<p><a href="https://astronomy.stackexchange.com/a/55710/7982">My answer to <em>Could UV-A imaging sensor reasonably see a total eclipse in progress through clouds?</em></a> suggests that while clouds blocking visible light observation of the (partially) eclipsed solar disk would also likely block near UV viewing, there's a chance that there might be some transmission in the 10 micron &quot;window&quot; in the thermal infrared.</p>
<p>My original hypothesis that the water droplets of clouds were sub-wavelength even for visible light (and so Rayleigh's <span class="math-container">$1/\lambda^4$</span> would help for 10 micron transparency) was <a href="https://astronomy.stackexchange.com/a/55713/7982">nicely shot down by another answer</a> but I'm still wondering if <a href="https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes#Overall" rel="noreferrer">terrestrial thermal IR viewing observatories</a> can sometimes see through clouds, or at least haze, that would obscure visible light (the way these wavelengths can see through galactic dust). So I'd like to ask:</p>
<p><strong>Question:</strong> Can terrestrial infrared telescopes see through clouds or haze, sometimes at least?</p>
<p>Related:</p>
<ul>
<li><a href="https://astronomy.stackexchange.com/q/18791/7982">What is precipitable water vapor in millimeter-wave radioastronomy and how is it measured?</a></li>
</ul>
<hr />
<p><a href="https://i.sstatic.net/fPe8z.png" rel="noreferrer"><img src="https://i.sstatic.net/fPe8z.png" alt="https://commons.wikimedia.org/wiki/File:Atmospheric_Transmission.png" /></a></p>
<p><a href="https://commons.wikimedia.org/wiki/File:Atmospheric_Transmission.png" rel="noreferrer">Source and detailed explanation</a></p>

CC BY-SA 4.0
2024-01-11T07:53:30.487Z
good question, I support
ayr
CC BY-SA 4.0
2024-01-11T08:24:23.167Z
I don't have an answer, but when doing a google search for "thermal camera cloud" I get a lot of thermal images where you see clouds. So clouds will be transmitted better than in the Vis, but it doesn't seem to be a magic trick making all clouds invisible. Plus, water absorbs Infrared, so there will be attenuation by absorption (in addition to scattering) as well.
Charles Tucker 3
CC BY-SA 4.0
2024-01-11T08:49:49.173Z
Probably limited. See https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes which contains ground-based facilities
planetmaker
CC BY-SA 4.0
2024-01-11T09:01:25.570Z
@CharlesTucker3 certainly clouds will be visible in thermal IR against the night sky since they're warmer, and something can't be simultaneously radiating and transparent at the same wavelength, but perhaps in your other pocket there's a somewhat narrow bandpass filter around 10 microns where water absorbs and radiates the weakest.
uhoh
CC BY-SA 4.0
2024-01-11T09:45:35.703Z
@uhoh That's a good point. I wonder if that could improve vision through fog on Earth as well. Would help autonomous cars for example...
Charles Tucker 3
CC BY-SA 4.0
2024-01-11T10:21:33.050Z
@CharlesTucker3 somewhat relatd: [Is the visible light spectrum from "red-hot glass" at least close to Blackbody Radiation?](https://physics.stackexchange.com/q/254099/83380) and [Kirchhoff's law for glass and transparent crystals; how exactly do hot transparent materials produce so much visible thermal radiation?](https://physics.stackexchange.com/q/606316/83380)
uhoh
CC BY-SA 4.0
2024-01-13T04:34:13.030Z
This page by FLIR  seems to sum up as 'it depends' https://www.flir.com.au/discover/rd-science/can-thermal-imaging-see-through-fog-and-rain/ and matches my observations with them that some environments IR cameras drastically improve the seeing and others are somewhat worse. Do not have the optics chops to convert those graphs into an answer so you are welcome to do so if it makes sense to you.
GremlinWranger
CC BY-SA 4.0
2024-01-13T05:38:30.110Z
@GremlinWranger *Very interesting, Thanks!* It links to paywalled [Simulation of infrared detection range at fog conditions for Enhanced Vision Systems in civil aviation](https://www.sciencedirect.com/science/article/abs/pii/S1270963803000968) and here's a glossy version of your link: [Seeing through fog and rain with a thermal imaging camera; Metrological effects of Fog & Rain upon IR Camera Performance](http://www.flirmedia.com/MMC/CVS/Tech_Notes/TN_0001_EN.pdf)
uhoh
CC BY-SA 4.0
2024-01-13T05:38:43.010Z
@GremlinWranger and here are some  similar treatments; Josefine Corné thesis: [Investigation of IR transmittance in different weather conditions and simulation of passive IR imaging for flight scenarios](https://www.aphys.kth.se/polopoly_fs/1.934189.1600690015!/Thesis_Josefine_Ulrika.pdf) and [IR measurements and image processing for enhanced vision systems in civil aviation](https://www.researchgate.net/publication/224794744_IR_measurements_and_image_processing_for_enhanced_vision_systems_in_civil_aviation) I have a hunch that as you sort-of suggest, the answer may boil down to "sometimes".
uhoh
<observational-astronomy><atmospheric-effects><infrared>
Can terrestrial infrared telescopes see through clouds or haze, sometimes at least?
uhoh
# Can terrestrial infrared telescopes see through clouds or haze, sometimes at least?

