Final answer:
Humidity levels significantly influence the intensity and duration of rainfall. Higher humidity tends to result in higher rainfall rates and longer durations of rainfall.
Step-by-step explanation:
The meteorological factor that significantly influences the intensity and duration of rainfall is humidity levels. Warm air can hold more moisture than cold air, so areas with higher humidity tend to have higher rainfall rates and longer durations of rainfall. Additionally, changes in humidity can affect evaporation rates, which can in turn impact precipitation. For example, increasing humidity can lead to reduced evaporation rates due to increased difference in water vapor pressure between the leaf and atmosphere.