Final answer:
50 percent humidity means the air contains half of the maximum moisture it could hold at that temperature; it's a measure of relative humidity, not a predictor of temperature, precipitation chances, or thunderstorms.
Step-by-step explanation:
When we talk about 50 percent humidity, we are referring to the relative humidity of the air. Relative humidity is a measure of how much water vapor is present in the air compared to the maximum amount it could contain at that temperature. When the relative humidity is 50%, it means the air contains 50% of the moisture it can hold before it becomes saturated and cannot hold any more moisture. At this point, no additional water vapor can be added without some water condensing into liquid. This measure does not directly indicate the temperature, the chance of precipitation, or the probability of a thunderstorm.
Relative humidity varies with temperature; as the temperature decreases, the relative humidity increases, potentially reaching 100%, which is known as the dew point. At the dew point, the air is fully saturated, and any additional cooling will result in condensation, forming dew or fog. For drying purposes, hot air is more effective than cold air because it can hold more water vapor, facilitating evaporation.