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 Wind Description Sped (m.p.h) Effects( a guide to observation) Scale No

0 Calm Less than 1 Smoke rises vertically

1 Light air 1-3 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 inconvenienced.

8 Fresh gale 39-46 Twigs broken off trees; progress 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