<p>The glass will be receiving heat from the inside and transferring it outside via several mechanisms, both radiant heat in the infrared and conduction/convection by its contact with the warm indoor air and cold outdoor air.</p>
<p>It's difficult to say for sure which loss mechanism is most important in this case, but <a href="https://earthscience.stackexchange.com/a/19940/6031">the other answer</a> only mentions radiation and as suggested in comments there it's hard to believe that the reduced motion of the air around the branch isn't contributing significantly.</p>
<p>It's also important to point out that lateral heat flow within the glass from the warmer to the colder areas of the glass is also important. If the window were made of the fictitious &quot;transparent aluminum&quot; with high thermal conductivity, it would be a uniform temperature. It's only because the conductivity of the glass is so low that it can support a thermal gradient.</p>

CC BY-SA 4.0
2020-07-19T06:30:23.430Z
2020-07-19T06:30:23.430Z
uhoh
<p>The branch block outgoing infrared radiation and reflect some of it back to the window this will keep the temperature slightly above the condensation point.</p>
<p>Infrared radiation is the same as heat radiation.</p>
<p>Most objects will block and reflect infrared radiation and this is why dew does not form under a tree or under different types of roofs and objects partially covering the ground.</p>
<p>The CO<sub>2</sub> in our atmosphere has a similar effect,absorbing and re emitting the infrared radiation keeping earth warm at night,had it not been for the different greenhouse gasses the temperature changes during the day night cycles had been a lot larger.</p>

CC BY-SA 4.0
2020-07-16T05:15:27.203Z
So effectively it is a form of insulation, right?
Steve
CC BY-SA 4.0
2020-07-16T05:17:34.273Z
yes in a way more like a mirror reflecting the heat from the object.
trond hansen
CC BY-SA 4.0
2020-07-16T16:58:38.553Z
The branch is insulating against conduction and convection - the branch itself will absorb most infrared radiation, causing it to warm up.  It will not be a major reflector of IR radiation.
J...
CC BY-SA 4.0
2020-07-16T04:28:19.857Z
2020-07-16T05:16:45.133Z
2020-07-16T05:16:45.133Z
trond hansen
<p>Last night was pretty chilly here in South East Queensland, Australia.</p>
<p>We woke this morning to condensation on the bedroom windows but noticed something curious.</p>
<p><a href="https://i.sstatic.net/GiEXf.jpg" rel="noreferrer"><img src="https://i.sstatic.net/GiEXf.jpg" alt="Condensation on window" /></a></p>
<p>Where a small branch was touching the window there was no condensation.  What caused this?</p>

<meteorology>
Why did a branch against a window prevent condensation?
Steve
# Why did a branch against a window prevent condensation?

(Asked by: username_0 on 2020-07-16)

Last night was pretty chilly here in South East Queensland, Australia.

We woke this morning to condensation on the bedroom windows but noticed something curious.

[![Condensation on window](https://i.sstatic.net/GiEXf.jpg)](https://i.sstatic.net/GiEXf.jpg)

Where a small branch was touching the window there was no condensation. What caused this?

**Tags:** meteorology


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## 2 answers

### Answer by username_2 on 2020-07-16. Score: 9 | Accepted answer

The branch block outgoing infrared radiation and reflect some of it back to the window this will keep the temperature slightly above the condensation point.

Infrared radiation is the same as heat radiation.

Most objects will block and reflect infrared radiation and this is why dew does not form under a tree or under different types of roofs and objects partially covering the ground.

The CO2 in our atmosphere has a similar effect,absorbing and re emitting the infrared radiation keeping earth warm at night,had it not been for the different greenhouse gasses the temperature changes during the day night cycles had been a lot larger.

> **Comments:**
> **username_0**: So effectively it is a form of insulation, right?  
> **username_2**: yes in a way more like a mirror reflecting the heat from the object.  
> **username_3**: The branch is insulating against conduction and convection - the branch itself will absorb most infrared radiation, causing it to warm up.  It will not be a major reflector of IR radiation.  

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### Answer by username_1 on 2020-07-19. Score: 3

The glass will be receiving heat from the inside and transferring it outside via several mechanisms, both radiant heat in the infrared and conduction/convection by its contact with the warm indoor air and cold outdoor air.

It's difficult to say for sure which loss mechanism is most important in this case, but [the other answer](https://earthscience.stackexchange.com/a/19940/6031) only mentions radiation and as suggested in comments there it's hard to believe that the reduced motion of the air around the branch isn't contributing significantly.

It's also important to point out that lateral heat flow within the glass from the warmer to the colder areas of the glass is also important. If the window were made of the fictitious "transparent aluminum" with high thermal conductivity, it would be a uniform temperature. It's only because the conductivity of the glass is so low that it can support a thermal gradient.


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