What's the connection between the dew point and fog?
Let's begin by defining 'the dew point'. It's simply the temperature at which the atmosphere will become saturated with water...in the form of a gas. We call it 'water vapor'. There's no 'magic' dew point at which fog will form. It's when the air temperature cools to the dew point that fog will form. The closer the dew point and the air temperature, the more likely it is that fog will form. That cooling trend is most likely when winds are light.