Makin' Some Fog
Fog and clouds are similar. As a matter of fact, fog is just a cloud that happens to be on the ground. Understanding the process by which different fog types form will help us to better understand clouds.

Radiation Fog
Don't get scared, this is not dangerous radiation. This fog forms on cool clear nights when the wind is light or calm. During the night, heat from the ground continues to rise or radiate away from the earth. Without sunlight the temperature at the ground will continue to fall until it reaches the dew point or the sun comes up (there are other more complex possibilities). Remember, when the temperature and dew point are equal, clouds/fog begin to form.

Advection Fog
Advection is a fancy word for air moving due to wind. This type of fog can form when cold air moves over a warm body of water. The warmer humid air over the lake may be cooled to the dew point by the cold air mass as it moves in. Under extreme circumstances the interaction may cause precipitation.

Upslope Fog and Orographic Rain
This type of fog/cloud and rain/snow formation can be understood when you consider three facts:
 1. air will cool as it rises.
 2. when air is cooled to its dew point condensation will occur.
 3. air can't flow through a mountain so it goes over the top.
As wind blows toward a mountain, it will be forced upward. The air will cool on the way up and begin condensation when it cools to the dew point.