufficient. These may involve the change in the basal metabolic heat production. The functions of huts and houses are reduced to three: The safe storage of agricultural products receives as much — and often more — attention than shelter for human beings.

Space is plentiful. Growing family or tribal units can be accommodated easily by the addition of huts, stores and enclosures as the need arises. Waste disposal and health problems are solved, or at least mitigated, by dispersal. There are a few exceptions. In the Nile Valley, in the hinterland of Peshawar, and in parts of Bengal and southern China, for instance, land is so fertile and so much in demand that villagers have to be as careful in its use as townsfolk.

Yet in most rural communities, the land needs for housing are negligeable compared to those of agriculture. The traditional building forms of the rural tropics often include sound solutions of climatic problems. Given technological limitations and the always overriding considerations of safety, some of these solutions must be considered ingenious, and there can be no doubt that they deserve careful study. Yet the most pressing housing needs of the tropics are urban, and traditional forms because of their origin in the life and economy of rural societies are seldom suited to urban conditions.

This is demonstrated convincingly by going through the above-described features of rural life and noting how few of them apply in towns and cities.

Building materials for city needs cannot be taken from the surrounding countryside without, in the case of organic materials, denuding it of vegetation or, in the case of earth building, making borrow pits of dangerous dimensions. Building materials that have to be brought in over large distances cease to be cheap. The rhythm of city life does not include time for house building, least of all for the poorest, the unemployed, the casual or unskilled labourer who has to fight hard to stay alive and who cannot afford to miss a chance of finding a foothold in the urban economy.

Even time for maintenance work becomes scarce and the townsman soon learns to value durable materials and methods that do not need frequent attention. He receives money for his labour and is His family, like that of the villager, spends a good part of the day in the open, but space for outdoor living is not as plentiful and suitable.

Safe storage of possessions is even more important than in the open country. So is privacy, but both are more difficult to achieve. Yet it is space, a commodity so plentiful and so little valued in rural life, that becomes a major concern for the town-dweller.

It is not a matter of the total amount of land available - although that too can be a problem in certain urban areas - but rather a question of location. Because he wants to be near to, work, schools and shops, the townsman must be content with a small piece of ground and adjust his life style, household size and building methods to proximity with others. Proximity makes major issues out of problems that the villager can afford to neglect.

Fire hazards, waste disposal, sanitation, and noise pollution are typical urban problems that cannot be solved by going back to essentially rural traditions. They cannot be solved either by the adoption of Western technology and Western patterns that have their origin in different climates, different cultures and different economic conditions.

Housing climatic design building manual pdf and of tropical

It seems so obvious that house types and building materials from cold climates cannot solve the problems of cities where heat is the dominant problem and that solutions from communities with average per capita incomes of S7 per annum cannot work in communities where the income is less than S Yet the cities of the tropics are full of galvanised iron roofs, plate glass windows and buildings that could just as well stand in Manchester, Detroit or Montreal.

The resulting urban environment is climatically and socially inadequate. A wealthy elite can escape the consequences of poor design through mechanical air- conditioning. The others suffer from living conditions that permit neither efficient work nor rest or enjoyment.

It is the purpose of this manual to demonstrate that this need not be so, that it is possible to create cities that have pleasant indoor and outdoor living spaces and are suited to the social conditions of their inhabitants. Section 1 Climate: A somewhat more scientific definition is: Before tropical climates can be examined in detail, we must survey the factors shaping the climates, on a global scale. The earth receives almost all its energy from the sun in the form of radiation, thus the sun is the dominating influence on climates.

According to human means of perception we can distinguish: The spectral energy distribution varies with altitude, due to the filtering effect of the atmosphere.

Some of the shorter wavelengths are absorbed by the atmosphere and reradiated at much longer wavelengths, e. As the luminous efficiency of energy-radiation depends on its spectral composition, there is no constant relationship between radiation intensity and its lighting effect.

The earth moves around the sun in a slightly elliptical orbit. One revolution is completed in days, 5 hours, 48 minutes and 46 seconds. This orbit results from the gravitational pull of the sun and the centrifugal force due to the earth's inertia and momentum.

At aphelion the solar distance is million km and at perihelion is is million km. The axis of this rotation the line joining the North and South Poles is tilted to the plane of the elliptical orbit, at an angle of Maximum intensity is received on a plane normal to the direction of radiation. If the axis of earth were rectangular to the plane of the orbit, it would always be the equatorial regions which are normal to the direction of solar radiation.

