Humidity
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Two thresholds and a clock
A rig at 82 and holding is a different animal from one that was at 74 twenty minutes ago. Nothing measures a slope, so two thresholds and the gap between them are how you read one.
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Same water, one night or one winter
The water on the window this morning and the mold behind the mattress in February are the same water, arriving at different speeds. One sensor at the glass predicts tonight; a cheap multipack in the cold corners predicts the winter.