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#601545 - 28/12/2001 22:06 Calculating cloudbase height
Foehn Correspondent Offline
Weather Freak

Registered: 01/11/2001
Posts: 517
Loc: Bardon 4065
Hi all,

I was looking at a web site for pilots the other day and came across what I thought was an interesting formula to calculate the approx. height of the cloudbase.

Take the dew point temperature from the outdoor temperature and multiply by 400 to give you the approx. cloudbase height in feet. Did not indicate if this was a height above sea level or above the airfield.

Any comments / thoughts?

Regards

Sparrow
_________________________
If at first you dont succeed call it Version 1.0

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#601546 - 28/12/2001 22:28 Re: Calculating cloudbase height
Andy Offline
Weatherzone Addict

Registered: 29/06/2001
Posts: 1017
Loc: Mid-North Coast, NSW
You can use the following formulae to calculate the height(H) of a cumulus cloud base given surface temperature and dewpoint.

H(meters)=125*(Tc-Tdc)

H(feet)=222(Tf-Tdf)

Note: Tc and Tdc in the first formula are temperature and dewpoint in degrees Celsius. Tf and Tdf in the second formula are temperature and dewpoint in degrees Fahrenheit.

These are not especially accurate. Check out

http://www.weatherwise.org/qr/qry.00.hicloud.html

for some details.

Andy.

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#601547 - 29/12/2001 01:10 Re: Calculating cloudbase height
hoxygt77 Offline
Member

Registered: 09/12/2001
Posts: 199
Loc: Perth
Yeah the dew point depression method of calculating cloud base especially convective clouds works very well on many occasions (ive used it in Melbourne for 9 months using a Vaisala CT12K ceilometer and an F160 trace to use to check the estimation) - it seems to work best when there is some lifting mechanism whether it be heating or forced acent, although it often works often it doesn't and even during seemingly convective situations it fails to work accurately I suppose using this technique with the F160 trace you can find on here combined with a visual estimation based on the known heights of hills etc should give you an accurate cloud base height. smile

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