(Asked by: username_0 on 2024-01-11)

[My answer to *Could UV-A imaging sensor reasonably see a total eclipse in progress through clouds?*](https://astronomy.stackexchange.com/a/55710/7982) suggests that while clouds blocking visible light observation of the (partially) eclipsed solar disk would also likely block near UV viewing, there's a chance that there might be some transmission in the 10 micron "window" in the thermal infrared.

My original hypothesis that the water droplets of clouds were sub-wavelength even for visible light (and so Rayleigh's $1/\lambda^4$ would help for 10 micron transparency) was [nicely shot down by another answer](https://astronomy.stackexchange.com/a/55713/7982) but I'm still wondering if [terrestrial thermal IR viewing observatories](https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes#Overall) can sometimes see through clouds, or at least haze, that would obscure visible light (the way these wavelengths can see through galactic dust). So I'd like to ask:

**Question:** Can terrestrial infrared telescopes see through clouds or haze, sometimes at least?

Related:

* [What is precipitable water vapor in millimeter-wave radioastronomy and how is it measured?](https://astronomy.stackexchange.com/q/18791/7982)

---

[![https://commons.wikimedia.org/wiki/File:Atmospheric_Transmission.png](https://i.sstatic.net/fPe8z.png)](https://i.sstatic.net/fPe8z.png)

[Source and detailed explanation](https://commons.wikimedia.org/wiki/File:Atmospheric_Transmission.png)

**Tags:** observational-astronomy, atmospheric-effects, infrared

> **Comments:**
> **username_1**: good question, I support  
> **username_2**: I don't have an answer, but when doing a google search for "thermal camera cloud" I get a lot of thermal images where you see clouds. So clouds will be transmitted better than in the Vis, but it doesn't seem to be a magic trick making all clouds invisible. Plus, water absorbs Infrared, so there will be attenuation by absorption (in addition to scattering) as well.  
> **username_3**: Probably limited. See https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes which contains ground-based facilities  
> **username_0**: @username_2 certainly clouds will be visible in thermal IR against the night sky since they're warmer, and something can't be simultaneously radiating and transparent at the same wavelength, but perhaps in your other pocket there's a somewhat narrow bandpass filter around 10 microns where water absorbs and radiates the weakest.  
> **username_2**: @username_0 That's a good point. I wonder if that could improve vision through fog on Earth as well. Would help autonomous cars for example...  
> **username_0**: @username_2 somewhat relatd: [Is the visible light spectrum from "red-hot glass" at least close to Blackbody Radiation?](https://physics.stackexchange.com/q/254099/83380) and [Kirchhoff's law for glass and transparent crystals; how exactly do hot transparent materials produce so much visible thermal radiation?](https://physics.stackexchange.com/q/606316/83380)  
> **username_4**: This page by FLIR  seems to sum up as 'it depends' https://www.flir.com.au/discover/rd-science/can-thermal-imaging-see-through-fog-and-rain/ and matches my observations with them that some environments IR cameras drastically improve the seeing and others are somewhat worse. Do not have the optics chops to convert those graphs into an answer so you are welcome to do so if it makes sense to you.  
> **username_0**: @username_4 *Very interesting, Thanks!* It links to paywalled [Simulation of infrared detection range at fog conditions for Enhanced Vision Systems in civil aviation](https://www.sciencedirect.com/science/article/abs/pii/S1270963803000968) and here's a glossy version of your link: [Seeing through fog and rain with a thermal imaging camera; Metrological effects of Fog & Rain upon IR Camera Performance](http://www.flirmedia.com/MMC/CVS/Tech_Notes/TN_0001_EN.pdf)  
> **username_0**: @username_4 and here are some  similar treatments; Josefine Corné thesis: [Investigation of IR transmittance in different weather conditions and simulation of passive IR imaging for flight scenarios](https://www.aphys.kth.se/polopoly_fs/1.934189.1600690015!/Thesis_Josefine_Ulrika.pdf) and [IR measurements and image processing for enhanced vision systems in civil aviation](https://www.researchgate.net/publication/224794744_IR_measurements_and_image_processing_for_enhanced_vision_systems_in_civil_aviation) I have a hunch that as you sort-of suggest, the answer may boil down to "sometimes".  

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## 0 answers

