Download WIND MEASURING AND HUMIDITY SENSORS.

WIND MEASURING AND HUMIDITY SENSORS.
Presented by:
GROUP THREE
Olabiwonnu Abimibola Oladunni ARC/05/5628
Akinluyi Temitope Oyindamola
ARC/05/5588
Adebiyi Olufemi Adeyinka
ARC/04/3160
Course:
ENVIRONMENTAL CONTROL: CLIMATE
(ARC309)
Lecturers-in-charge:
Prof. O.O. Ogunsote MNIA
Arc. J.J. Adam
MARCH, 2008
TABLE OF CONTENT
1.0
INTRODUCTION
1.1
WINDS AS A CLIMATIC FACTOR
1.1.1 Types of Wind
1.2
HUMIDITY AS A CLIMATIC FACTOR
2.0 WIND MEASUREMENT
2.0.1 Instruments used for measuring wind and its limitations
3.0 HUMIDITY SENSOR
3.0.1 Types of humidity sensor and its limitations
4.0 RECOMMENDATIONS
5.0 CONCLUSION
6.0 REFERENCES
WIND MEASURING AND HUMIDITY SENSOR
1.0
INTRODUCTION.
There is no how climatic condition will be discussed without some references to wind
and humidity as one of the climatic factors.
Wind and humidity are climatic factors related to the current in air and dealings with
moisture in the atmosphere respectively. Wind measuring is the way wind is being measured
with the aid of mechanical device while humidity sensor is a device that responds to humidity
stimulus.
1.1
WINDS AS A CLIMATIC FACTOR.
Wind is one of the manifestations of nature that catches the imagination of human. It is
produced by differences in atmospheric pressure which are primarily attributable to difference
in temperature. Variations in the distribution of pressure and temperature are caused largely
by unequal distribution of heat from the sun, together with differences in the thermal
properties of land and ocean surface. When the temperature of adjacent regions become
unequal, the warmer air tends to rise and flow over the colder, heavier air. Winds initiated in
this way are usually greatly modified by earth’s rotation.
Wind is the term used for air in motion and is usually applied to the natural horizontal
motion of the atmosphere, although one cannot see the wind. It is a common observation that
the flow is quite complex and turbulent in nature. There is a sudden variation in wind speed
called gustiness or turbulence, which plays an important part in determining building
oscillation.
1.1.1 Types of Wind
Winds are of great value in the design of buildings. It can be classified into three major
types which are:

