Hygrometers are handy tools for measuring humidity, but their numbers can be confusing if you don’t know what to look for. Most devices display relative humidity (RH) as a percentage, often alongside temperature readings.
What to Look For
- Percentage (%): This is RH, showing how full the air is with moisture relative to its capacity at the current temperature.
- Temperature: Usually displayed nearby, it’s crucial because RH depends on temperature.
- Dew Point: Some devices show this too—the temperature at which dew forms, helping you anticipate condensation.
Why It Matters for Astronomy
High RH (above 70%) means your telescope lenses and camera sensors are at risk of dew, which can blur images and damage equipment. Use your hygrometer readings to decide when to use dew shields or heaters.
Remember to keep your hygrometer calibrated and placed away from heat sources for accurate readings.