Hygrometers are devices used to measure humidity, and are often mounted inside pipe tobacco fresh. Because tobacco leaves can crack, tear and lose their flavour if not kept in an environment with a certain amount of moisture in the air, hygrometers are critical to their preservation.
These devices, sometimes called psychrometers, can also be used to monitor your outdoor environment as well as a wine-cellar, greenhouse or other area that may need to be kept at a particular temperature and dew point.
Calibration
It is relatively easy for hygrometers to become inaccurate, whether it is due to delicate design features, movement during shipping or simply with the progression of time. Thus, it's important to calibrate your hygrometer yearly. To find out an easy way to calibrate your model, check out this step by step guide at About.com.