Due to the tilted position, however, the area receiving the maximum intensity moves north and south, between the tropic of Cancer latitude This is the main cause of seasonal changes. On 21 June areas along latitude At the same time latitude On 21 March and 23 September areas along the Equator are normal to the sun's rays and experience a zenith path of the sun. For all areas of the earth these are the equinox days day and night of equal length. Figure 1 clearly explains this relationship.

Fig 1 The earth—sun relationship 1. Figure 2 shows how the same amount of radiation is distributed over a larger area, therefore less radiation alls on unit area. Fig 2 The angle of incidence 2 atmospheric depletion, i.

The lower the solar altitude angle, the longer the path of radiation through the atmosphere, thus a smaller part reaches the earth's surface. Figure 3 indicates this geometrical relationship and Figure 4 shows this effect in quantitative terms for points at different heights above sea-level.

This atmospheric depletion is also affected by the momentary state of the atmosphere: Fig 3 Length of path through the atmosphere Figure 5 illustrates the distribution of incoming radiation and Figure 6 shows how the earth's surface releases heat by three processes: At the maximum heating zone which is somewhere between the tropics of Cancer and Capricorn air is heated by the hot surface, it expands, its pressure is decreased it becomes lighter, it rises vertically and flows off at a high level towards colder regions.

Part of this air, having cooled down at the high level, descends to the surface in the subtropic regions, from where the cooler, heavier air is drawn in towards the Equator from both north and south. Fig 5 Passage of radiation through the atmosphere Fig 6 Heat release from the ground and the atmosphere Fig 7 Global wind pattern The area where the air rises, where these northerly and southerly winds meet, where the tropical front is formed, is referred to as the inter-tropical convergence zone ITCZ.

This area experiences either completely calm conditions or only very light breezes of irregular directions and is referred to by sailors as 'doldrums'. The global pattern of thermal air movements is shown in Figure 7. The following explanation also relates to Figure 7. As it is light in weight and behaves as fluid, held against the earth's surface only by gravity and friction, it has a tendency to lag behind the earth's rate of rotation where this rotation is the fastest, i.

There is a slippage' at the boundary layer between the earth and its atmosphere caused by what is known as the 'Coriolis force'. The effect is experienced as a wind blowing in a direction opposite to that of the earth's rotation. The actual wind is the resultant of thermal forces and the Coriolis force Figure 8: These are known as North East and South Easttrade-winds [5], a term originated by round the world traders in the days of sailing-ships.

Fig 8 Wind parallelogram 1. Winds in these zones are typically light and variable. The origin of these winds was for a long time in dispute, but it is now generally agreed that the mid-latitude westerlies can best be explained by the law of conservation of angular momentum.

If it is reduced at the Equator by easterly winds, this must be compensated for by westerly winds elsewhere. The pattern is similar to that near the Equator. Air at the surface moves from the coldest to the slightly warmer regions, i. As the circumferential velocity of air at the poles is almost nil, the air will lag behind the rotating earth as it moves away from the poles. The northerly is deflected into north-easterly and the southerly near the South Pole into south-easterly polar winds.

At the meeting point of cold polar winds and the mid-latitude westerlies, a band of low pressure — a subpolar front — is formed, with highly variable and strong winds. The location of the ITCZ follows the maximum solar heating, i. As a consequence of this annual shift most regions of the earth experience seasonal changes not only in temperature but also in wind directions and in rainfall as a result of air movements which carry water vapour. The force, direction and moisture content of air flows are strongly influenced by topography.

Air can be diverted or funnelled by mountain ranges. Air flow deflected upwards, as it cools, releases its moisture content. A descending air mass will very rarely give any precipitation, therefore rainfall characteristics vary sharply between locations on windward and leeward slopes of mountain ranges. The humidity of air will vary with the rate of evaporation of moisture from the surface below, i.

Air movements can be generated on quite a small scale, e. Fig 9 Seasonal shifts of the inter-tropical convergence zone They include averages, changes and extremes of temperature, the temperature differences between day and night diurnal range , humidity, sky conditions, incoming and outgoing radiation, rainfall and its distribution, air movements and special features, such as trade-winds, thunder-storms, dust-storms and hurricanes.

Climatic records as gathered at airports and meteorological stations are not primarily intended Publications frequently omit some of the aspects that interest the designer. It is often necessary to supplement such information with unpublished data obtained directly from meteorological stations. It is the designer's task to analyse climatic information and present it in a form that allows him to identify features that are beneficial or harmful to the future occupants of his building.

