Humidity is the amount of water vapor in the air. It is measured using a device called a hygrometer, which comes in both analog and digital forms. There are several methods to measure humidity, including:

• Hygrometer: This is the most common and accurate method to measure humidity. It measures both humidity and temperature and is easy to use as a simple thermometer.

• Ice Cube Method: This method involves putting two to three ice cubes in a glass of water and waiting for four minutes. If condensation forms or drips on the outside of the glass, the humidity levels may be too high. If there is no condensation forming at all, then the humidity levels may be too low.

• Wet and Dry Bulb Method: This method involves using two thermometers, one wrapped with a wet cotton ball and the other left as is. After leaving the thermometers side-by-side on a piece of cardboard for five minutes, the difference in temperature between the two thermometers can be used to calculate the relative humidity.

• Psychrometer: This is a type of hygrometer that uses two thermometers, one with a wet wick and the other dry. The difference in temperature between the two thermometers can be used to calculate the relative humidity.

Accurate humidity measurements are important across industries since water vapor above certain levels can lead to condensation and eventually corrosion or mold.