Why can you not see through fog when it’s ahead of you but you can once you’re in it?
In: Physics
When your driving, before you hit the fog 100% of your light is being reflected back (not actually but for the sake of the argument). Once your in the fog, the light gets scattered and absorbed as it goes through, so an object further in the fog will reflect less light including the fog itself.
When you’re in a forest, you can’t see out of the forest, but you can look between trees nearby. Fog is like that, but instead of trees, you have little pieces of water that look white floating through the air. The further your are away from something the more water is between you two, so it gets harder to see. This is the game reason why it’s harder to see trees farther away in the forest.
Just picture it as a bunch of mesh screens that are spaced apart. You may be able to see through a few layers but eventually all the lines will over lap and you won’t be able to see past a certain screen
Why can you see the bottom of a kiddie pool but you can’t see the ocean floor?
Why can you see through one pair of sunglasses but if you put 10 together it’s just all dark?
Why does something that obsures you vision a little when there’s a little of it obscure your vision more when there’s more of it???
You can see through fog from the outside. It’s just that being outside of the patch of fog you can see only the fog behind it. If it’s thick enough you’d likely not see to the end of the patch of fog from inside either.
There’s lots of tiny droplets that from far away appear as a single mass. Like you can see say 10 feet in front of you if you’re in the fog. From outside you can see less based on how far away you are from the particles kinda like the opposite of a raster image
You know how in Fog you can see e.g. 20 meters before it’s all gone?
Those same 20 meters are much smaller when you’re far away.
TLDR: Cows: Small or Far Away?
Ahead of you, you have the entire fog blocking your view. When you are in it, you have less of it blocking your view.
On that note, why can cameras see through the fog that YOU can’t???
It’s a bit of a perception illusion.
As the top commenter pointed out, sometimes you can see through it (if it’s a small patch of fog) because once you are in the fog, there is less ‘density’ of fog between you and the objects on the other side of the fog.
But I think your real question is, why does it seem that you can’t see anything that’s IN the fog, but once you’re in the fog, you can see some things that are out of the fog.
This is where the illusion comes in.
When you are outside of the fog, looking into it, it seems like you can’t see anything in there because perceptually your wider vision is clear and this one area is obscured. You actually CAN see pretty far into the fog (equally as far as you can see out of it) but you eyes and brain are adjusted to the light level and clear landscape around you. Once you are inside the fog, you adjust to the low-contrast environment and it becomes easier to pick out faint objects that are outside of the fog (as the top commenter said, this is also aided by the fact that there is less ‘density’ of fog between you and an outside object in this case).
Another thing contributes to this perceptual illusion. Often when we encounter fog we are driving. If there is a patch of fog ahead that you are driving into, it can appear totally opaque party because there is only open road in front of you, IE there are no tall, distinct objects in the road that you would otherwise be able to faintly make out. Once you are IN that patch of fog, the trees / houses / ETC on the side of the road are visible because they are distinct objects, giving the slight illusion that you just drove into an opaque area but can somehow now see things in that area. In other words, it wasn’t as opaque as you though, it’s just that there wasn’t very much directly ahead of you TO SEE (except open road or faded pavement, which don’t stand out in contrast through the fog.
A (freaky) example of this is if you’ve ever had the misfortune to encounter a deer in the road in a patch of fog (I’m looking at you, Vermont State highways). It looks like a patch of dense fog with a deer just floating in the middle of it. In reality, the deer is standing on the road, but the faded pavement and striping can’t be made out in the fog and neither can the clear road / sky beyond. What you realize in this case is that you actually CAN see pretty far into the fog, it’s just that there isn’t always much TO SEE.
This is a psycho-physiological effect.
When the fog is in front of you, your eyes and brain are adjusted notice the clear features of the unfoggy landscape around you. The fainter details inside the fog are:
1. further away than the clear landscape and cover only a small part of your visual field
2. harder to perceive than the clear landscape
3. subject to bigger contrast in lighting and luminance conditions
Once you are inside the fog:
1. There are no more distinct features to distract you
2. Your eyes have adjusted to the difference in light scattering and luminance
3. The foggy part of the landscape is now your entire visual field
So both your eyes and your brain adjust to make you perceive more details about things in the fog.
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