The dry-bulb or 'true air temperature' is a value taken in the shade, the thermometer being mounted inside a louvred wooden box, known as the 'Stevenson screen Figure 10 , at a height of 1. Readings can be taken at specified times of the day, or if a maximum—minimum thermometer is used, one reading daily can give the momentary temperature as well as the maximum and minimum temperatures reached in the past 24 hours. Alternatively a thermograph can be used, which is based on a bimetallic thermometer and gives a continuous graphic recording of temperature variations.

As a broad description, monthly mean temperatures can be given for each of the 12 months. The average is taken between each day's maximum and minimum and then the average of the 30 days' average is found and possibly as many years' average for the same month. To give an indication of diurnal variations, this can be supplemented by monthly mean maxima and minima. Monthly mean maximum is the average of 30 days' maximum temperatures. These will establish the monthly mean range of temperatures.

It may be useful to indicate the highest and lowest temperatures ever recorded for each month, i. These five values for each of the 12 months would give a reasonably accurate picture of temperature conditions, on which the design work can be based see Section 8. The relative humidity RH is, however, a much more useful form of expression, as it gives a direct indication of evaporation potential.

The amount of moisture the air can hold the saturation- point humidity: SH depends on its temperature see appendix 1. Relative humidity is the ratio of the actual amount of moisture present, to the amount of moisture the air could hold at the given temperature — expressed as a percentage: Fig 10 The Stevenson screen Humidity is usually measured with the wet-and-dry-bulb hygrometer.

This consists of two ordinary mercury thermometers mounted side by side. The first one measures the air dry-bulb temperature DBT. The bulb of the second one is covered with a gauze or wick and is kept wet. Moisture evaporating gives a cooling effect, thus the reading of the wet-bulb temperature WBT will be less than the DBT.

As in dry air the evaporation is faster, the cooling is more pronounced and the difference between the two readings the 'wet-bulb depression' is greater. The rate of evaporation, thus the wet-bulb depression, is a function of the relative humidity. Having made the two readings, the corresponding RH can be found from the psychrometric chart Figure 12 , from a table or a special slide-rule see appendix 1.

The 'atmospheric pressure' P is the sum of the 'partial pressure of dry air' Pa and the 'partial vapour pressure' Pv: Relative humidity can also be expressed as the ratio of actual vapour pressure to the 'saturation point vapour pressure': The vapour pressure concept is rarely used in practical work.

The relationship of all these quantities, i. This is only possible, where continuous hygrograph4 recordings are available. Where these are not available, readings are made just before sunrise, e.

As the early morning values are fairly high in any climate, the afternoon values are much more characteristic of a given location.

They are often used alone, as a brief indication of humidity conditions. It is measured by rain-gauges, i. Values indicating the total precipitation for each month of the year and as many years' average would show the pattern of dry and wet seasons. Ever recorded maxima and minima would give an indication of the reliability of rains or deviations from the average.

The driving rain index [10] characterises a given location and expresses the degree of exposure. It is the product of annual rainfall in m and the annual average wind velocity in metres per second: Obviously this index only broadly classifies the given location, the actual rain penetration will depend on the instantaneous rain intensity and the simultaneous wind velocity.

On average, two observations are made per day, when the proportion of sky covered by cloud is expressed as a percentage some records give cloud cover in 'tenths' or even in 'eighths' or 'octets', e. Few records exist of night-time sky conditions [11]. It would be useful for the designer to know the time of day and frequency of observations.

A single average figure giving the sky conditions for a typical day of a given month may conceal significant differences, e. Fig 12 Psychrometric chart Sky luminance values are needed if daylighting in buildings is to be predicted. A variety of more sophisticated instruments solarimeter, heliometer, actinometer and pyranometer are used for the quantitative recording of solar radiation, but reliable and comparable data is few and far between.

This is the instantaneous intensity, i. This could be supplemented by the highest and lowest daily totals for each month, to set the limits of variations which can be expected.

Quantitative radiation data are not normally published by meteorological observatories, but are sometimes available on request or can be found in special publications [13]. The US Weather Bureau collects recordings of solar radiation intensity from all countries of the world. Appendix 2 gives a series of protractors for the calculation of radiation intensities under clear sky conditions, to be used in conjunction with the stereographic sun- path diagrams.

Appendix 3 gives a method for estimating daily radiation totals on the basis of sunshine duration records. An anemograph can produce continuous recordings of wind velocity and directional changes.

