The concept of humidity for Digital Humidity Temperature meter:

Scientists often use relative humidity to describe the amount of moisture in the air. Simply put, imagine the air as a towel. If you pour a glass of water, you can soak up the water with a towel. But in fact, a towel can actually absorb more water than a glass. Maybe he can absorb five to ten glasses of water. The amount of moisture that the air holds is only a fraction of what the air can hold, so relative humidity is a percentage. When the relative humidity is one hundred percent, the air is saturated. Like a wet towel, the air can no longer hold moisture. Evaporation and deposition are in equilibrium when the relative humidity is one hundred percent and the air is saturated. Reaching equilibrium again illustrates the increased amount of evaporation, as moisture precipitates.

Water vapor in the air is called humidity. Because the molecules of water vapour are so small that they cannot be seen, people who study humidity have developed creative ways to measure the amount of water vapour.

Digital Temperature Humidity Meter Hygrometer High Accuracy Home Indoor Outdoor Thermometer Gauge Pyrometers Tester -20-60 degree