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Why I feel cool in a region with lot of trees inspite of humidity by transporation?

Today I went for a walk and entered a region with lot of trees, It feel a sudden chill, a cool feeling (comparatively) Why, Although trees perform transpiration that cause moisture so we should feel warm but I feel cool?

So i search for answer, i got to know that tree absorb heat from surrounding to change liquid water into water vapor through transpiration. But it create a query. Although environment is cool still! There are lot of moisture too!! Due to transpiration. So how could i feel cool although atmosphere cannt contain much sweat that cause cooling, so according to this i should feel hot, still i feel cool! But how? If sweat cannt evaporate althogh environment is cool?

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  • $\begingroup$ @user15032172 Undelete your thread, and I’ll tell you how to solve your problem. $\endgroup$ Oct 16, 2021 at 19:41

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Why, Although trees perform transpiration that cause moisture so we should feel warm but I feel cool?

This is actually a very good question. There appears to be two competing factors involved. Evaporative cooling due to transpiration from the trees cools the air, increasing heat transfer away from the skin making it feel "cooler". But at the same time you would think transpiration increases the humidity in the air, potentially interfering with evaporative cooling of skin perspiration, making you feel "warmer"

The fact that you experienced "cool" rather than "warm" suggests to me that the relative humidity (RH) of the air was low at the time, so that it was capable of absorbing the moisture and cooling the air without significantly raising the RH under the tree to interfere with evaporation of skin perspiration, thus making you feel "cool".

If the RH was high, particularly at or near saturation (100%), transpiration evaporation from the tree, and its cooling effect, ceases. Likewise, evaporative cooling of perspiration ceases, both of which would make you feel "warm". For more information on transpiration of plant, see: https://www.polygongroup.com/en-US/blog/how-humidity-affects-the-growth-of-plants/

Bottom line: The higher the RH the warmer you will feel, whether you are under a tree or not.

Hope this helps.

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  • $\begingroup$ it was capable of absorbing the moisture and cooling the air without significantly raising the RH under the tree to interfere with evaporation of skin perspiration, thus making you feel "cool". Why it does raise RH under tree? Is that only for that time, because transpiration continue and one time will come when transpiration stops due to high RH? Isnt it? Is that any other thing making us feel ' extraordinary ' cooling (sudden chill) does body radiate more heat in that cool environment? Making us feel too cool high radiation + evaporation $\endgroup$
    – user315475
    Oct 17, 2021 at 4:50
  • $\begingroup$ Unless we are talking about a forrest of trees, the air under a single tree is not isolated from the surrounding air into which the water vapor created under the tree can disperse. And if the humidity outside the tree is low it makes it unlikely that transpiration due to the tree will raise the local (under the tree) humidity enough to cause evaporation to cease. All of this assumes the humidity all around is not already high, i.e., close to saturation, as I said in my answer. $\endgroup$
    – Bob D
    Oct 17, 2021 at 16:01
  • $\begingroup$ But what is the main special reason behind a sudden chill!! I mean if that amount of humidity present in hot atmosphere, than our evaporation rate will be same as in Forest still we will feel hot. But here same amount of humidity in forest cool area make us feel a chill!! Is that in cold temperature heat radiation rate from our body increase?? Because some wind feel cooler than other wind, why dies heat radiation rate from bidy increased in cool atmosphere? So that in 2 environment with same amt of water vapor only difference is one environment is cool seconf is warm $\endgroup$
    – user315475
    Oct 18, 2021 at 6:51
  • $\begingroup$ We will feel cool in 1st environment with cool+ same amount of water vapor as 2nd? As u said "Evaporative cooling due to transpiration from the trees cools the air, increasing heat transfer away from the skin making it feel "cooler" in ur answer, does heat tranfer rate increase(in unit tine)?? Or overall heat tranfer increase(at same rate but more heat tranfer in cool)?? $\endgroup$
    – user315475
    Oct 18, 2021 at 6:52
  • $\begingroup$ You are getting into an area (physiology) where I don’t have expertise. Sorry. $\endgroup$
    – Bob D
    Oct 18, 2021 at 7:23
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The feeling of being cool can happen through two reasons

  1. You are cooling off via sweating/evaporation
  2. The environment is actually just cold, independent of how you cool yourself off.

The reason you feel cool around trees DESPITE increased humidity is (2). The trees have actually cooled the environment around them via transpirative cooling. So regardless if the humidity of the environment is higher you still feel cool around the trees.

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    $\begingroup$ "So regardless if the humidity of the environment is higher you still feel cool around the trees" Actually, that is not correct. If the relative humidity is too high, evaporation due to transpiration of the trees, along with its cooling effect, ceases. The only cooling effect is that of the tree shade from thermal radiation. See: polygongroup.com/en-US/blog/… $\endgroup$
    – Bob D
    Oct 17, 2021 at 2:14
  • $\begingroup$ I agree if humidity is too high transpirative cooling doens't work and I also agree that that shade definitely helps cool things, but are you claiming that transpiration does not result in ANY noticeable cooling? I've definitely read a few articles here and there that claim otherwise (of course I shouldn't believe everything i read on the internet) $\endgroup$ Oct 17, 2021 at 16:59
  • $\begingroup$ Here was like link #1 on google which claims the same (again, its entirely possible it is wrong/i am wrong for believing): trees-energy-conservation.extension.org/…. $\endgroup$ Oct 17, 2021 at 17:00
  • $\begingroup$ I didn't say there would be no evaporative cooling, but the rate of cooling diminishes with increasing humidity and ultimately stops when the air is saturated, just like any other evaporative cooling. I see nothing in you link that talks about the effect of humidity. My link does. $\endgroup$
    – Bob D
    Oct 17, 2021 at 17:20
  • $\begingroup$ Oh I see, i misunderstood your comment. So that means my answer ceases to hold true as humidity approaches saturation point $\endgroup$ Oct 17, 2021 at 17:22