How does the relationship between temperature and dewpoint affect the likelihood of fog formation?

The correct answer highlights that a close temperature-dewpoint spread encourages fog formation. This is because fog typically forms when the air temperature drops close to the dew point. When the temperature and dew point are near each other, the air becomes saturated, meaning it cannot hold all the moisture as vapor. As a result, water vapor condenses into tiny droplets, creating fog.

The propensity for fog is especially pronounced during conditions of high humidity or when temperatures cool during the night, allowing the air to reach its dew point more easily. A very small difference between temperature and dew point indicates that the air is near saturation, which is ideal for fog to form.

The other options suggest conditions that do not favor fog development or misinterpret the relationship between temperature and dew point. Understanding this relationship is crucial for predicting fog and its impacts on visibility and weather conditions.