Author Topic: Inferring cloud cover from VP2 solar data  (Read 242 times)

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Offline miraculon

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Inferring cloud cover from VP2 solar data
« on: November 01, 2018, 11:55:05 AM »
I saw this fancy cloud cover instrument, which is more expensive than I can justify: https://diffractionlimited.com/product/boltwood-cloud-sensor-ii/

Just watching my solar plots on a daily basis, got me to wondering if there was some way to compare a "clear sky" day based on historical data and determine roughly the cloud cover. I am thinking something very basic like "clear", "partly cloudy" and "overcast".

For example, this recent chart shows a clear day the first day, followed by partly cloudy days.

Maybe the database work it too complex. This is beyond my programming skills, but I was wondering if anyone had attempted something like this.

Greg H.


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Offline Bushman

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Re: Inferring cloud cover from VP2 solar data
« Reply #1 on: November 01, 2018, 12:28:09 PM »
Stick your head out the window and look.  :)   Seriously though check this for info:  http://web.mit.edu/parmstr/Public/NRCan/rp418.pdf

Offline pfletch101

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Re: Inferring cloud cover from VP2 solar data
« Reply #2 on: November 03, 2018, 01:37:01 PM »
I saw this fancy cloud cover instrument, which is more expensive than I can justify: https://diffractionlimited.com/product/boltwood-cloud-sensor-ii/

Just watching my solar plots on a daily basis, got me to wondering if there was some way to compare a "clear sky" day based on historical data and determine roughly the cloud cover. I am thinking something very basic like "clear", "partly cloudy" and "overcast".

For example, this recent chart shows a clear day the first day, followed by partly cloudy days.

Maybe the database work it too complex. This is beyond my programming skills, but I was wondering if anyone had attempted something like this.

Greg H.
It's not really a database issue. Insolation and cloud cover don't have a terribly linear relationship. You can have reasonably good insolation with 100% coverage by fairly thin cloud, and you can have normal measured insolation for a clear sky despite thick cloud cover confined to the part of the sky that doesn't contain the sun (and, of course, vice versa).
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