What is needed to determine the Relative Humidity (RH)?

Relative Humidity (RH) is defined as the ratio of the actual water vapor content in the air to the maximum possible water vapor content at a given temperature. To calculate RH:

Dry bulb temperature (DBT): the ambient air temperature.

Wet bulb temperature (WBT): the temperature measured by a thermometer covered with a wet wick, influenced by evaporative cooling.

Using DBT and WBT, the humidity ratio and dew point can be determined with a psychrometric chart or Mollier diagram. From there, RH is calculated as:

A black text on a white background AI-generated content may be incorrect.

Options A and B are incomplete, while option C is an experimental method, not standard practice. The recognized method is option D.