How do you determine the difference between the Wet-Bulb and Dry-bulb Temperatures?

The difference between the wet-bulb and dry-bulb temperatures is known as the wet-bulb depression. Here's how you can determine it:

1. Measure the Dry-Bulb Temperature: This is the ambient air temperature measured by a regular thermometer exposed to the air but shielded from radiation and moisture.

2. Measure the Wet-Bulb Temperature: This is the temperature a parcel of air would have if it were cooled to saturation (100% relative humidity) by the evaporation of water into it, with the latent heat being supplied by the parcel. It is measured by a thermometer that has its bulb wrapped in cloth—kept wet with distilled water—and is then whirled around in the air for a few minutes (or air is blown over the cloth).

3. Subtract the Wet-Bulb Temperature from the Dry-Bulb Temperature: The difference between these two temperatures is the wet-bulb depression. This value can be used to determine relative humidity and dew point temperature.

Remember, the wet-bulb temperature will always be less than or equal to the dry-bulb temperature. The wet-bulb depression is larger in dry air and smaller in moist air.