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I am a writer, and this question is for a fictional work. However, given its nature, I believe it is better suited here than Writers Stack Exchange.

In my fictional world, I have an area that is supposedly covered with fairly thick fog during most of the night and nearly all of the morning (it can leave a bit before noon if necessary). My question is this: What factors would I need to achieve this effect?

Factors: It is a fantasy world, so the factors need to be natural. The area is within a city, and is very densely inhabited. The area is enclosed by large trees, and large roots run all over the ground. The fog does not need to reach any higher than 7 feet, but it does need to cover nearly the whole area (a generous approximation would be 288 ft by 228 ft - about 65,000 square feet). The walls of the area (giant roots/tree trunks) vary in distance from each other a lot.

Let me know if you need more details on the surroundings.


closed as off-topic by milancurcic, Isopycnal Oscillation, Pont, arkaia, casey Jan 21 '15 at 3:26

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about earth science, within the scope defined in the help center." – milancurcic, casey
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ I think to fully answer - it would be very interesting to know more about the local topography (valley, mountain, field, peninsula?) Also what about the presence of a water body (seashore, lake, river)? I am asking because those are some factors which may be important regarding the formation of a fog, IMO. $\endgroup$ – Etienne Godin Jan 20 '15 at 20:48
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    $\begingroup$ Off-topic. Belongs on worldbuilding.stackexchange.com. $\endgroup$ – milancurcic Jan 20 '15 at 21:01
  • $\begingroup$ The easiest thing would be to put the city in an elevated area (e.g. on the side of a volcanic mountain) such that ground level is regularly exposed to clouds passing by. $\endgroup$ – farrenthorpe Jan 20 '15 at 21:16
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    $\begingroup$ Although the context for the question is a fictional world, it is still relevant to the natural world. The city could also be in a low-lying area where the valley 'fills' with fog and I believe that would be more conducive to regular persistent fog than on the side of a mountain. Conceivably could be subject to coastal fog like San Francisco. $\endgroup$ – haresfur Jan 21 '15 at 2:05
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    $\begingroup$ @TommyMyron: You could edit this question to be on-topic on this site, and keep the WorldBuilding.SE question as is. Something along the lines of "Are there any parts of the world that regularly have fog until late morning, and if so, what factors cause that phenomenon?" or just "What causes late-morning fogs?" would be pretty on-topic, and would complement this question on WB.SE. $\endgroup$ – naught101 Jan 22 '15 at 3:13

The heat of the Sun can "burn off" fog. So a lack of direct sunshine, cool temperatures & humidity (evaporation of water from a nearby body of water or saturated or wet ground) are key to maintaining fog. The air must be moist!


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