Final answer:
The ideal relative humidity for a home is between 30-50%. Relative humidity changes with temperature because warm air can hold more water vapor. When temperature increases while the water vapor density stays the same, the relative humidity decreases.
Step-by-step explanation:
The recommended relative humidity for a home is between 30-50%. This is important for maintaining comfort as well as protecting wooden furniture, electronics, and avoiding mold growth. A moisture or humidity gauge can be used to monitor humidity levels at home. To increase humidity, one can use a vaporizer or humidifier. Conversely, to decrease humidity, one can open windows when it is not humid outdoors or use an air conditioner with a humidity setting to make adjustments.
Understanding relative humidity is also critical when evaluating how it changes with temperature. Relative humidity is the ratio of vapor density to saturation vapor density. So, on a summer morning when the temperature is 20.0°C with a relative humidity of 90.0%, if the temperature later rises to 30.0°C and the water vapor density remains constant, the relative humidity will decrease. This is because warmer air can hold more water vapor than cooler air, effectively decreasing the relative humidity if the amount of water vapor stays the same.
To put it another way, the air contains a certain amount of water vapor, expressed as vapor density. The saturation vapor density increases with temperature. At the dew point, the relative humidity is 100%, and fog may form if the water droplets are small enough to stay in suspension.