Author Topic: Measuring outdoor temp from inside  (Read 319 times)

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Offline DesertBlue

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Measuring outdoor temp from inside
« on: October 08, 2021, 09:56:31 PM »
Hi all – Are there any devices that can measure outdoor temperature from indoors? I'm thinking maybe through a window. It should be possible physics-wise, but I've not heard of any products.

Thanks.

Offline sky_watcher

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Re: Measuring outdoor temp from inside
« Reply #1 on: October 08, 2021, 11:51:13 PM »
Put a thermometer outside and look at it through the window using binoculars. :-)

More seriously, any attempt to measure temperature through a window is very unlikely to give a good reading as normal window glass is partly reflective and partly absorbs the light including infrared passing through it.
“The more a man knows, the more willing he is to learn. The less a man knows, the more positive he is that he knows everything...” ― Robert G. Ingersoll

Offline Splitrail

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Re: Measuring outdoor temp from inside
« Reply #2 on: October 10, 2021, 10:09:29 AM »
Hi all – Are there any devices that can measure outdoor temperature from indoors? I'm thinking maybe through a window. It should be possible physics-wise, but I've not heard of any products.

Thanks.

Why :-|?

Offline SteveFitz1

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Re: Measuring outdoor temp from inside
« Reply #3 on: October 10, 2021, 10:35:50 AM »
Get an indoor device with an outdoor sensor to measure the outside temp. Then it's very easy to see the temp. :=_

Offline DaleReid

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Re: Measuring outdoor temp from inside
« Reply #4 on: October 10, 2021, 11:23:09 AM »
I guess I failed to find a motivation in your request, as to you live in a Faraday box or something where perfectly good RF telemetry from even el-cheapo sensors work just fine.

Heck, I even saw a remote reading device for indoor, outdoor temp and indoor humidity for under $10 at a local grocery store of all things.

Are you just wanting a Rube Goldberg device to say you did it or is there some limitation to proven, cheap, and readily available devices that won't work for this purpose?

Just curious.
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Offline Splitrail

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Re: Measuring outdoor temp from inside
« Reply #5 on: October 10, 2021, 11:54:27 AM »
I guess I failed to find a motivation in your request, as to you live in a Faraday box or something where perfectly good RF telemetry from even el-cheapo sensors work just fine.

Heck, I even saw a remote reading device for indoor, outdoor temp and indoor humidity for under $10 at a local grocery store of all things.

Are you just wanting a Rube Goldberg device to say you did it or is there some limitation to proven, cheap, and readily available devices that won't work for this purpose?

Just curious.




Holy cow!
Look at his first post!
https://www.wxforum.net/index.php?topic=42739.msg436098#msg436098

Offline DesertBlue

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Re: Measuring outdoor temp from inside
« Reply #6 on: October 12, 2021, 12:41:38 PM »
I guess I failed to find a motivation in your request, as to you live in a Faraday box or something where perfectly good RF telemetry from even el-cheapo sensors work just fine.

Heck, I even saw a remote reading device for indoor, outdoor temp and indoor humidity for under $10 at a local grocery store of all things.

Are you just wanting a Rube Goldberg device to say you did it or is there some limitation to proven, cheap, and readily available devices that won't work for this purpose?

Just curious.

It's mostly just scientific / engineering curiosity. It would be medium to high level cool. I was reading about the retirement of some American and Japanese weather satellites, and the newer models replacing them. And I wondered if, since we can measure all sorts of weather variables from hundreds or thousands of miles away, depending on the orbit, we damn well ought to be able to measure it from a few feet, and through minor barriers.

There are all sorts of potential methods beyond some kind of direct IR targeting, like measuring properties of the window itself in reference to known baseline characteristics and other parameters, properties of other building materials, reference outdoor objects in the field of view, indoor temperature movements in concert with some of those other variables, maybe some "cheating" approaches where you take nominal temperatures for the locality from weather data sources/the web and integrate with some of those other variables, etc. It wouldn't be limited to IR or other spectra, or traditional thermometer sensors – sonic and ultrasonic approaches might be possible through various media, machine vision, a few others.

Offline sky_watcher

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Re: Measuring outdoor temp from inside
« Reply #7 on: October 12, 2021, 03:30:34 PM »
It's mostly just scientific / engineering curiosity. It would be medium to high level cool. I was reading about the retirement of some American and Japanese weather satellites, and the newer models replacing them. And I wondered if, since we can measure all sorts of weather variables from hundreds or thousands of miles away, depending on the orbit, we damn well ought to be able to measure it from a few feet, and through minor barriers.
Measuring is generally relatively easy. Making that measurement meaningful is always the issue. For example, let's say that you are desperate to read the temperature through the window using infrared. You would need to calibrate the transmission characteristics of the glass - and the self heating characteristics of the glass in the atmosphere. You would also need to make sure that the window never gets dirty or wet to stuff up said calibration.

Would you be willing to pay for this AND do the necessary cleaning to ensure every reading is accurate? I suspect not, especially when someone has already has a sensor that is calibrated for use in the air AND for just a couple of dollars can transmit the reading through the glass without affecting the reading.

“The more a man knows, the more willing he is to learn. The less a man knows, the more positive he is that he knows everything...” ― Robert G. Ingersoll

Offline KathyLauren

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Re: Measuring outdoor temp from inside
« Reply #8 on: October 13, 2021, 08:21:56 AM »
Taking a temperature reading through glass is problematic, because most window glass is opaque to IR. 

When I was a volunteer firefighter, one of the required skills was being able to use a thermal imaging camera (TIC).  A TIC will show an image of the thermal IR sources in a scene.  It includes a calibrated spot sensor that will measure and display the temperature of a small spot in the centre of the scene.  It is useful in firefighting to measure, for example, the temperature of a chimney, to determine if there is fire inside it.

If you point the TIC at a window, you see only the glass.  You don't see thermal signatures from the other side of the window.  The spot sensor displays the temperature of the glass, not the temperature of objects on the other side it. 

If you were to try to invent a remote sensor to read the temperature of objects outside a building, part of the invention would have to be the window that it looks out of, since an ordinary window will not work.

 

anything