Dear student,

Dry Bulb: It is the ambient temperature. Dry Bulb Temperature is a air temperature measurement measured by thermometer.

Wet Bulb: It is the lowest temperature where at constant pressure, air can be cooled by evaporation of water into atmosphere. Wet Bulb Temperature is used to know at a current weather condition how much water vapour can be hold by atmosphere.

The difference between these two is the measure of air humidity.

I hope this information was helpful to you.

Good Luck!!