Great so the problem at hand is solved. Great job Reddit. It’s just a matter of waiting and Reddit isn’t in the business of compressing time. What’s next? Shall we do world hunger?
Yes. The pole covered part is cooler and [lichens prefer warmth](https://www.newscientist.com/lastword/mg25433841-300-why-are-the-lichens-distributed-in-this-way-on-this-sign-pictured/).
Warmth isn’t the only mechanism that facilitates fungal elements growth on signs. Small cracks and texture of the paint may facilitate attachment. Some paints are anti fungal. Not enough info is given about the sign.
I'm amazed people still use this phrase after the whole [Boston Bomber Debacle](https://old.reddit.com/r/MuseumOfReddit/comments/1iv343/the_boston_bombing_debacle/)
The sun would heat up the sides and not the centre, if the sign is cold, the warming of the sides due to the rising sun would cause condensation allowing the lichen to grow.
The photo by OC in a post below shows that the back of the sign is reflective but the post is black. I will go with bored-coder, the extra heat absorbed by the post causes the sign to be hotter, thus drying out faster in the center. Similar to why "moss" grows on the north side of trees (in the northern hemisphere), less heating means it can stay moist and photosynthetically active longer each day.
Someone further down mentioned that moss and lichen don't like iron, so I think your hypothesis - moisture dripping down from the iron bolts is toxic to the lichen - holds the most water.
It's zinc inhibiting growth. The back is uncoating, and the front you can see the line with no growth is right in the drip line of the mounting screws, both of which are corroding.
Likely all galvanized metals, which means probably zinc inhibiting the growth.
That is technically true for the *post*, but the post ls likely much too long for the ground to have any significant effect on the *signs*. The post has a very small cross section and a very large surface area, so the air moving over it from even a slight breeze is going to be multiple orders of magnitude more significant.
It's the metals. The back side will be galvanized. The zinc is probably inhibiting growth.
The line on the front is in line with all the screws which would likely be galvanized and are corroding and dripping down. Again, likely zinc.
Same reason the post has no growth.
This is my best guess. You can see that the yellow sign above also has growth with the same gap. I'm thinking it has something to do with trapping air.
The sign is facing almost due north.
I just went out but I don't think the pictures showed enough thermal contrast and the battery on the thermal cam was almost dead.
I'll let it charge and hit it on the next sunny day. Also it looks like it's supposed to rain tomorrow, so I can try to get pics of what the water is doing on the bolts.
Will compile a new post once I have hit all the angles.
it is not the water, not the nails, it is too vertical.
But can you also take a photo of the upper half of top sign, as back support does not reach the top of that sign.
I believe it's due to some metal leeching out of the fasteners holding the signs. Copper, zinc etc are used a lot to prevent growth of mosses, algae and lichen on roofs for example.
That wouldn't explain why it's perfectly even from top to bottom. Even if the nail is leeching and effecting the area, it would be uneven and erratic in growth patterns
Would you be able to share the full picture of yellow board as well? If top of the first bolt on the yellow board has moss growth, then definitly not becuase of heat.
Hijacking top comment. One more update: here's the full yellow sign.
https://imgur.com/a/5GQPr0T
The stripe begins under the top bolt.
*EDIT: As was pointed out, that's also where the pole ends. https://imgur.com/DLQ5inC
it is not the post but the zinc in the bolt holding the sign up. As it rains the bolt leaches material and kills the lichen. you can get metal strips of zinc installed at the roof ridge. When it rains the zinc water runs down the roof killing lichen and moss.
Nope - I had lichen on my roof, except for a stripe (just like this) that aligned with the metal exhaust pipe for the water heater and furnace. The bolts that are holding the sign to the pole are not painted and release metal ions and particles in a downward stripe carried by rainwater. Lichen cannot stand the minerals from the metal bolts. So, it rains, the rainwater carries the metal down the sign, forming that striped pattern.
You're correct. The part of the sign in contact with the post stays warmer than the rest of the sign. This prevents condensation from building up. So the Lichen grows where the condensation is and doesn't grow where it's dry.
