# Fog, water droplets, and how pine trees collect the water **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2016, 3:59pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539 "2016-03-19T15:59:10Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![All\_About\_M3](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@All\_About\_M3](https://boards.straightdope.com/u/All_About_M3)\ **Post date:** [March 19, 2016, 3:59pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/1 "2016-03-19T15:59:10Z")
I know (or at least I think I know) that pine trees use their needles to collect water. However, I do not know quite how they do this. Do the needles/trees just wait for the fog to condense, or do they have a way to speed up/cause the fog to condense? Also, does the fog even need to be condensed, because the [fog wiki](https://en.wikipedia.org/wiki/Fog) says fog “It is a visible mass consisting of cloud water droplets or ice crystals suspended in the air at or near the Earth’s surface.” I am confused about the fact that fog “[consists] of cloud water droplets”. If the fog is made of water droplets, and not water vapor, then there is no need for condensation to collect water, since it is already tiny droplets? Unless _cloud_ water droplets are different from water droplets? But if fog is made up of tiny water droplets, why don’t people get wet when walking through fog, like when walking through a drizzle? Perhaps it just happens on a smaller, much less noticeable level? I guess, now that I think about it, droplets form everywhere when in fog, but I always thought this was from condensation, not from the fog being made of water particles. Sorry, I know I have a lot of questions in here, but I didn’t think it was worth separate threads. To clarify what I’m asking: [ul] [li]How to pine trees get water from fog. Specifically, I am wondering condensation is needed.[/li][li]If fog is made of cloud water droplets, why don’t people get wet when walking through fog?[/li][li] Is the water that appears on objects in fog from condensation, or from the fog being made of cloud water droplets?[/li][/ul] Thank you very much. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [March 19, 2016, 4:12pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/2 "2016-03-19T16:12:57Z")
Its not condensation in the sense of water vapour undergoing the phase change to liquid, but in the sense smaller droplets consolidating into larger droplets. ---
**Author:** ![All\_About\_M3](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@All\_About\_M3](https://boards.straightdope.com/u/All_About_M3)\ **Post date:** [March 19, 2016, 4:55pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/3 "2016-03-19T16:55:35Z")
Okay, that’s what I was looking for. Thanks. Do you know of a book or online resource where I can read about how this occurs (how the small droplets consolidate into big droplets)? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 19, 2016, 5:04pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/4 "2016-03-19T17:04:41Z")
> [@All\_About\_M3](#): > > If fog is made of cloud water droplets, why don’t people get wet when walking through fog? They do. Well, they get damp. Fog isn’t very dense. If you go out into a foggy night with a very bright light, you can see the individual droplets swirling in the air. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [March 19, 2016, 7:00pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/5 "2016-03-19T19:00:12Z")
I haven’t read any mention anywhere that pine trees get water from fog through their needles, although now that you mention it, it sounds plausible. I’ve certainly read many many times that redwood trees do this. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [March 19, 2016, 10:14pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/6 "2016-03-19T22:14:01Z")
“Fog” is simply a wisp of a “Cloud” which happens to be at ground level. More or less. Drizzle is a super-saturated cloud. ---
**Author:** ![Richox](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@Richox](https://boards.straightdope.com/u/Richox)\ **Post date:** [March 20, 2016, 2:08am UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/7 "2016-03-20T02:08:42Z")
I thought pine tree needles were an adaption to prevent damage from frost and snow, not to help collect water. If you are in a climate where fog exists and therefore likely plenty of precipitation, why can’t you take groundwater like most other trees? The negative affect of pine needles would be reduced area for photosynthesis as well, right? ---
**Author:** ![bb49](https://avatars.discourse-cdn.com/v4/letter/b/b38774/32.png) [@bb49](https://boards.straightdope.com/u/bb49)\ **Post date:** [March 20, 2016, 2:10am UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/8 "2016-03-20T02:10:04Z")
I’m not sure exactly how true this is. Most pine trees grow in dry climates, and very little fog. And they don’t usually grow very large. But as one person mentioned, redwoods grow pretty damn big, in a climate that has very little rainfall, but they draw the required moisture from fog. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [March 20, 2016, 3:34am UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/9 "2016-03-20T03:34:03Z")
Don’t trees also lower the temperature around themselves? I seem to remember learning this in my old Botany class: forests are cooler than surrounding areas, and not solely because of the shade, but because of trees micro-exhalation of (???) water vapor. Could this temperature difference be part of the collection and condensation of water from the air? (I was in a wilderness park area, where the rangers had done some re-planting of native bush and shrub, and they’d put a small round cobblestone right by each of the plantings. Is that also to help condense moisture and “water the plants?” Or is it to collect the day’s warmth from sunshine, to combat freezing on coldest nights?) ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [March 20, 2016, 4:09am UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/10 "2016-03-20T04:09:52Z")
> [@Richox](#): > > I thought pine tree needles were an adaption to prevent damage from frost and snow, not to help collect water. If you are in a climate where fog exists and therefore likely plenty of precipitation, why can’t you take groundwater like most other trees? Plants suck up groundwater through the roots and up into the above-ground parts of the plant by a combination of several mechanisms, mainly capillary action. I had always learned that capillary action can only lift water to a certain maximum height, but redwoods (and some pines, like the Ponderosa pine) are way too tall for that. So that’s why they need to absorb fog through the leaves to get water to the higher parts of the trees. I’ve seen that explanation given many times and places. BUT WAIT – I’ve just been googling that to fill in some of the details (like just how high capillary action can get the water, or at least a cite for the above claims) – and I’m not finding it. Instead, I just skimmed through several articles that describe all the mechanisms trees have for getting water from the ground all the way up to the top, and I didn’t notice anything about there being a height limit. Instead, there are discussions of all the ingenious mechanisms that have evolved to make it work. Example: [How do large trees, such as redwoods, get water from their roots to the leaves?](http://www.scientificamerican.com/article/how-do-large-trees-such-a/), from Scientific American. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [March 20, 2016, 4:18am UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/11 "2016-03-20T04:18:54Z")
The above-cited page from Scientific American does mention a limit for capillary action in drawing up the water: > [@](#): > > Capillary action and root pressure can support a column of water some two to three meters high, but taller trees–all trees, in fact, at maturity–obviously require more force. In some older specimens–including some species such as _Sequoia, Pseudotsuga menziesii_ and many species in tropical rain forests–the canopy is 100 meters or more above the ground! The various other mechanisms and forces are discussed. ---
**Author:** ![All\_About\_M3](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@All\_About\_M3](https://boards.straightdope.com/u/All_About_M3)\ **Post date:** [March 23, 2016, 8:18pm UTC](https://boards.straightdope.com/t/fog-water-droplets-and-how-pine-trees-collect-the-water/749539/12 "2016-03-23T20:18:31Z")
> [@Senegoid](#): > > The above-cited page from Scientific American does mention a limit for capillary action in drawing up the water: > > The various other mechanisms and forces are discussed. I had in mind when asking these questions the [Torrey pine](https://en.wikipedia.org/wiki/Torrey_pine), which that linked Wikipedia article states are 8-17 meters tall. While no redwood, 8 meters is definitely about the 2-3 meters that article says can support capillary action. Thanks.