Earth Science

Can anyone help?

Why is a wet-bulb and dry-bulb temperature inaccurate when using the psychrometer in a temperature that is below zero degrees Celcius or thirty-two degrees Fahrenheit?

I really want to include this information in a lab I'm typing up. Thank you.

This is an utter guess, but I'm thinking that anything that uses liquid water in below freezing temperatures would have trouble due to the freezing of the water.

Thank you for your help.