Author Topic: What would it take to measure cloud ceilings?  (Read 2298 times)

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Offline Beech33

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What would it take to measure cloud ceilings?
« on: January 20, 2019, 07:45:15 PM »
I assume the ceiling measurements at airports are determined by an automated LIDAR. Does anyone know of a hobbyist version that might be affordable? It wouldn't need to measure above about 3000 feet.
Thanks for any ideas.

Offline vreihen

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Re: What would it take to measure cloud ceilings?
« Reply #1 on: January 20, 2019, 07:59:24 PM »
You missed this in the for-sale section a few weeks ago:

https://www.wxforum.net/index.php?topic=35222.0
WU Gold Stars for everyone! :lol:

Offline Beech33

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Re: What would it take to measure cloud ceilings?
« Reply #2 on: January 20, 2019, 08:14:11 PM »
Dang it !

Offline Old Tele man

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Re: What would it take to measure cloud ceilings?
« Reply #3 on: January 20, 2019, 10:07:31 PM »
Which are you talking about:

Cloud ceilings, the highest portion (tops) of clouds?
Cloud base, the lowest portion (bottoms) of clouds?

If cloud base (CB), just use temp (T) and dewpoint (Td) values to calculate estimate CB yourself:

CB ≈ (T - Td)*1000/4.4 ... in feet, above ground level.
« Last Edit: January 22, 2019, 01:42:05 PM by Old Tele man »
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Offline CW2274

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Offline Beech33

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Re: What would it take to measure cloud ceilings?
« Reply #5 on: January 23, 2019, 03:23:36 PM »
Old Tele man
I am interested in the cloud base not the tops. I used the term ceiling because for aviation flight rules it means the first base of the first broken (5/8 coverage or more) or overcast layer.
Thanks for the equation!

Offline Beech33

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Re: What would it take to measure cloud ceilings?
« Reply #6 on: January 23, 2019, 03:32:20 PM »

Offline CW2274

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Re: What would it take to measure cloud ceilings?
« Reply #7 on: January 23, 2019, 05:11:22 PM »
Thank you for that link! - That is exactly what I am trying to measure.
http://meteorologytraining.tpub.com/14269/css/14269_39.htm
I believe this is basically what Old Tele was referring to for estimating in lieu of a ceilometer.
http://www.flymac.co.uk/tips-and-info/how-to-estimate-cloud-bases-and-heights/

Offline Old Tele man

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Re: What would it take to measure cloud ceilings?
« Reply #8 on: January 23, 2019, 05:25:49 PM »
Thank you for that link! - That is exactly what I am trying to measure.
http://meteorologytraining.tpub.com/14269/css/14269_39.htm
I believe this is basically what Old Tele was referring to for estimating in lieu of a ceilometer.
http://www.flymac.co.uk/tips-and-info/how-to-estimate-cloud-bases-and-heights/

Yes, except that is for degrees-C and the one I posted (FAA) is for degrees-F.

• Wikipedia:  Cloud Base Measurement

The height of the cloud base can be measured using a ceilometer. This device reflects a beam of light off the cloud base and then calculates its distance using either triangulation or travel time.

Alternatively, the cloud base can be estimated from surface measurements of air temperature and humidity by calculating the lifted condensation level (LCL). One method (FAA) for doing this is as follows:

Find the difference between the surface temperature and the dew point. This value is known as the "spread".
Divide the spread by 4.4 (if temperatures are in °F) or 2.5 (if temperatures are in °C), then multiply by 1000. This will give you cloud base in feet above ground level.
Add the results from step (2) to the field elevation to get cloud base above sea level.


• see page 14 in this FAA handbook: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/14_phak_ch12.pdf
« Last Edit: January 23, 2019, 05:41:31 PM by Old Tele man »
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