# Dry Bulb Temperature and Wet Bulb Temperature

Dry Bulb Temperature and Wet Bulb Temperature related concepts its application and Frequently asked questions enclosed here

### Frequently asked questions regarding this

What is dry bulb temperature and wet bulb temperature? why we measure it?
What is Relative Humidity and Dew point? How to calculate it?

### Dry Bulb Temperature [DBT]

Dry bulb temperature is an ambient air temperature which is directly measured by thermometer it is not affected by moisture contained by air.

### Wet Bulb Temperature [WBT]

Wet bulb temperature is adiabatic saturated temperature which is measured by thermometer with wet cloth wrapping and continuous air flow

Wet bulb temperature is used for find out Relative Humidity

If relative humidity is 100% then wet bulb temperature and dry bulb temperature will be same.

#### How to find relative humidity?

Set thermometer assembly and ensure working condition of it.

Check wet bulb cloth wrapping which must be continuous wet with continuous air flow.

Wet bulb temperature =12°C
Dry bulb temperature = 22°C

Then
ΔT = DBT - WBT
= 22 - 12
= 10°C

Air Pressure = 101.325 Pa

P = 101.325 exp(-0.0001184Elv)
= 101.325

Conversation factor A
A = 0.00066 ( 1.0 + 0.00115 Twb)
= 0.00067

Now we will find Saturated vapour pressure at Wet Bulb Temperature.

= 1.403

Calculate the vapour pressure of the partial pressure of water vapour

= 0.7242

Calculate Saturated Vapour Pressure Esdb

= 2.646

Relative Humidity = 100 * Ed / Esdb

= 27.3

Dew point also calculated with Wet Bulb Temperature and Dry Bulb Temperature

### Dry bulb temperature and wet bulb temperature apparatus

Wikipedia

Photo credits

Dry Bulb Temperature and Wet Bulb Temperature
Dry Bulb Temperature and Wet Bulb Temperature appratus
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