Prevailing winds

Seasonal winds

Local winds
Wind measurement is classified as instrument use for measuring wind.
Humidity sensor is a device that responds to humidity stimulus.
Prevailing Winds: It is surface air moving towards the low pressure belt which
are called trade wind. This is responsible for Northeast trade wind and Southwest trade
wind.
Seasonal Winds: These are movement of air caused by variations in pressure
difference e.g. the monsoons of China Sea and the Indian Ocean.
Local Winds: These are those associated with the regional phenomenon and
include whirlwinds, mainly caused by daily changes in temperature and pressure
generating local effect in winds. The variations in the speed of prevailing and seasonal
winds are referred to as FLUCTUATIONS in mean velocity while variation in the local winds
is referred to as GUST.
GRAPHICAL REPRESENTATION OF THE THREE TYPES OF WIND.
1.2
HUMIDITY AS A CLIMATIC FACTOR
Humidity is a measure of the dampness of the atmosphere, which varies greatly from
place to place at different time of day. Humidity is specified on several different ways. The
actual amount of water vapour present in the air expressed in g/m 3 is called absolute humidity.
Humidity moisture content of the atmosphere is determined by the changes in temperature.
For example when the atmosphere is saturated with water; the level of discomfort is high
because the evaporation of perspiration, with its attendant cooling effect, is impossible. Also, if
air expands or contracts, its absolute humidity changes but its specific humidity do not.
In addition, Relative humidity given in weather reported is the ratio between the actual
water vapour content of the air and the total vapour content of air at the same temperature
saturated with water vapour, expressed in percentage. When it reaches 100%, the air is said to
be at due point.
When Relative humidity is high; air is moist as in the equatorial region and when
Relative humidity is low, air is dry as in desert.
In conclusion, Wind and humidity has been classified as climatic factors due to its effect
on climate.
2.0 WIND MEASUREMENT
Wind had a multiple significance, which included their beneficial effects on the climate
and fertility of plants and animals, as well as their violent, storm-producing nature.
Instruments used for measuring wind include:
 Beaufort Wind Scale.
The Beaufort Scale is a system of recording wind velocity (speed) devised in 1806 by Francis
Beaufort (1774–1857). It is a numerical scale ranging from 0 for calm to 12 for a hurricane.
Sailors and forecasters use the Beaufort Wind Scale as a standardized way to rate wind speed.
The scale, when originally drawn up, categorized wind not by its speed but by its observable
effects. Various attempts have been made since to apply precise speeds to the Beaufort ratings.
Beaufort
Scale No
Wind Description
0
Calm
1
Light air
Sped (m.p.h)
Less than 1
1-3
Effects( a guide to observation)
Smoke rises vertically
Wind direction shown by smoke-drift but
not by wind-vanes
2
Slight breeze
4-7
Wind felt on face, leaves, rustle, vanes
moved by wind.
3
Gentle breeze
8-12
Leaves & twigs in constant motion;
winds extend light flags.
4
Moderate breeze
13-18
Raises dust and loose paper; small
branches moved.
5
Fresh breeze
19-24
Small trees in leaf begin 2 sway; crested
wavelets from on inland water.
6
Strong breeze
25-31
Large branches in motion whistling heard
in telegraphy wires.
7
Moderate gale
32-38
Whole
tree
in
motion;
walking
trees;
progress
inconvenienced.
8
Fresh gale
39-46
Twigs
broken
off
generally impeded.
9
Whole gale
47-54
Slight structural damage occurs, chimney
pots removed.
10
Whole gale
55-63
Considerable structural damage tress
uprooted.
11
Storm
64-75
Widespread
damage,
very-rarely
experienced
12
Hurricane
More than 75
Widespread devastation experienced only
in tropical area.
It is the best guide used to deal with wind strengths in moving object.
 Anemometer
Wind has both speed and direction, the instrument for measuring speed of wind is
anemometer while the instrument for direction of wind is wind vane or weather cock.
Anemometer is not accurate due to the fact that the rotation of instrument continues after
the wind has abated.
 Cardinal points
Another method is the use of cardinal points
Identification of winds using only the cardinal points of wind direction is an
unimaginative, although more practical form of references.
 Probabilistic approach
This is the mathematical calculation of wind speed. It is when the speed of wind is
considered to vary with return periods.
Gust pressure= p’
Mean pressure= p
Therefore p1= p’ + p
GRAPHICAL REPRESENTATION OF PROBABILISTIC APPROACH.
3.0 HUMIDITY SENSOR
Types of Humidity Sensor
 Hygrometer
It is a type of instrument used to measure atmospheric humidity. A simple form of
hygrometer, used in houses and offices, utilizes the change in length in an organic fiber (often a
single human hair) brought about by the absorption of moisture. This type of hygrometer gives
only an approximate indication of humidity and is not used for accurate, quantitative
determinations.
 Psychrometer or Wet-And-Dry Bulb Thermometer
It is an instrument most commonly used in laboratories to measure relative humidity. It
consists of two similar thermometers that are mounted side by side i.e. one dry and one wet).
The dry bulb is exposed to the atmosphere and the wet bulb is wrapped in “Muslin” and
immersed in water to serve as wick. This type of instrument gives a quiet accurate value of
humidity.
 Dew-Point Hygrometer
It is another instrument for measuring relative humidity by means of the dew point. A small
amount of ether is placed in a highly, polished, thin, metallic cup and the evaporation of the
ether, accelerated by blowing air through it, lowers the temperature of the cup. When the dew
point of the surrounding air is reached, a film of moisture suddenly appears on the surface of
the cup. The temperature is read by means of a thermometer, and a table accompanying the
instrument for data collection. This instrument gives the relative humidity in terms of the
atmospheric and dew-point temperature.
In conclusion as relative humidity is directly related to the temperature of the air, it affects
the nature and types of cloud formation and precipitation.
4.0 RECOMMENDATION
It is obvious that architecture can not be complete without climatology. Therefore we will
suggest as a group that the planning committee should not stamp any drawings without putting
into consideration the climatic factor (especially the wind and humidity factor) of the site or
place.
5.0 CONCLUSION
Wind and Humidity as climatic factors are significant in general view because they are like
determining factors before some things such as designs of structure can be done. Measuring of
wind helps in having a good design as an architect in the sense that it helps in knowing about
building orientation, roof geometry, type of roof to be used, etc .It even helps in zoning i.e.
where the private and public areas should be sited so as to have a maximum comfort in building
design.
Humidity can not be underestimated because it also gives detail about atmospheric
moisture i.e. it gives an insight to kinds of building that are fit for a particular area.
In conclusion both wind and humidity are part of climate determinant before any work
can be done on climatology.
6.0 REFERENCES
 WIND AND EARTHQUAKE RESISTANT BUILDINGS
STRUCTURAL ANALYSIS AND DESIGN BY BUNGALE S.TARANATH Ph.D.,S.E
 INTEGRATED DESIGN SERVICES,INC. BY IRVINE, CALIFORNIA.
 PHYSICAL AND HUMAN GEOGRAPHY BY GOHCHEN LONG
 MICROSOFT ® ENCARTA ® 2006. © 1993-2005 MICROSOFT CORPORATION