Final answer:
The relative humidity is likely to increase when the sun goes down and the temperature drops, as cold air can hold less water vapor than warm air, and the amount of water vapor remains constant.
Step-by-step explanation:
If the relative humidity (RH) is 44% and the sun goes down, the RH is likely to increase. Relative humidity is the amount of water vapor present in the air expressed as a percentage of the amount needed for saturation at the same temperature. As the temperature drops, the air can hold less moisture, and since cold air can hold less water vapor than warm air, the relative humidity increases if the amount of water vapor stays constant. This is why cool evenings often have higher relative humidity levels than warmer days, assuming the water vapor density remains the same.
An example to illustrate this concept is: Late on an autumn day, the relative humidity is 45.0% at 20.0°C. If the temperature drops to 10.0°C in the evening and we assume a constant water vapor density, the relative humidity will increase. This is because the saturation point of water vapor in the air at 10.0°C is lower than at 20.0°C, so the same amount of water vapor constitutes a higher percentage of the air's new saturation point at the cooler temperature, leading to an increase in RH.