ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria BASIC CONCEPTS ON CLIMATE ARC 810: BUILDING CLIMATOLOGY DEPARTMENT OF ARCHITECTURE FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria SUB - TOPICS 1.1Movement of the earth around the sun 1.2Solar time 1.3Solar radiation 1.4Global wind pattern 1.5Spatial systems of climate 1.6Design with climate

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1. INTRODUCTION To understand some basic concepts in Building Climatology, some preliminary knowledge of science is needed. Therefore, this course aims to unify students’ different backgrounds and perceptions of basic concepts especially on global climate.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria INTRODUCTION (cont’d) The following will be discussed:  The motion of the earth and how it gives rise to various seasons.  Various ways of measuring time.  How the distribution of solar radiation affects climate.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria INTRODUCTION (cont’d)  The genesis of the global wind pattern.  The spatial and time scales used to delineate categories of climate.  Design with climate.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN The earth makes one rotation along its north - south axis in 24 hours which leads to day and night and it makes one revolution in 365 days, 5 hours, 48 minutes and 46 seconds.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d) The earth's north-south axis inclination to the plane of orbit at 23 degrees and 27 minutes leads to different seasons.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d) The movement of the Sun can be said to be between the tropic of cancer (23.5 degrees North) and the tropic of capricon (23.5 degrees South).

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d)  Summer solstice: This happens in June when the Earth is tilted towards the sun and the tropic of cancer receives maximum intensity of solar radiation. Summer is experienced in the Northern hemisphere.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d)  Winter solstice: When the Earth is tilted towards the sun and the tropic of capricon receives maximum intensity of solar radiation. Winter is experienced in the Northern hemisphere.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d)  Vernal equinox and Autumnal equinox: When the day and the night have equal length for all places on Earth. It happens in March and September when the sun crosses the equator.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.1 MOVEMENT OF THE EARTH AROUND THE SUN (cont’d) The day is longer than the night during the summer with the reverse in winter. A section through the sun, the ecliptic plane and the earth in two directions.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) The following four terms are usually used in discussing solar time: ‑ clock time ‑ mean solar time ‑ true solar time ‑ local apparent time (LAT)

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  CLOCK TIME Time shown by a time piece. The world is divided into time zones. Each of the 24 hours of the day has a time zone. All part of each time zone has the same clock time irrespective of the longitude.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) MEAN SOLAR TIME A uniform time indicated by a clock which does not take the equation of time into consideration. In a particular time zone, the mean solar time and the clock time are the same on the reference longitude.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) Location Mean Solar Time Correction Factor on the reference longitude West Earlier4 minutes to be added East Later4 minutes to be subtracted MEAN SOLAR TIME

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) MEAN SOLAR TIME Worked Example Determine the mean solar time for Lagos (3:24 degrees East), the reference longitude for Nigeria is 15 degrees East, given a clock time of 12noon and a reference longitude of 15 degrees East.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) MEAN SOLAR TIME Worked Example The correction factor: = 4 (15 - 3:24) minutes. = 4 x 11:36 minutes. = 46:24 minutes. Lagos is to the West of the reference longitude, therefore mean solar time: = 12: :46:24 = 11:13:36.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  TRUE SOLAR TIME The time in which noon occurs when the sun is due South, as shown by a sundial. Equation of time: This is the correction applied to the mean solar time to obtain the true solar time. It may be positive or negative.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  TRUE SOLAR TIME Worked Example Obtain the true solar time for Maiduguri (13:05 degrees East) on January 15th given a clock time of 12 noon. To obtain the mean solar time, time difference: = 4 ( :05) minutes. = 4 (1:55). = 7:40 minutes.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  TRUE SOLAR TIME Worked Example To obtain the mean solar time, time difference: = 4 ( :05) minutes. = 4 (1:55). = 7:40 minutes. Mean solar time: = 12: :07:40. = 11:52:20.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  TRUE SOLAR TIME Worked Example Mean solar time: = 12: :07:40. = 11:52:20. The equation of time on January 15 is +9 minutes: True solar time is therefore: The equation of time on January 15 is +9 Mins

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d)  TRUE SOLAR TIME Worked Example True solar time is therefore: = 11:52: :09:00 = 12:01:20.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.2 SOLAR TIME (cont’d) This term is used in astronomical and nautical calculations and is equivalent to the true solar time.  LOCAL APPARENT TIME

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d) Earth’s main source of energy comes from the Sun and comes in form of electromagnetic radiation. Heat flow rate is measured in Watts (W), in Joules per second (J/S). The speed of light (c) = frequency (v) X wavelength (Lambda)

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d) Frequency = No. of oscillations per second, measured in Hertz. Wavelength = Distance between identical points of two succeeding oscillations, measured in unit length.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  SPECTRUM OF SOLAR RADIATION This can be broadly divided into 3 sections with wavelength extending from 290 to 2300 nanometres: i. Ultraviolet radiation ( nm) ii. Visible light ( nm) iii. Infra-red radiation ( nm)