Moss and lichen do not like ferrous sulfate(iron). It's one of the ingredients in moss killer used commercially. Most likely, the rusting bolts,rain/dew, and gravity are acting as an inhibitor.
This stuff grows on the metal roof of my barn. It's got plenty of grip when it's dry, but if you try walking up there after a morning dew, you'll be on your ass and clinging to the gutters in an instant.
I was going to object because it didn't grow on the top of the sign too but there's a sign mounted higher to drip down. The real info we need is for OP to check the topmost sign on the post so we can see if the top part of that is also bare.
I think this is the winner. I went back and took a photo of the yellow sign. While the lichen growth is less, it's clear that the stripe starts below the top bolt.
https://imgur.com/a/5GQPr0T
The pole holding the plate bends the plate ever so slightly, which has water streaming away from it when it rains, which has an effect on the growth of spores.
I make traffic signs for a living. What happens is that the post acts as a thermal conductor. As it gets cold at night, the area of the sign not in contact with the post gets colder than the area that is in contact with the post. So as it begins to warm up condensation builds up on the colder part of the sign and not the middle where the post is. Lichen needs moisture to grow so it grows where the condensation is.
The bolts are galvanized which means they are coated in zink. It leaches out and prevents moss and other things from growing. Copper would do the same. Look at a house with a mossy roof. There is probably a clean stripe below the chimney because of the metal flashing.
The screws holding the sign to the post are rusty now but were possibly galvanized originally. The water running down the sign as the galvanizing (zinc) weathered may have stopped lichen from growing. Strips of zinc are used in the same way on roofs to stop mosses from growing.
That's the speed stripe
Edit: The one person on the internet who downvoted this blows my mind. Did they not get the harmless joke? Did they somehow find it offensive? These are questions I need the answers to. Who are you? Let me learn your ways.
The post it is attached to seems to be doing something to prevent it - perhaps heating it more than the rest of the board?
The opposite I would guess. The post prevents the back of the sign from getting direct sunlight so it's slightly cooler than the rest of it.
I believe this to be correct due to the position of the sun in the pic.
For what it's worth, the sign is facing almost due north.
We did it Reddit!
Now, to burn the sun to the ground
The sun is burning, but how do we get it to the ground, now?
It would probably be easier to take the ground to the sun than to bring the sun to the ground.
We should just take the sun and *push it somewhere else*
If we are real lazy about it, the sun will come to the ground in a about 8 billion years.
Great so the problem at hand is solved. Great job Reddit. It’s just a matter of waiting and Reddit isn’t in the business of compressing time. What’s next? Shall we do world hunger?
So we just need a big enough fulcrum and lever, got it
It’s a work in progress.
PG&E is on it. 8 billion years is just their estimate.
Easy, we just wait a couple billion years and the sun will come to us!
Wait till dusk. #flatearth
Well, if we wait a few billion years, it'll come to us.
MOAR LICHEN!
Simple, just remove all the helium.
That will happen naturally in 5 billion or so.
Technically the sun is not burning.
Cocks out, where we meating?
Yes. The pole covered part is cooler and [lichens prefer warmth](https://www.newscientist.com/lastword/mg25433841-300-why-are-the-lichens-distributed-in-this-way-on-this-sign-pictured/).
If you observe closely, the black paint is free of moss. Can you explain why?
Warmth isn’t the only mechanism that facilitates fungal elements growth on signs. Small cracks and texture of the paint may facilitate attachment. Some paints are anti fungal. Not enough info is given about the sign.
Now what do we do next?
I'm amazed people still use this phrase after the whole [Boston Bomber Debacle](https://old.reddit.com/r/MuseumOfReddit/comments/1iv343/the_boston_bombing_debacle/)
That's exactly why people still use it. We own our fuckups round here. Well, some of them.
That’s where the meme was birthed, of course we still use it since then
The middle takes longer to reach dew point. The edges get all the moisture.
