Barometers Realm

1. Hygrometer scale:

   • At the bottom of the device, there is a dial with a single graduated scale showing relative humidity, expressed as a percentage (%). The scale starts at 0% (on the left) and goes up to 100% (on the right).
   • The dial features curved lines, marked in green, which help account for temperature correction. These lines indicate the dew point (denoted by the Greek letter "τ") and allow for an accurate interpretation of humidity readings depending on the current temperature.

2. Thermometer:

   • Above the dial, there is a glass mercury thermometer that measures temperature in degrees Celsius (°C). This is important for adjusting the humidity readings, as the air's capacity to hold moisture varies with temperature.
   • For example, at higher temperatures, the air can hold more moisture, so it is necessary to account for the current temperature to obtain accurate relative humidity data.

3. Using the lines on the dial:

   • The lines on the scale represent curves that indicate the dew point for different temperatures. First, the user checks the thermometer to determine the current temperature. Then, using the hygrometer dial, they find the intersection of the humidity pointer with the corresponding temperature curve to determine the dew point.
   • For example, if the thermometer shows 20°C, the user needs to find the line corresponding to that temperature and, at its intersection with the hygrometer pointer, can determine the exact value of the relative humidity and dew point.

Thus, this hygrometer combines humidity and temperature scales to provide precise measurements and includes temperature corrections to accurately determine the relative humidity of the air and the dew point.