Instruments for measuring temperature and Relative humidity

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1. STUDY OF TEMPERATURE AND HUMIDITY MONITORING INSTRUMENTS Presenter: Manish Kumar pal ENT-07M-2017 Agriculture and Forestry university Rampur, Chitwan 5 th March,2019

2. Temperature   It is a physical quantity expressing hot and cold. It is measured with a thermometer calibrated in one or more  temperature scales.  Celsius scale  ( centigrade ) (denoted °C )  Fahrenheit scale (denoted °F )   Kelvin scale(denoted K ) Relative humidity It is the amount of water vapor (%) present in the atmosphere compared to total amount air it can hold at a given temperature If relative humidity is 100% then precipitation is occurring 5 th March 2019

3. Temperature Measuring instruments Instantaneous thermometer A lso called as Ordinary mercury-In-Glass Thermometer. Is used far instantaneous determination of temperature . Gives only maximum air temperature at the time of reading. C an be accurately recorded only if the bulb of thermometer is protected from sun. 5 th March 2019

4. Temperature Measuring cont … Totalizer thermometer It is a special U-shaped thermometer with maximum on the left and minimum on the right side mounted on a board. Graduated both centigrade and farenheight, that is highly desirable for measuring the temperature over a period of time. The maximum temperature is reached during day and minimum temperature during the night . 5 th March 2019

5. Relative Humidity measuring instruments Psychrometer (dry and wet bulb thermometer) It consists of two ordinary thermometers fixed to a board. The bulb of one is open to the air that records the temperature under the dry condition T he bulb of other is wrapped with a piece of a cotton wick for the purpose of wetting and recording temperature under wet condition. As the water from the wick evaporates, it cools the bulb thus lowering the reading of the wet bulb thermometer. The rate of evaporation depends upon the dryness of the air. Therefore , the greater the fall in wet bulb thermometer, the drier is the air. A reference to conversion table about the fall in temperature at any given atmospheric temperature also gives the relative humidity . 5 th March 2019

6. 6 Psychrometer Parts: Dry Bulb Thermometer Wet Bulb Thermometer Reservoir and Stocking WET DRY 5 th March 2019

7. Relative Humidity cont …… 5 th March 2019