Why can you not see through fog when it’s ahead of you but you can once you’re in it?
In: Physics
You can see in fog when you’re in it?
Fog is opaique. This means that the deeper the fog the more of the light it blocks. So there are a lot of fog between you and an object you will not be able to see it. But when you come closer you are putting more of the fog behind you so there is less fog in front of you and you may start to see the object.
Let’s say you have big 1km x 1km sheets of fog. Seeing through one or maybe two won’t be perceptibly different than seeing through normal air. If you continue to stack them, you still see through the first few but it’ll get gradually harder until light is effectively blocked from letting you see clearly.
So being inside the fog cloud is like being surrounded by these sheets (more like shells, instead). You see through the first few, but with more fog, you see less. This all of course depends on fog density, too, but the gist is there.
You have a bunch of particles in the fog blocking your vision. Let’s say there are particles directly in front of you blocking ten percent of your field of view and they’re evenly distributed as small bits in the air. And then another. And five feet away, there’s some more particles blocking another ten percent of your vision. That’s twenty percent. The farther away you go, the more particles are there getting in between you and what you want to see.
It’s like your window blinds. If you crack them open *just a little bit*, you can see through them a little bit. If you get real close to them, you can see a LOT through them (because you are closer to the spaces between them). But if you walk back 100 feet from them, you can’t see through them at all, because you are too far away from the spaces.
Edit: now add a few more blinds in front of the one you are looking through. More blinds, less chance to see through them all.
Assuming you mean while driving. It’s because the fog is reflecting light from your headlights back at you, and that light is brighter than the actual landscape/road. So all you see a wall of white reflected light.
Behind you there are no headlights, so the brightest source of light is the dimly lit landscape/road.
This is why fog lights are mounted higher or lower than the normal headlights. The light reflected back from the fog is not as direct.
You’re seeing through the fog the same amount either way. When you’re outside the fog, you’re seeing maybe 5 feet into it, but since you’re further away, it’s hard to tell how much of the fog you’re seeing through. When you’re inside it, you can tell more clearly that it’s about 5 feet.
Same reason you can easily see your friends who are with you in the crowd, but you’ll never see them in the distance amongst a crowd of 100,000
You can only see a certain distance into the crowd/dog, where you are.
Density.
Fog is a visible aerosol consisting of tiny water droplets suspended in the air. When viewed from a distance you see the layers.
Picture a net. Put it close to your eyes and you can see through the holes as if it isn’t there. Put it really far away and it looks like it doesn’t have any holes at all.
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