A small temperature/dewpoint spread typically results in:

A small temperature/dewpoint spread indicates that the air is close to saturation, meaning excess moisture is present in the atmosphere. When the temperature and dewpoint are near each other, it often leads to the formation of fog and low clouds. This occurs because as the temperature drops at night or in humid conditions, the air can become saturated, leading to condensation and the development of fog.

In contrast, a larger temperature/dewpoint spread generally signifies drier air, which tends to result in clearer skies and better visibility. Thunderstorms typically develop with significant instability and a more considerable temperature difference, while high turbulence is commonly associated with stronger temperature gradients and wind shear, which are not present under conditions of small temperature/dewpoint spread. Therefore, the conditions associated with a small temperature/dewpoint spread are most closely linked to the formation of fog and low clouds.