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 Post subject: Plotting Cloud base
PostPosted: Sat Jul 26, 2008 12:40 pm 
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Joined: Mon Apr 07, 2008 11:42 am
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Has anyone been able to create a plot for this, alternatively can anyone help me in doing this.
with the use of temp and dew point the aprox base of coulds can be calculated. this is what i want to plot.

then of course freezing point would also be useful....

help appreciated....infact desperately needed


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 Post subject:
PostPosted: Tue Jul 29, 2008 11:40 am 
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Location: Roanoke, VA
Playing with the plot model options, CIG doesn't work for you? There is no option for adiabatic calculation of cloud base.

What do you mean by freezing point calculation?


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 Post subject:
PostPosted: Tue Jul 29, 2008 2:52 pm 
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freezing point...it where freezing occurs.

re cloud base, it can be calculated with dew point and temp, is there a way to do this via a script and then plot the outcome to give the cloud base


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 Post subject:
PostPosted: Tue Jul 29, 2008 3:03 pm 
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freezing point: ie point where freezing occurs NB for people who fly.
so we need to plot this.

also coud base this can be determined with a calc with dew point and temp
how can we do this with a script and then plot it?


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 Post subject:
PostPosted: Wed Jul 30, 2008 2:22 am 
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Joined: Thu Apr 24, 2008 9:18 pm
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Location: Grandview, TX 76050
I seriously suggest purchasing RAOB Software ( http://www.raob.com/ ). It has and does all this that you are asking about - plus- SUPPORT.
Best regards,
Jerry


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 Post subject:
PostPosted: Wed Jul 30, 2008 12:15 pm 
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i have had a look, its great, but being able to plot it all over a land map graphically is what i am after otherwise you just see the info per station as apposed to a global outlook.
WG imports the same data as RAOB uses so in theory we should be able to plot with it....in theory....


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PostPosted: Wed May 20, 2009 12:27 pm 
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Joined: Sun Nov 13, 2005 10:03 pm
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Location: Mid-Wales
Sometime ago a request was made for a script for plotting cloud base using the following formula:

Cloud Base ft = ((Temp - Dew point) / 4.4) * 1000

The script is as below:

#Cloud Base script FEET
#CB feet= ((Surface Temp F - Dewpoint F)/4.4) * 1000
ERASE
SFCPLOTMODEL,C:\Documents and Settings\.????..\.????\.??.\.???.\Standard Plot model.sps
ANALYZE, SMLC 4:1000 STOR 4 SDVC 3:4.4 STOR=3 SDIF 1:2 STOR=2 DWPT DEGF STOR=1 TEMP DEGF
ANALYZE, CONT CINT=200 COLOR=100:100:100

Fill in the appropriate ???? with your .SPS file usually in the DA directory.

The formula is only approximate and theoretical so not sure how much use it really is in the 'real' world.

To convert to metres use script below:

#Cloud Base script Metres
#CB metres= (((Surface Temp F - Dewpoint F)/4.4) * 1000)/3.28
ERASE
SFCPLOTMODEL,C:\Documents and Settings\GW8ARR\Local Settings\Application Data\DigitalAtmosphere\Standard Plot model.sps
ANALYZE, SDVC 5:3.28 STOR=5 SMLC 4:1000 STOR 4 SDVC 3:4.4 STOR=3 SDIF 1:2 STOR=2 DWPT DEGF STOR=1 TEMP DEGF
ANALYZE, CONT CINT=50 COLOR=100:100:100

Change CINT as required.

Regards


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PostPosted: Mon Jun 01, 2009 2:54 pm 
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Joined: Tue Dec 16, 2008 11:31 pm
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Hi, the cloud base calculated by the formula mentioned (Henning's formula) holds for convective clouds only, or for a cloud base in a well mixed boundary layer. I know it as SPREAD * 125 = Base in Meters. As you can imagine, layer clouds may form by different processes which are beyond the reach of a simple formula like this.

The depiction of the freezing level on a map is a bit more complicated. I am working on this subject using a combination of RAOB and DA. The charts I am producing can be seen on my HP http://www.wetteruwe.de. It is in German, made for Europe thunderstorms, and still 'heavily under construction'. I am awaiting some improvements of DA for a better accuracy, and the number of charts will increase. The charts appear - if everything runs smoothly - starting 45 min after the radiosonde hours, updates are made till t+2 hours.

Uwe


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