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Old 11-04-2008, 06:03 PM
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Default Formula for determining cloud bases

Does anyone have the formula for determing the cloud bases?
Think I heard something like this: Temperature minus dewpoint divided by 4.4, then multiplyed by 1000. It did seem to work.......
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Old 11-04-2008, 06:13 PM
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Originally Posted by packageflyer View Post
Does anyone have the formula for determing the cloud bases?
Think I heard something like this: Temperature minus dewpoint divided by 4.4, then multiplyed by 1000. It did seem to work.......

I believe that's correct, and I want to say for some reason or another that only works with cumulus bases. But I could be wrong.
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Old 11-04-2008, 07:23 PM
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Yeah this seems to be the same formula I remember. I also remember that there was something in there about cumulus bases but I'm not 100% about that either. Hehe multipilot is an @$$ chief CFI. Sweet.
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Old 11-05-2008, 05:01 AM
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I believe its 4.4 for Fahrenheit and 2.5 for Celsius
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Old 11-05-2008, 09:59 AM
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I use A+T+I+S...works great.
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Old 11-05-2008, 12:20 PM
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Originally Posted by Krafty1 View Post
I believe its 4.4 for Fahrenheit and 2.5 for Celsius
think it's 2.2 for celcius?

edit: no I was wrong
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Old 11-05-2008, 05:31 PM
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temp - DP X either 200 (if using C) or 400 (if using F)
If reading temps from a digital ATIS, use the T000000 series of numbers for the exact temp spread.... IE temp 6 C and Dewpoint 7 C in the ATIS can be found again at the end as T056074 meaning 5.6 degrees C temp and 7.4 degrees C on the DP... the difference being 1.8. 1.8 x 200 = 360 feet estimated bases... with just the ATIS 6/7 you'd come up with 200 for the bases and be significantly off....

yes, if you HAVE to be mr perfect, use the 4.4 and 2.2 OR 440 feet and 220 feet per degree.
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Old 11-05-2008, 07:47 PM
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Originally Posted by Mason32 View Post
..IE temp 6 C and Dewpoint 7 C in the ATIS can be found again at the end as T056074 meaning 5.6 degrees C temp and 7.4 degrees C on the DP...
And that would give you a relative humidity of how much?
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Old 11-06-2008, 07:51 PM
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Yup, it's (Temperature-Dew Point)/2.5 x 1000

For example, 35 degree Temp, 30 degree DP:

(35-30) = 5 . . . 5/2.5 = 2 . . . 2 x 1000 = 2000 AGL base of clouds
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Old 11-07-2008, 04:06 AM
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Keep it simple. I use the T.L.A.R method. It is easy and works with most every aviation calculation.

That Looks About Right
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