Look inside
a sensor.

Imagine Elena setting up a connected greenhouse controller. She needs a damp air warning, so she starts with a capacitive humidity sensor. Before trusting a high reading beside the mist nozzle, she wants to understand both the sensing film and the readout. A thin moisture sensitive film sits between two electrodes. As the film absorbs water, its capacitance rises. That changing capacitance is the physical signal behind the humidity report. Relative humidity compares the moisture in the air with the maximum at that temperature, so temperature compensation belongs in the measurement. For a numerical readout check, Elena uses the chapter's D H T twenty two module timing. This module reports temperature and humidity and requires at least two seconds between reads. Working that into a polling rate, one divided by two gives at most half a read per second. She spaces the requests accordingly. Her misconception was that a very high report beside a mist nozzle must be trustworthy. Liquid water can saturate a humidity package. She must check its condensation limits and recovery before trusting that report. The takeaway is to connect the moisture sensitive film to a temperature compensated reading, while respecting timing and condensation limits.