That might be because of humidity. But what is humidity? Humidity is a measure of how much water there is in the air. Not liquid waterlike rain, invisible water in the form of a gas called water ...

Bosch has introduced a four-in-one mems sensor that measures air pressure, humidity and temperature, aa well as detecting volatile organic compounds, volatile sulfur compounds (indicating bacteria), ...

A capacitor type of hygrometer is usually used to measure relative humidity. The sensor has a dielectric polymer layer that absorbs water molecules from the air through a thin metal electrode.