dry bulb vs wet bulb
Liam Parker
Updated on May 28, 2026
The dry bulb temperature is the ambient air temperature that is measured by regular thermometers, while the wet bulb temperature is measured by thermometers that are wrapped in wetted wicks. The greater the wet bulb depression, the greater the felt effect is on the discharge air temperature.
What is wet and dry bulb used for?
An instrument to measure the dew point, relative humidity, and vapor pressure. The dry-bulb thermometer shows the current temperature, whereas the wet-bulb thermometer shows a somewhat lower temperature, the result of the latent heat of evaporation, which depends on the relative humidity of the air.
What is difference between DBT and WBT?
The wet bulb temperature of the air is always less than the dry bulb temperature of air. The difference between the DBT and WBT is called as wet bulb depression.
Can wet bulb equal dry bulb?
At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature); at lower humidity the wet-bulb temperature is lower than dry-bulb temperature because of evaporative cooling.
Can wet-bulb be higher than dry-bulb?
A wet bulb thermometer measures the extent of cooling as moisture dries from a surface (evaporative cooling). The wet bulb temperature is always lower than the dry bulb temperature except when there is 100% relative humidity, making the wet bulb temperature a more accurate measurement of product temperature.
What is RH humidity?
Put simply, relative humidity (RH) is a measure of the water vapor content of air. More explicitly, it is the amount of water vapor present in air expressed as a percentage (%RH) of the amount needed to achieve saturation at the same temperature.
What is wet bulb temperature in simple words?
The Wet Bulb temperature is the temperature of adiabatic saturation. This is the temperature indicated by a moistened thermometer bulb exposed to the air flow. Wet Bulb temperature can be measured by using a thermometer with the bulb wrapped in wet muslin.
What is Kata thermometer?
The kata thermometer is a heated-alcohol thermometer; the time it takes to cool is measured and used to determine air current. It is useful for measuring low speeds in studies of air circulation.
Which is higher WBT or DBT?
Wet bulb temperature (WBT or tw):
When air is passed over the wet wick, moisture contained in the wick evaporates and cooling effect is produced at the bulb. Hence WBT is always less than DBT for unsaturated air and is equal to DBT for saturated air. WBT value is affected by moisture content of air.
What is the difference between liberty and WBT called?
The wet bulb depression is the difference between the dry-bulb temperature(Air temperature) and the wet-bulb temperature.
What is DBT WBT and DPT?
Dew point temperature (DPT): It is the temperature when the condensation of moisture begins. Dry bulb temperature (DBT): It is the temperature of moist air measured by ordinary thermometer. Wet bulb temperature (WBT): It is the temperature of air shown by thermometer whose bulb is covered with wet cloth.
Why do wet and dry bulb temperatures differ?
The rate of evaporation from the wet bandage on the bulb, and the temperature difference between the dry bulb and wet bulb, depends on the humidity of the air. The evaporation is reduced when the air contains more water vapor.
Is dry-bulb the same as temperature?
The dry-bulb temperature (DBT) is the temperature of air measured by a thermometer freely exposed to the air, but shielded from radiation and moisture. DBT is the temperature that is usually thought of as air temperature, and it is the true thermodynamic temperature.
What determines the dew point temperature?
The dew point is affected by humidity. When there is more moisture in the air, the dew point is higher. When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed via deposition rather than condensation.
What is DBT and RH?
At 100% Rh, the three characteristics DBT (Dry Bulb Temperature), WBT (Wet Bulb Temperature) & DPT (Dew Point Temperature) are.