Converting Dry Bulb and Wet Bulb Temperatures to Fahrenheit

When dealing with temperature measurements in meteorology and environmental science, it's often necessary to convert between different temperature scales. This guide explains how to convert dry bulb and wet bulb temperatures from Celsius to Fahrenheit using simple formulas.

Understanding Dry Bulb and Wet Bulb Temperatures

Dry bulb temperature (DBT) refers to the ambient air temperature as measured by a thermometer. Wet bulb temperature (WBT) is the temperature of air when it passes over a water-saturated cloth or wick. The wet bulb temperature is usually lower than the dry bulb temperature, with the exact difference depending on the humidity of the air.

Conversion Formulas

Converting temperatures from Celsius to Fahrenheit can be done using the following formula:

Fahrenheit °F Celsius °C × 9/5 32

Example Conversion

Let's take an example to illustrate the conversion:

Dry Bulb Temperature: If the dry bulb temperature is 25°C, the conversion to Fahrenheit is as follows:

DBT °F 25 × (9/5) 32 77°F

Wet Bulb Temperature

For the wet bulb temperature, let's consider 20°C:

WBT °F 20 × (9/5) 32 68°F

Summary of Conversions

For the given temperatures:

Dry Bulb Temperature (25°C): 77°F Wet Bulb Temperature (20°C): 68°F

If you have specific temperatures in Celsius that you need to convert, feel free to provide them, and I can help with the calculations!

Understanding the Differences

Phil suggested using examples to get a feel for the differences between dry bulb and wet bulb temperatures. This understanding is crucial for various meteorological applications.

The dry bulb temperature should reflect the air temperature, while the wet bulb temperature will be the same or lower. At 100% relative humidity, the wet bulb and dry bulb temperatures will be the same. However, as relative humidity decreases, the difference between the two temperatures also decreases.

The wet bulb temperature is closely related to the dew point temperature. The dew point is the temperature at which moisture in the air condenses into dew. The wet bulb temperature typically correlates well with the dew point, given adequate air circulation around the wet bulb thermometer.

At low humidity, the wet bulb temperature can be very close to the dew point, making it a useful indicator of air moisture content. In conditions of high humidity, especially in coastal areas, the difference between the wet bulb and dry bulb temperatures can be quite significant.

In dry, hot climates such as in Tucson during the summer when the humidity is close to zero and the air temperature is around 110°F (43°C), the difference between dry bulb and wet bulb temperatures can be substantial. Under these conditions, the wet bulb temperature might be around 90°F (32°C), leading to a difference of approximately 20 to 30 degrees Fahrenheit.

For a more detailed comparison, you can find tables converting dew point to relative humidity at different temperatures. This information is particularly useful in environmental research, agriculture, and HVAC applications.

Conclusion

Converting dry bulb and wet bulb temperatures from Celsius to Fahrenheit is straightforward using the provided formulas. Understanding these differences is crucial for various applications, from meteorology to climate control.