Topic: ceiling height cloud cover sensor

[yahtah]

I'd like to go beyond the Davis solar detector and do one that reports the cloud bases and percent of sky coverage. I haven't Wiki'ed this yet, but what would it take to do this? I'm still exploring here, so please don't flame me for not having found the answer if this has been discussed before. 

[miraculon]

What you are describing is a "Ceilometer". There is an explanation on Wikipedia. Ceilometer on Wiki
They are quite expensive and powerful, since the laser (or light in the old days) had to be detectable on the bottom of the clouds. The old "rotating beam" type projected a powerful light at the base of the cloud with a rotating vertically shining beacon. The sensor was mounted at some distance and when the sensor detected the light, the height could be calculated from the angle. (basic trig)

Here is a link to Vaisala's Ceilometers: http://www.vaisala.com/en/products/ceilometers/Pages/default.aspx

I would guess that some kind of FAA approval is involved with these.

Greg H.

[Old Tele man]

Depends upon how accurate you need to be:

• If *close-enough* is good enough, then simply use the Dewpoint Depression approximation: H_(ft) ≈ 1000*(T_db - T_dp)/4.4  [note: H is above local ground level]

• If *gnats' ass* is required, then a ceilometer as discussed above is needed.

[ocala]

"gnats ass"
 

[Old Tele man]

"gnats ass"
 

A really BIG birthday balloon with tether-rope that's marked every foot?