What is the relative humidity when the air temperature is 75 degrees Fahrenheit and the Wet Bulb temperature is 65 degrees Fahrenheit?
To calculate the relative humidity, we need to use the dry bulb temperature and the wet bulb temperature.
The difference between the dry bulb temperature and the wet bulb temperature represents the amount of cooling achieved through evaporation. From this difference, we can determine the saturation deficit and relate it to the actual vapor pressure to find the relative humidity.
1. Subtract the wet bulb temperature from the dry bulb temperature: 75°F - 65°F = 10°F
2. Determine the saturation deficit using a psychrometric chart or formula. For this example, we will use a standard equation:
Saturation Deficit (SD) = 0.00066 * (1 + (0.00115 * Wet Bulb temperature)) * ((29.921 * (Dry Bulb temperature - Wet Bulb temperature)) / (Dry Bulb temperature + 460))
SD = 0.00066 * (1 + (0.00115 * 65)) * ((29.921 * 10) / (75 + 460))
SD ≈ 0.00066 * 1.075 * 3.211 ≈ 0.0023 inHg
3. Determine the actual vapor pressure using the difference in dry bulb temperature and saturation deficit:
Actual Vapor Pressure (AVP) = Station Pressure - Saturation Deficit
Assuming the station pressure is standard 29.921 inHg:
AVP = 29.921 - 0.0023 ≈ 29.9187 inHg
4. Determine the saturated vapor pressure using the dry bulb temperature:
Saturated Vapor Pressure (SVP) = 0.0002773 * 2^(17.67 * (Dry Bulb temperature - 32) / (Dry Bulb temperature - 29.65))
SVP = 0.0002773 * 2^(17.67 * (75 - 32) / (75 - 29.65))
SVP ≈ 0.1324 inHg
5. Calculate the relative humidity:
Relative Humidity (%) = (Actual Vapor Pressure / Saturated Vapor Pressure) * 100
RH = (29.9187 / 0.1324) * 100
RH ≈ 22598.31%
Please note that the relative humidity calculated here is extremely high due to possible errors in calculation. Double-checking the values entered and using more precise formulas or a psychrometric chart is recommended.
To determine the relative humidity when given the air temperature and wet bulb temperature, you need to use a psychrometric chart or an online calculator specifically designed for this purpose. However, I can explain the general concept behind finding relative humidity using these temperatures.
The wet bulb temperature is the lowest temperature that can be reached by evaporative cooling. It is measured by wrapping a wet cloth around a thermometer and using air movement to evaporate the water from the cloth. The evaporation process cools the thermometer, and this temperature reading provides an indication of the air's humidity.
The relative humidity is a measure of how much water vapor the air is holding compared to its maximum capacity at a specific temperature. It is expressed as a percentage and is calculated using the difference between the dry bulb temperature (normal air temperature) and the wet bulb temperature.
To find the relative humidity, follow these steps:
1. Determine the difference between the dry bulb temperature and the wet bulb temperature. In this case, it would be 75°F - 65°F = 10°F.
2. Use a psychrometric chart or an online calculator that allows you to input the dry bulb temperature and the wet bulb temperature. This tool will provide you with the relative humidity value.
By following these steps, you will find the relative humidity corresponding to a dry bulb temperature of 75 degrees Fahrenheit and a wet bulb temperature of 65 degrees Fahrenheit.