<p>Sometimes, people say things like &quot;It's only <span class="math-container">$5^\circ\mathrm{C}$</span> outside, but there is a warm wind, and it feels much warmer&quot; (I live in Austria, a region where there are <em>Föhn</em> winds). I have a hard time agreeing to such statements, and I think they might not be correct. In the following, assume a cloudy day, so that we may ignore the effect of the sun, which is hard to quantify. Relevant aspects I am aware of are:</p>
<ul>
<li>First of all, the air has a measurable temperature (the <span class="math-container">$5^\circ\mathrm{C}$</span>). That one is unique (i.e. there is no second, &quot;intrinsic&quot; temperature that appears in the warm wind).</li>
<li>There is the concept of &quot;<a href="https://en.wikipedia.org/wiki/Apparent_temperature" rel="nofollow noreferrer">apparent temperature</a>&quot;, which factors in humidity and wind chill. Generally, this is used to explain why the &quot;feels-like&quot; temperature is <em>lower</em> than the one measured by the thermometer.</li>
</ul>
<p><strong>Question</strong>: Are there other factors that I am missing that might make the wind appear &quot;warmer&quot; (than the temperature shown on the thermometer)? Something that would justify a statement like this: &quot;The thermometer shows <span class="math-container">$5^\circ\mathrm{C}$</span>, but it <em>feels</em> like <span class="math-container">$10^\circ\mathrm{C}$</span>&quot;.</p>
<p><strong>Explanation attempt</strong>: Consider a couple of days, all with a measured temperature of <span class="math-container">$5^\circ\mathrm{C}$</span>, and for most days, the humidity is at <span class="math-container">$50\%$</span>, except for one day, where it is at <span class="math-container">$80\%$</span>. Then the latter day would appear warmer than the other days:</p>
<ul>
<li>On low-humidity days, the apparent (&quot;feels like&quot;) temperature would be lower than <span class="math-container">$5^\circ\mathrm{C}$</span>.</li>
<li>On the high-humidity day, the apparent temperature would be close to the actual <span class="math-container">$5^\circ\mathrm{C}$</span>.</li>
</ul>
<p>In comparison, the high-humidity day will feel warm. It's not so much that it feels warmer than <span class="math-container">$5^\circ\mathrm{C}$</span>, but that the low-humidity days feel cooler than <span class="math-container">$5^\circ\mathrm{C}$</span>. But I am not sure if this argument actually holds up, since the effect of humidity on humans is mostly due to perspiration, and it is much greater for higher temperatures.</p>
<p><strong>Follow-up question</strong>: Would you agree with this, or are there other explanations?</p>

CC BY-SA 4.0
2023-11-15T08:38:56.433Z
If föhn increases the temperature, then thermometres will reflect that.
gerrit
CC BY-SA 4.0
2023-11-15T08:50:09.167Z
Right - I have clarified this a bit better in my question.
DominikS
CC BY-SA 4.0
2023-11-15T10:20:30.587Z
Interesting question.  I wonder if this could happen in an inversion situation, but then it would be due to radiation, not wind. It's well-established that indoors, the "felt temperature" depends both on room air temperature and on wall temperature [example source](https://rldecor.com/confort-thermique/?lang=en). By analogy, -10°C with a clear sky and no inversion should feel colder than -10°C with a 0°C low cloud layer for the same wind and humidity.  But föhn is dry and near the surface so should not be compatible with an inversion situation....
gerrit
CC BY-SA 4.0
2023-11-16T06:49:00.600Z
I have a spreadsheet that does these sorts or calculations. I entered some numbers to see what would be needed for your situation to occur. For a dry bulb temp of 5 &degC & a Steadman apparent temp of 10 &degC, with a wind speed of 10 km/h wind a wet bulb temp of 20 &degC would be required which would give a relative humidity of 375%. I don't see how this would be be possible.
Fred
CC BY-SA 4.0
2023-11-16T09:23:32.757Z
Yes, this seems out of the applicable range of the formulas. :)
DominikS
<temperature><humidity>
Is there such a thing as a "warm wind"?
DominikS
# Is there such a thing as a "warm wind"?

(Asked by: username_0 on 2023-11-15)

Sometimes, people say things like "It's only $5^\circ\mathrm{C}$ outside, but there is a warm wind, and it feels much warmer" (I live in Austria, a region where there are *Föhn* winds). I have a hard time agreeing to such statements, and I think they might not be correct. In the following, assume a cloudy day, so that we may ignore the effect of the sun, which is hard to quantify. Relevant aspects I am aware of are:

* First of all, the air has a measurable temperature (the $5^\circ\mathrm{C}$). That one is unique (i.e. there is no second, "intrinsic" temperature that appears in the warm wind).
* There is the concept of "[apparent temperature](https://en.wikipedia.org/wiki/Apparent_temperature)", which factors in humidity and wind chill. Generally, this is used to explain why the "feels-like" temperature is *lower* than the one measured by the thermometer.

**Question**: Are there other factors that I am missing that might make the wind appear "warmer" (than the temperature shown on the thermometer)? Something that would justify a statement like this: "The thermometer shows $5^\circ\mathrm{C}$, but it *feels* like $10^\circ\mathrm{C}$".

**Explanation attempt**: Consider a couple of days, all with a measured temperature of $5^\circ\mathrm{C}$, and for most days, the humidity is at $50\%$, except for one day, where it is at $80\%$. Then the latter day would appear warmer than the other days:

* On low-humidity days, the apparent ("feels like") temperature would be lower than $5^\circ\mathrm{C}$.
* On the high-humidity day, the apparent temperature would be close to the actual $5^\circ\mathrm{C}$.

In comparison, the high-humidity day will feel warm. It's not so much that it feels warmer than $5^\circ\mathrm{C}$, but that the low-humidity days feel cooler than $5^\circ\mathrm{C}$. But I am not sure if this argument actually holds up, since the effect of humidity on humans is mostly due to perspiration, and it is much greater for higher temperatures.

**Follow-up question**: Would you agree with this, or are there other explanations?

**Tags:** temperature, humidity

> **Comments:**
> **username_1**: If föhn increases the temperature, then thermometres will reflect that.  
> **username_0**: Right - I have clarified this a bit better in my question.  
> **username_1**: Interesting question.  I wonder if this could happen in an inversion situation, but then it would be due to radiation, not wind. It's well-established that indoors, the "felt temperature" depends both on room air temperature and on wall temperature [example source](https://rldecor.com/confort-thermique/?lang=en). By analogy, -10°C with a clear sky and no inversion should feel colder than -10°C with a 0°C low cloud layer for the same wind and humidity.  But föhn is dry and near the surface so should not be compatible with an inversion situation....  
> **username_2**: I have a spreadsheet that does these sorts or calculations. I entered some numbers to see what would be needed for your situation to occur. For a dry bulb temp of 5 &degC & a Steadman apparent temp of 10 &degC, with a wind speed of 10 km/h wind a wet bulb temp of 20 &degC would be required which would give a relative humidity of 375%. I don't see how this would be be possible.  
> **username_0**: Yes, this seems out of the applicable range of the formulas. :)  

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## 0 answers