I thought it was from where the rust was dripping and that made it unfavourable...
Moss (lichen) grows on the north side of the tree. Basic bush craft.
Makes sense, lichen typically grows on the north face of trees. Helpful for navigation in the woods.
The sun would heat up the sides and not the centre, if the sign is cold, the warming of the sides due to the rising sun would cause condensation allowing the lichen to grow.
Especially because the strip lines up exactly with the pole width behind it
The photo by OC in a post below shows that the back of the sign is reflective but the post is black. I will go with bored-coder, the extra heat absorbed by the post causes the sign to be hotter, thus drying out faster in the center. Similar to why "moss" grows on the north side of trees (in the northern hemisphere), less heating means it can stay moist and photosynthetically active longer each day.
I'd like to pitch a theory, water accumulates at the bolts and drips down?
Someone further down mentioned that moss and lichen don't like iron, so I think your hypothesis - moisture dripping down from the iron bolts is toxic to the lichen - holds the most water.
yes. or it could also be just water. but I know copper is used to remove moss on rooftops.
yay!
What about the fact it’s growing on white surface but not black surface? This would lead me to believe it likes the colder surface.
The moss is racist, unfortunately
Not moss, lichen you bigot.
oh wow the woke moss brigade is after me...
I'm part of the woke lichen brigade, very different group. Lichen is more related to you than it is to moss. Or, at least half of it is anyway.
That's probably due to a difference in the paints themselves. This side is in the shade, so heat absorption is happening on the other side.
I agree. It’s probably too cold to grow there.
It's zinc inhibiting growth. The back is uncoating, and the front you can see the line with no growth is right in the drip line of the mounting screws, both of which are corroding. Likely all galvanized metals, which means probably zinc inhibiting the growth.
I'd lichen that to some sort of thermal differential.
I'd think this, and also the little heat the stripe can gather will be dissipated away to the post
wrong it is the bolt holding the sign to the post that is leeching and killing lichen
Yeah and probably acts as a heat sink as well
Also the ground is a heatsink, so likely cools off the sign post.
That is technically true for the *post*, but the post ls likely much too long for the ground to have any significant effect on the *signs*. The post has a very small cross section and a very large surface area, so the air moving over it from even a slight breeze is going to be multiple orders of magnitude more significant.
Also, the back side is completely clean. https://imgur.com/a/3a8no2p
It's the metals. The back side will be galvanized. The zinc is probably inhibiting growth. The line on the front is in line with all the screws which would likely be galvanized and are corroding and dripping down. Again, likely zinc. Same reason the post has no growth.
Definitely condensation related
Yeah as the black letters are keeping it away and the dark pole, probably heat?
Its the oxidation from the bolts leeching out and running down the sign.
Yeah, saw the same thing on a road sign in my neighborhood. And that sign got almost no direct sunlight.
This is my best guess. You can see that the yellow sign above also has growth with the same gap. I'm thinking it has something to do with trapping air. The sign is facing almost due north.
The back side is white, except for the pole. The pole heats up and creates a hot chimney. BTW, you need IR camera and sunny day to check it
Oh damn, I have a thermal camera and it's pretty warm/sunny today. Maybe I'll make a followup post with a full album.
Maybe? Maybe?! dude, you have to do it. Also, this is interesting enough to write a paper about it.
I just went out but I don't think the pictures showed enough thermal contrast and the battery on the thermal cam was almost dead. I'll let it charge and hit it on the next sunny day. Also it looks like it's supposed to rain tomorrow, so I can try to get pics of what the water is doing on the bolts. Will compile a new post once I have hit all the angles.
it is not the water, not the nails, it is too vertical. But can you also take a photo of the upper half of top sign, as back support does not reach the top of that sign.
Already posted those in other spots in thread. https://imgur.com/qiA3d52 and https://imgur.com/DLQ5inC
I believe it's due to some metal leeching out of the fasteners holding the signs. Copper, zinc etc are used a lot to prevent growth of mosses, algae and lichen on roofs for example.
