Sea smoke has formed over the fjord in the current cold spell. Locally, thanks to the warming affect of the fjord it didn’t go much below -15C in the night. It’s significantly colder on the other side of the fjord where it was about -20C this morning, cold air (below -30C currently inland) sinking along the major river valley (Stjørdalselven) into the fjord basin.
Sea smoke  forms when a light wind of very cold air mixes with a shallow layer of saturated warm air immediately above the warmer water. The warmer air is cooled beyond the dew point and can no longer hold as much water vapor, so the excess condenses out. The effect is similar to the “steam” produced over a hot bath or a hot drink, or even an exercising person (Wikipedia).
Thus, it’s confined to the water and we almost never have fog on land here. The smoke tends to form thickest on the other side of the fjord where it’s coldest.
The sea smoke was constantly changing this morning, witness these pictures and the video where the low lying smoke drifts quickly from land to fjord, whereas the waves that can be seen are coming from a different direction, probably driven by the sinking air (wind) coming out of the river valley in a different direction.

11th February: Still cold at -15C this morning (¨20C on the other side of the fjord and down to -40C inland). Two new videos added below (at the top):