Free wind velocities are normally recorded in open flat country at a height of 10 m [14]. Measurements in urban areas are often taken at a height of between 10 and 20 m to avoid obstructions. Velocities near the ground are a good deal lower than the free wind speed.

Directions can be grouped into eight or sixteen categories: A 'wind-force scale' developed by Beaufort in , based on visual observation, is still in use in spite of its completely unscientific nature. The definitions of the twelve categories are given in appendix 4. It is also important for him to note the calm periods in each month. All observatories record the occurrence of storms, hurricanes, typhoons or tornadoes. It is customary to tabulate winds according to their direction and velocity categories, in terms of their frequency of occurrence, over a significant time, generally 25 to 50 years.

Several methods of diagrammatic representation have been evolved, some of which re shown in Figures 13 and Fig 13 Monthly wind frequency graph 1. Although such events may be rare, it is important to extract from meteorological data their frequency, likely duration and nature. The designer must classify rare events into those which affect human comfort and those which may endanger the safety of buildings and the lives of inhabitants.

Discomfort — even if it impedes work or sleep — can be accepted if it is rare enough and lasts only for a few hours. Structural safety, on the other hand, must be guaranteed however infrequent the danger. Although generally regarded as a function of climate, vegetation can in its turn influence the local or site climate. It is an important element in the design of out-door spaces, providing sun- shading and protection from glare.

This section of the climatic survey may range from a few notes about local species of plant life to a lengthy compendium of the major native plants and trees — their shape and colour, also their preferred orientation and situation. It is necessary to sort, summarise and simplify available data with reference to the objectives and requirements of climatic design. This is accomplished best by adopting a standardised method of graphic presentation.

Figure 15 illustrates a graphic method that was developed especially to facilitate environmental design. For the purposes of showing the diurnal variations of one climatic parameter e. Fig 14 Annual wind frequencies Nairobi To understand a new and unfamiliar climate one must relate it to a familiar one then measure and note essential differences.

This is best done by using the standard graphic presentation first for the climate of one's own home-town and then for the strange climate being investigated. When the two graphs are placed side by side or superimposed if one is transparent similarities and differences become apparent and characteristic features can be identified.

Even the comparison of simplified climate graphs such as those shown in Figure 17 can reveal the most important differences. Fig 15 Climate graph Nairobi — tropical upland climate Fig 16 Temperature isopleths Fig 17 Comparison of climates However, certain zones and belts of approximately uniform climates can be distinguished. It is essential for the designer to be familiar with the character and location of these zones, as they are indicative of the climatic problems he is likely to encounter.

Boundaries of climatic zones cannot be accurately mapped. One zone merges gradually and almost imperceptibly into the next. It is, nevertheless, easy to identify the zone, or the transition area between two zones, to which a particular settlement belongs. The present work concerns itself with tropical climatic zones only, as defined in 1. The subdivision of tropical climates into climatic zones should be looked upon as a useful tool of communication.

It is a code that conveys a great deal of information for those who are familiar with it. Its usefulness increases with the increase of the number of people familiar with it, who accept and use it. It has since been widely accepted and proven useful.

The basis of this classification is given by the two atmospheric factors The main criterion is: Accordingly the tropical regions of earth are divided into three, major climatic zones and three subgroups: Fig 19 Climate graph Phoenix, Arizona - hot-dry desert climate 2 Hot-dry desert, or semi-desert climate - subgroup: Detailed description of each zone is given below many of the values taken from Atkinsons publication [15].

Examples of cities in this zone: Figure 18 shows a climate graph for Mombasa. There is very little seasonal variation throughout the year, the only punctuation being that of Air temperature, i.

Both the diurnal and annual ranges of temperature are quite narrow. Humidity, i. Precipitation is high throughout the year, generally becoming more intense for several consecutive months. Annual rainfall can vary from to mm and may exceed mm in one month, the wettest month. Sky conditions are fairly Cloudy throughout the year. Solar radiation is partly reflected and partly scattered by the cloud blanket or the high vapour content of the atmosphere, therefore the radiation reaching the ground is diffuse, but strong, and can cause painful sky glare.

Cloud and vapour content also prevents or reduces outgoing radiation from the earth and sea to the night sky, thus the accumulated heat is not readily dissipated. Wind velocities are typically low, calm periods are frequent, but strong winds can occur during rain squalls.

There are usually one or two dominant directions. Vegetation grows quickly due to frequent rains and high temperatures and it is difficult to control. The red or brown laterite soils are generally poor for agriculture. Plant-supporting organic substances and mineral salts are dissolved and washed away by rain-water. The subsoil water table is usually high and the ground may be waterlogged.