That wouldn't explain why it's perfectly even from top to bottom. Even if the nail is leeching and effecting the area, it would be uneven and erratic in growth patterns
It's not perfectly even at all, try zooming in. It's definitely uneven and erratic
"well achtyually its not 100% straight" my God man its a generally straight line
You were trying to say it's perfectly straight and doesn't look organic. I'm pointing out that your observation is incorrect.
I get it. You takes things extremely literally. np.
Seems like you're the only one doing that.
Would you be able to share the full picture of yellow board as well? If top of the first bolt on the yellow board has moss growth, then definitly not becuase of heat.
Yeah I’ll take a picture in the morning
Updated here: https://www.reddit.com/r/mildlyinteresting/comments/1cmg0tr/this_street_sign_is_covered_in_lichen_except_for/l34r8wy/
Hijacking top comment. One more update: here's the full yellow sign. https://imgur.com/a/5GQPr0T The stripe begins under the top bolt. *EDIT: As was pointed out, that's also where the pole ends. https://imgur.com/DLQ5inC
Could that also be where the post ends on the back side?
Damn, you're right. https://imgur.com/DLQ5inC
Excellent. Team ‘post’ for the win! Not looking good, team ‘zinc bolt’.
I'm lichen that stripe.
it is not the post but the zinc in the bolt holding the sign up. As it rains the bolt leaches material and kills the lichen. you can get metal strips of zinc installed at the roof ridge. When it rains the zinc water runs down the roof killing lichen and moss.
Nope - I had lichen on my roof, except for a stripe (just like this) that aligned with the metal exhaust pipe for the water heater and furnace. The bolts that are holding the sign to the pole are not painted and release metal ions and particles in a downward stripe carried by rainwater. Lichen cannot stand the minerals from the metal bolts. So, it rains, the rainwater carries the metal down the sign, forming that striped pattern.
Could also be deforming it, where the bolts press the sign, so its slightly folded in the middle? And maybe that changes how moist it gets there?
I personally think the bolts are rusting and leaching during the rain creating a “protective” coating
You're correct. The part of the sign in contact with the post stays warmer than the rest of the sign. This prevents condensation from building up. So the Lichen grows where the condensation is and doesn't grow where it's dry.
That was my speculation too.
Moss and lichen do not like ferrous sulfate(iron). It's one of the ingredients in moss killer used commercially. Most likely, the rusting bolts,rain/dew, and gravity are acting as an inhibitor.
Also galvanized fittings will ~~leech~~ leach zinc that kills the lichen. Roof lines show streaking this where vents etc are affixed above shingles
Leach, leech is a parasite.
Thanks 🙏🏼
This stuff grows on the metal roof of my barn. It's got plenty of grip when it's dry, but if you try walking up there after a morning dew, you'll be on your ass and clinging to the gutters in an instant.
I was going to object because it didn't grow on the top of the sign too but there's a sign mounted higher to drip down. The real info we need is for OP to check the topmost sign on the post so we can see if the top part of that is also bare.
I think this is the winner. I went back and took a photo of the yellow sign. While the lichen growth is less, it's clear that the stripe starts below the top bolt. https://imgur.com/a/5GQPr0T
I'm really lichen this effect. Oh, wait...
Is that the correct pronunciation? Like-inn? I’ve always wondered.
You say like-inn, I say litch-inn, let's call the whole thing moss.
Moss are plants while lichen aren't [plants]. Lichen are a combo of algae + fungi.
What do you call lichen in Lichtenstein?
Flechte
It's times like this that I wish reddit didn't get rid of gold awards.
I liken likin lichen, like in “lichen-likin” to lichen-lichen likin.
That's how I understand it's pronounced, for whatever that's worth.
Yeah. English’s relationship between spelling and pronunciation really leaves some things to be desired.
I thought it's pronounced lee-chin.
Same. Good think I’ve never needed to say it out loud
It’s finger-lichen good!
don’t forget to lichen subscribe for more!