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT The intensity of solar radiation reaching the upper surface of the atmosphere. It has a value of 1395 W/m. Slight variations may occur in this value due to changes in the sun and distance between the earth and the sun.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Atmospheric depletion of solar radiation The absorption of solar radiation by ozone, vapours and dust particles in the atmosphere. Not all the solar radiation reaching the upper surface of the atmosphere get to the earth's surface as a result of this.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Atmospheric depletion of solar radiation The absorption of solar radiation by ozone, vapours and dust particles in the atmosphere. Not all the solar radiation reaching the upper surface of the atmosphere get to the earth's surface as a result of this.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d) ATMOSPEHRIC DEPLETION OF SOLAR RADIATION

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d) The purity of the atmosphere affects the amount of radiation absorbed. The greater the quantity of ozone, dust, smoke, vapours, etc. in the atmosphere, the less radiation reaches the surface of the Earth.  THE SOLAR CONSTANT

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d) Cosine Law of Solar Radiation The intensity of solar radiation on a tilted surface equals the normal intensity times the cosine of the angle of incidence.  THE SOLAR CONSTANT

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT To maintain the thermal balance of the Earth, the equivalent amount of the radiation absorbed is lost back to outer space. Without this regulatory system the temperature of the Earth would constantly be on the increase.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Incoming Radiation If the total amount of solar radiation reaching the outer surface of the earth is 100%, 20% is reflected from clouds 25% is absorbed in the atmosphere 5% is reflected from the ground 50% of the total radiation is absorbed by the Earth's surface.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Incoming Radiation 23% of the 50% being in the form of diffuse radiation and the remaining 27% as direct solar radiation. This energy is absorbed by the hydrosphere to raise water temperature, by the bare soil and by land and marine vegetation.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Incoming Radiation

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.3 SOLAR RADIATION (cont’d)  THE SOLAR CONSTANT Outgoing Radiation The Earth loses the heat absorbed through Longwave radiation (40%) Evaporation (40%) Convection (20%)

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN The global wind pattern is the result of 3 basic forces.  Thermal force  Coriolis force  Force explained by law of conservation of angular momentum

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d)  Thermal Force Is a result of the differential radiation balance on the surface of the earth. The difference in temperature between the equator and the poles gives rise to convection currents.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d) Inter-Tropical Convergence Zone (ITCZ) The area where the hot air rises, between the tropics of Cancer Capricon. This is where the northerly and southerly winds meet, forming the Tropical Front.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d)  The Corollis Force The Coriolis force is caused by the apparent higher speed of rotation of the equator than the poles.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d) The Coriolis force and the thermal force create a resultant force in the form of a wind. This is the North-East trade wind in the Northern Hemisphere and the South-East trade wind in the southern hemisphere

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d) Westerly Winds They are strong winds blowing between latitudes 30 and 60 degrees. But unlike the trade-winds, they blow in the same direction as that of the earth's rotation.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d) The Polar Winds They are created by thermal forces and the lag of air behind the rotating earth. These forces create easterly winds known as the north- easterly and south-easterly polar winds.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.4 GLOBAL WIND PATTERN (cont’d) Origin of the North East and South East trade winds.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE The concept of scale is very important in building climatology. There are 4 generally recognised categories of climate based on spatial and time scales: - The global climate. - The regional macroclimate. - The (local) topoclimate. - The microclimate.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE (cont’d) The concept of scale is very important in building climatology. There are 4 generally recognised categories of climate based on spatial and time scales: - The global climate. - The regional macroclimate. - The (local) topoclimate. - The microclimate.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE (cont’d) The Global Climate This is a result of the movement of air masses due to temperature and pressure changes. This climate is largely independent of surface topography.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE (cont’d) The Regional Macroclimate Changes in land features and surface change have an effect on the regional macroclimate. The Topoclimate or Local Climate The effect of the topography and human activity play a very important role on this.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE (cont’d) The Microclimate The microclimate refers to a spatial scale of about 1 km horizontally and 100 m vertically. The architect is primarily interested in the microclimate which is affected by trees, buildings and windflow patterns.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.5 SPATIAL SYSTEMS OF CLIMATE (cont’d) Spatial Systems of Climate

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.6 DESIGN WITH CLIMATE This has been a major consideration in Architecture. Various research has been carried out to determine the relationship between climate and architecture and to formulate guides for architects in the different climates.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.6 DESIGN WITH CLIMATE (cont’d) The harsh desert climate also dictated interesting architectural solutions. The main problems are high day temperatures accompanied by intense insolation, low night temperatures, dust and strong winds.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.6 DESIGN WITH CLIMATE (cont’d) The use of thick mud walls and mud roofs provides the necessary thermal capacity. This is combined with compact courtyard design and small openings.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria 1.6 DESIGN WITH CLIMATE (cont’d) Examples of adaptation to climate can also be found in Nigeria. The use of verandas in the southern part of the country provides shade from the tropical sun.

ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria THANK YOU.