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Author Topic: Background on how to estimate the night sky conditions  (Read 1179 times)

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Offline mihec

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Background on how to estimate the night sky conditions
« on: February 09, 2017, 08:26:26 PM »
Hi all,
I've been using a temperature sensor in a jar for a while now and am fascinated how good this thing works. It's really really simple...
I wonder what is the background (theory) of this measurement principle. Why is the temperature in a jar lower at clear sky? And why it gets closer at cloud cover?
I do understand how this same jar can be used as a simple solar sensor but I can't imagine what makes such temperature difference at night.

Offline niko

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Re: Background on how to estimate the night sky conditions
« Reply #1 on: February 09, 2017, 09:18:58 PM »
Basically because without clouds the relatively warm sensor loses (radiates) heat to space, which is very cold, clouds are much warmer. Scientifically it's Terrestrial Radiative Cooling, see this Wikipedia article.

 

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