Little light is reflected from the ground. Special characteristics: Organic building materials tend to decay rapidly. Mosquitoes and other insects abound. The thunder-storms are accompanied by frequent air-to- air electrical discharges. Typical examples are the Caribbeans,the Philippines and other island groups in the Pacific Ocean.

Seasonal variations are negligible. The diurnal range is rarely more than 8 degC and the annual range is only about 14 degC.

Precipitation is high, 1 to 1 mm per annum, and to mm in the 27 wettest month. Up to mm may fall in a single storm of a few hours' duration. Spray is driven nearly Sky conditions are normally clear or filled with white broken clouds of high brightness, except during storms, when the skies are dark and dull.

Solar radiation is strong and mainly direct, with a very small diffuse component when the sky is clear, but varies with the cloud cover.

Much higher velocities occur during cyclones see below. Vegetation is less luxuriant and of a lighter green colour than in the warm-humid zones.

It varies with the rainfall.

Manual of tropical housing and building / O.H. Koenigsberger[et al.] - Details - Trove

Sunlight reflected from light coloured coral, sand and rock can be very bright. The soil is often dry with a fairly low water-table. The high salt content of the atmosphere encourages corrosion in coastal areas. Examples of settlements in this zone: Assuan, Baghdad, Alice Springs, and Phoenix.

Figure 19 shows a climate graph for the last- named. Two marked seasons occur: The diurnal range is very great: Flash- storms may occur over limited areas with as much as 50 mm rain in a few hours, but some regions may not have any rain for several years. Sky conditions are normally clear. Clouds are few due to the low humidity of the air. Solar radiation is direct and strong during the day, but the absence of cloud permits easy release of the heat stored during the day-time in the form of long-wave radiation towards the cold night sky.

Diffuse radiation is only present during dust haze periods. Winds are usually local. The heating of air over the hot ground causes a temperature inversion, and as the lower warm air mass breaks through the higher cooler air, local whirlwinds are often created.

Winds are hot, carrying dust and sand — and often develop into dust-storms. Vegetation is sparse and difficult to maintain because of the lack of rain and low humidities.

The soil is usually dusty and very dry. Soils dry quickly after rain and would generally be fertile if irrigated. The subsoil water-table is very low. The high day-time temperatures and rapid cooling at- night may cause materials to crack and break up.

These are regarded to be amongst the most unfavourable climates of the earth. Typical examples are Kuwait, Antofagasta and Karachi. There are two seasons: The diurnal mean range varies between 9 and 12 degC, the larger diurnal variation occurring during the cool season. The moisture is, however, not precipitated but remains suspended in the air, creating intensely uncomfortable conditions. Precipitation, as in other desert regions, is very low.

Sky conditions are as for hot-dry desert climates, a little more cloud may occur in the form of a thin, transparent haze, which is likely to cause glare. Solar radiation is strong, with a higher diffuse component than in desert climates, due to the thin clouds and suspended moisture. Winds are mostly local, coastal winds, caused by the unequal heating and cooling of land and sea surfaces. These tend to blow off the sea towards the land during the day and in the reverse direction during the night.

Vegetation is sparse, not more than some dry grass. The ground and rocks are brown or red; it is dry and dusty throughout the year. Ground glare can be intense. The salt laden atmosphere accelerates corrosion. Examples of cities with composite climates: The latter is shown as an example in Figure Two seasons occur normally.

Approximately two-thirds of the year is hot-dry and the other third is warm-humid. Localities further north and south often have a third season, best described as cool-dry. DBT, in the shade is as follows: Annual rainfall varies from to 1 mm with to mm in the wettest month. There is little or no rain during the dry seasons. Sky conditions markedly vary with the seasons. The sky is heavily overcast and dull during the monsoons, and clear, with a dark blue colour, in the dry seasons.

Towards the end of the hot-dry seasons the sky becomes brighter with frequent dust haze. The intensity of sky glare varies accordingly. Solar radiation alternates between conditions found in the warm-humid and the hot-dry desert climates.

Winds are hot and dusty during the dry period. Directional changes in the prevailing winds at the beginning of the warm-humid season bring rain-clouds and humid air from the sea. Monsoon winds are fairly strong and steady. Fig 20 Climate graph New Delhi — composite or monsoon climate Vegetation, which is sparse — characteristic of a hot-dry region — with brown and red barren ground, changes rapidly and dramatically with the rain.

The landscape becomes green and fertile within a few days. Plants grow quickly.