This document provides an overview of environmental control systems and climate components. It defines climate as average weather over a long period of time, determined by natural and human factors. Key natural elements that influence climate are described as the atmosphere, geosphere, hydrosphere and biosphere, while human land and resource uses also impact climate. Specific climate factors discussed include latitude, seasons, altitude, water effects, and atmospheric circulation. Different climate regions across the world are also outlined.

1. Environmental Control Systems-1
Climate and its Components
Lecture-1
PROF. DR. SYED TAUSEEF AHMAD,
DEPARTMENT OF ARCHITECTURAL ENGINEERING & DESIGN,
UNIVERSITY OF ENGINEERING & TECHNOLOGY, LAHORE, PAKISTAN

2. NATURAL ENVIRONMENT
Space
Sun
earth
RESOURCE ENVIRONMENT
Atmosphere
Land
Vegetation
water
BUILT ENVIRONMENT
Buildings
Industry
Transport
Service

4. Introduction
• The earth's climate is generally defined as the
average weather over a long period of time. A
place or region's climate is determined by both
natural and anthropogenic (human-made)
factors.
• The natural elements include the atmosphere,
geosphere, hydrosphere, and biosphere, while
the human factors can include land and resource
uses.
• Changes in any of these factors can cause local,
regional, or even global changes in the climate.

5. How does climate differ from weather?
• Weather is the current atmospheric
conditions, including temperature, rainfall,
wind, and humidity at a given place. Weather
is what's happening right now or is likely to
happen tomorrow or in the very near future.
• Climate, on the other hand, is the general
weather conditions over a long period of
time.

6. The climate of a region can be linked to
certain factors which are listed below;
Geographical Latitude
Season of the year
Altitude and Topography
Effects of water
Atmospheric circulation

7. Latitude
• The geographical latitude of a place on Earth is a measure of
its position above or below the equator.
– Intensity of solar radiation decreases as latitude increases.

8. SEASON OF YEAR
The orbit of the earth
around the Sun is slightly
elliptical in shape and
the axis of the earth is
tilted by 23.5° with
respect to plane that
passes through the Sun
and the Equator. The tilt
causes the change in
radiation, length of day,
and climate between
summer and winter.

9. ALTITUDE AND TOPOGRAPHY
• The height of a place
above sea level affects
its climate because the
temperature of the air
decreases with
altitude.
• Air temperature drops by
6.5°C for each 1000
meters increase in
altitude.

10. EFFECTS OF WATER
Large masses of water over surface of the earth
have a considerable effect on climate, both locally
and globally.
Oceans and large lakes affect climates by reducing
the extremities of air temperature at places nearby.

11. ATMOSPHERIC CIRCULATION
• The movement of large masses of air in the
atmosphere influence climate by producing winds
that distribute heat and moisture.
Atmospheric circulation driven by uneven heating of the Earth by the Sun

12. World Climate Regions
The same climate definitions are used world-wide. Differentiated climate
impacts the types of buildings that are appropriate (or not!).

13. CLIMATIC REGIONS
• Hot and Arid Zone
The regions, where mean daily maximum dry bulb
temperature is 38oC or higher and relative humidity of 40%
or less prevail during the hottest month of the year and
where the altitude is not more than 500m above Mean Sea
Level (M.S.L), may be classified as hot and arid zones.
Hot and Humid Zone
The regions, where mean daily maximum dry bulb
temperature is above 32oC and relative humidity above 40%
prevail during the hottest month of the year and where the
altitude is not more than 500m above Mean Sea Level
(M.S.L), may be classified as hot and humid zones.

14. • Warm and Humid Zone
The regions, where mean daily maximum dry bulb
temperature is 26oC to 32oC and relative humidity of 70% or
above prevail during the hottest month of the year and
where altitude is not more than 100m above Mean Sea Level
(M.S.L) may be classified as warm and humid zones.
Cold Zone
The regions where mean daily minimum dry bulb
temperature is 6oC or less prevail during the coldest month
of the year and where the altitude is more than 1200m
above Mean Sea Level (M.S.L), may be classified as cold
zones.

15. GLOBAL WARMING
There is considerable scientific evidence to suggest that the
activities of humans are causing the current increase in
global temperature.
The effects of global warming will change the ecology of
many parts of the earth and bring difficulties for people
living there. Possible effects of global warming include the
following;
melting of polar ice causing rise in sea levels and disappearance of
land.
increase in severity of storms and flooding.
change in rainfall patterns, forming new deserts
changes in ocean currents, causing changes in local climates
changes in patterns of snowfall and ice sheets .

16. GREEN HOUSE EFFECT
The greenhouse effect is a warming of the earth’s
lower atmosphere which trap solar energy. The
principle greenhouse gasses are;
Carbon dioxide
Methane CH
Nitrogen Oxide
Chlorofluorocarbons

17. COMPONENTS OF CLIMATE
• Temperature of air
• Humidity of the air
• Sky conditions and the amount of direct
solar radiation.
• Amount of rainfall and
• Air movement and prevailing wind
direction.

18. Air Temperature
• The temperature of the air or Dry Bulb
Temperature (D.B.T.) is the temperature
measured in the shade and is recorded at one or
two meters above the ground surface by a
mercury thermometer in degree Celsius.
• It is important to know the mean maximum and
mean minimum daily air temperatures for each
month of the year. These are the mean of the
highest and lowest air temperatures of each day
of every month, averaged again by the number
of the years for which recordings are available.

19. Relative Humidity
• The humidity of the air is the amount of water
contained as vapor in the air.
• It can be expressed as absolute humidity, which
is the moisture content of the air in terms of
grams of water per kilogram of dry air.
• However, a much more useful expression is
relative humidity, which is the water content of
the air as a percentage of the maximum amount
of water that the air could hold at that
temperature at which the reading is made.

20. Air Movement
• Air movement and prevailing wind directions
are usually recorded in terms of the average of
daily or monthly changes in wind direction in
degrees and speed in meters per second.
• Usually data of air movement are recorded ten
meters above an open ground (often the local
airport); but different topographical conditions,
vegetation and buildings can reverse the
prevailing wind direction and change its velocity
as it affects a particular site.

21. Sky Conditions
• Sky conditions are usually described in terms
of the proportion of the sky covered by
cloud, averaged over the days of each month
and again over the number of years for which
records have been maintained.
• This may be recorded twice a day (morning
and afternoon) as percentages, tenths or
eighths of the hemisphere of the sky.

22. Precipitation
The amount of rainfall or precipitation is usually
recorded as the average mm/day or mm/month and
this gives a useful indication of seasonal changes.
Often, average maximum rainfall in 24 hours or the
average number of days in which a certain amount
(say 2.5 cm.) of rain has fallen is also provided.
This information is useful as an indicator of the
intensity of rain, which will influence the design of
openings, roofs, gutters, etc.

23. Any
Questions?