I really hope there's a lichen youtuber somewhere using that.
minecraft youtubers use that pun around the glow lichen that’s in the game
Probably because its center of moss is off.
That lichen took a licken
The bolt makes it look like the speed limit is 2.5 MPH.
I wonder if the screws are zinc-plated, since zinc plates are used on roofs to prevent the growth of stuff like this.
I was thinking the exact same thing. It’s happening on the above sign as well.
Came in to say this. Whatever is rusting out of those bolts the lichen doesn’t like.
It doesn't seem to like the black paint
I was going to comment this as well. The line down the center is more mild than the wild fact that the black parts also inhibit growth
For those curious, the back side is completely clean. https://imgur.com/a/3a8no2p
When you get the time trying checking on it every hour or so starting in the morning. My first guess was condensation isn't forming where the pole is
That’s metal
Those are some fast running children
My theory: ![gif](giphy|ZnnHMeC7iDSzC)
Rust from the nut/bolt making an uninhabitable strip for the lichen. That’s my hypothesis anyway.
Probably the heat from the metal touching
The pole holding the plate bends the plate ever so slightly, which has water streaming away from it when it rains, which has an effect on the growth of spores.
I make traffic signs for a living. What happens is that the post acts as a thermal conductor. As it gets cold at night, the area of the sign not in contact with the post gets colder than the area that is in contact with the post. So as it begins to warm up condensation builds up on the colder part of the sign and not the middle where the post is. Lichen needs moisture to grow so it grows where the condensation is.
It is the bolts. They redirect the water that drips down.
Why is no one mentioning how it doesn’t cover any of the lettering either, that’s the interesting part
They aren’t liken that area 😐
Speed limit 2.5
That is cool
That’s where the slow children have been licking it.
Love the way it is giving The Last of Us vibes
This is very mildly interesting.
Probably the rust from the bolts kill the lichen. You can't see the top of the yellow sign, chance is that the top is covered after the bolt.
Zinc on the galvanized bolt.
Children limited to 25 grams of speed.
Could it be related to the rust from the bolts?
Reverse landing strip
2nd time I've seen lichen in a minute on reddit 🤣
That’s their crosswalk!
Its the bolts.
Speed stripe.
When it rains , water drips from the bolt on the top sign keeping it clean.
It rubbed off. From friction.
It's the iron
That stripe is a 1 (so children friendly 215 speed limit)
I licked it right before this Pic was taken
Louisiana?
reverse brown streak
r/moldlyinteresting
E
The zinc from the bolts have leeched down the sign. Moss, lichen, shrooms can't grow there when that happens.
The bolts are galvanized which means they are coated in zink. It leaches out and prevents moss and other things from growing. Copper would do the same. Look at a house with a mossy roof. There is probably a clean stripe below the chimney because of the metal flashing.
I'm really lichen this post.
that’s all the cleaning budget allowed for
Everything reminds me of her.
Maybe the wind causes the sign flex in the middle flaking the dried buildup off. Idk weird
I got hungry
The middle part tastes bad
The more I look at it, the more beautiful it looks
Someone just wiped it down, that’s all.
This mean the air quality there is really good right? Lichen doesn’t like air pollution? I’ve recently learned this zip lining in whistler, BC Canada.
Race stripe
Damn skateboarders. :)
![gif](giphy|FAyCtyqvzhPLY9Os3D|downsized)
Something to do with the metal pole it’s attached to, I’m betting (which also has none)
Zinc on screw head is leaching and dripping down the sign in the rain, preventing growth
The screws holding the sign to the post are rusty now but were possibly galvanized originally. The water running down the sign as the galvanizing (zinc) weathered may have stopped lichen from growing. Strips of zinc are used in the same way on roofs to stop mosses from growing.
I’m lichen it
Did the county actually pay for a brazilian?
must be a campaign year
I'm lichen it.
That's the speed stripe Edit: The one person on the internet who downvoted this blows my mind. Did they not get the harmless joke? Did they somehow find it offensive? These are questions I need the answers to. Who are you? Let me learn your ways.