

Height of Cumulus Clouds
Name: Jenn
Status: other
Grade: other
Country: USA
Date: Winter 20122013
Question:
Hello, would I be pretty accurate if I estimate the height of the lowest layer of cumulus clouds using the difference between outside temp and dew point temp F divided by 4.4? Would that give me the lowest layer even if its considered to be FEW Octas?
Replies:
Hi Jenn,
Thanks for the question. There should be no need to estimate the height of the layer of cumulous clouds. This data should be available on the Internet at the NOAA web site, or even on aviation web sites.
I hope this helps. Please let me know if you have more questions.
Thanks
Jeff Grell
Hi Jenn,
Yes, in terms of relative height. No, in terms of true height from sea level. The formula you are using is a limited use one for pilots. They are not concerned about true altitude, just relative altitude(the local cloud cover). The following calculates the true altitude, accounting for the altitude of measurement.
Altitude Base Cloud(ABC) is calculated where T = temperature, Dp = dewpoint, ALTm = altitude of the measurement point.
ABC = ((T  Dp) / 4.5) * 1000 + ALTm
This formula is from U. Cal, San Diego
http://aerosols.ucsd.edu/classes/sio217a/sio217aF8Lecture06b.pdf
There is an on line calculator that may be of help at
http://www.csgnetwork.com/estcloudbasecalc.html
Hoping this helps!
Peter E. Hughes, Ph.D. Milford, NH
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Update: November 2011

