The other bulb is wrapped in a cotton wick or gauze.

A standard psychrometer drawing should clearly label the following four parts:

Below the wet bulb, sketch a small cup or tube. Draw a line extending from the wick into this cup to show how the water travels.

Note that this formula is an approximation and may not be accurate for all conditions.

If you are sketching this for a school project or a technical manual, follow these steps to ensure accuracy: