How is the Kestrel Wet Bulb measured without a wick?

The question is interesting... after all, Kestrel products are small, lightweight, and extremely accurate, but there is no wick... nothing wet to measure...

Our answer from the engineer:

A direct wet bulb temperature measurement is done with a mercury thermometer with a wetted wick on the end. This measurement was primarily used to estimate the relative humidity using psychrometric charts. The charts were also a function of dry bulb temperature and elevation (pressure).

In any of the Kestrel products with temperature, humidity, and pressure, we can do the reverse method to determine wet bulb. To be more precise, we use an Advanced Weather Interactive Processing System (AWIPS) method based on station pressure, dew point temperature, and dry bulb temperature.