two thermometers—one wet-bulb and one dry-bulb—
to determine humidity through evaporation
.
What is wet bulb temperature used for?
Wet bulb temperature essentially
measures how much water vapor the atmosphere can hold at current weather conditions
. A lower wet bulb temperature means the air is drier and can hold more water vapor than it can at a higher wet bulb temperature.
What is the difference between a wet and dry bulb thermometer?
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.
How do you use a dry bulb thermometer?
Set the thermometers in front of the fan as before. After 5 minutes record the “wet bulb” temperature reading and the “dry bulb” temperature reading. 4. To determine relative humidity subtract the lower “wet bulb” temperature from the higher “dry bulb” temperature to determine the difference and compare to the chart.
What are the uses of dry-bulb thermometer?
dry-bulb thermometer A
thermometer that registers normal air temperature
. It may be used in conjunction with a wet-bulb thermometer: the relative humidity can be found by measuring the depression of temperature registered by the wet bulb. See also hygrometer and psychrometer.
What is wet bulb temperature in simple words?
Wet bulb temperature is
the lowest temperature to which air can be cooled by the evaporation of water into the air at a constant pressure
. It is therefore measured by wrapping a wet wick around the bulb of a thermometer and the measured temperature corresponds to the wet bulb temperature.
What does wet bulb tell you?
The wet-bulb temperature is defined as the
temperature of a parcel of air cooled to saturation (100% relative humidity) by the evaporation of water into it
, with the latent heat supplied by the parcel. A wet-bulb thermometer indicates a temperature close to the true (thermodynamic) wet-bulb temperature.
Why is it called wet bulb?
The term wet bulb comes from a way the measurement can be taken,
by wrapping a piece of wet cloth around the end of a thermometer to see how much evaporation can decrease the temperature
. “The idea here is that you and I are essentially wet bulbs,” Schneider said.
What is the other name for wet and dry bulb thermometer?
The wet and dry bulb thermometer is therefore also known as
the wet and dry bulb hygrometer
, since the hygrometer is the instrument used for measuring the humidity.
When the difference between the readings of wet and dry bulb is low the relative humidity is?
When the air is saturated with water vapor, then the water on the wet bulb cannot evaporate. Therefore, there is little difference in the temperature readings of the dry and wet bulbs of the psychrometer. In other words, the relative humidity is
100%
.
What happens when wet bulb temperature rises?
(The wet bulb changes temperatures slower than the dry bulb, so as temperature increases, the
dry bulb temperature increases faster
. Therefore, the greater the temperature, the greater the wet bulb depression.)
What does it mean when wet bulb and dry bulb are the same?
The wet bulb temperature is always lower than the dry bulb temperature but will be identical
with 100% relative humidity
(the air is at the saturation line). Combining the dry bulb and wet bulb temperature in a psychrometric diagram or Mollier chart, gives the state of the humid air.
What is a dry bulb thermometer?
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 is an example of a wet bulb thermometer?
A wet bulb thermometer is simply a
regular mercury thermometer whose bulb is covered with wet fabric
, usually muslin, that is dipped in a reservoir to keep it wet.
Why is wet bulb important?
The wet bulb temperature is
crucial for the design and dimensioning of a cooling tower
. A cooling tower cools water by evaporation to temperatures that are lower than the ambient temperature and that approach the wet bulb temperature.
