FAA Aircraft Dispatcher Practice Exam

What is indicated by a small temperature/dew point spread?

1. Increased visibility

2. Formation of fog is likely

3. Clear skies

4. Higher humidity levels

The correct answer is: Formation of fog is likely

A small temperature/dew point spread is indicative of an environment where the air temperature is very close to the dew point temperature. This condition suggests that the air is almost saturated with moisture, leading to high humidity levels. When the temperature and dew point are close together, the likelihood of condensation increases, which can facilitate the formation of fog, particularly during the cooler parts of the day when the temperature drops further. In contrast, increased visibility usually occurs when the air is drier, resulting in a larger temperature/dew point spread. Clear skies typically reflect drier conditions with stable air patterns, allowing for a larger spread between temperature and dew point. While higher humidity levels are a direct result of a small temperature/dew point spread, the most significant immediate implication of this scenario is the potential formation of fog. Thus, the correct answer focuses specifically on the forecast-related outcome of reduced visibility due to fog formation.