View Full Version : How to calculate CAPE?
Aric Cylkowski
10-02-2005, 08:44 PM
Been trying to find a good method of calculating CAPE. If anyone can help me out, I would gladly appreciate it.
Jeff Snyder
10-02-2005, 08:55 PM
You can't really do it w/o the help of a computer. If you look at a ton of skew-Ts, you can probably begin to eyeball/estimate CAPE pretty well. I suppose you could print out a skew-t and use tiny pieces of paper to "estimate CAPE" by doing some "calibration" beforehand. For example, all the paper shreds equal 5000 CAPE, so if you only use 1/2 of the scraps to fill in the area between the parcel trace and the environment, then you could estimate the sounding (for the parcel you choose) to have about 2500 j/kg CAPE. I suppose you could use your calculator to numerically solve for CAPE by going through LFC to EQ at, say 250m increments), but that's not really practical.
Scott Olson
10-02-2005, 09:48 PM
Here is a method:
http://bangladeshtornadoes.org/liftedcalc.html
Jeff Snyder
10-02-2005, 10:16 PM
Originally posted by Scott Olson
Here is a method:
http://bangladeshtornadoes.org/liftedcalc.html
Scott,
That page describes how to "forecast" the Lifted Index (LI), not CAPE. Just FYI :)
Glen Romine
10-02-2005, 10:25 PM
You can rather easily calculate LI though - and it is a quite reasonable ballpark surface-based instability estimate for the typical sounding. Plenty of resources on the web for how to calculate this (do a google search). Reality is that there is insignificant value in getting exact CAPE calculations - to the nearest 500 J/Kg will do most days, and LI for a typical environment can get you that level of accuracy.
Glen
Scott Olson
10-03-2005, 04:02 PM
Originally posted by Jeff Snyder+--><div class='quotetop'>QUOTE(Jeff Snyder)</div><!--QuoteBegin-Scott Olson
Here is a method:
http://bangladeshtornadoes.org/liftedcalc.html
Scott,
That page describes how to "forecast" the Lifted Index (LI), not CAPE. Just FYI :)[/b]
I know, it's for the LI but figured it might be helpful.
Chris Lott
10-03-2005, 10:07 PM
Maybe this will help. :D
http://www.eos.ubc.ca/courses/atsc201/A201...adings.html#ESO (http://www.eos.ubc.ca/courses/atsc201/A201Resources/SoundingTutorial1/SoundingTutorial1Readings.html#ESO)
Once you click this link, down near the bottom of the page it explains how to calculate CAPE.
Bobby Eddins
10-03-2005, 11:47 PM
Here's another with a fomula. Pan down and look for CAPE.
http://www.crh.noaa.gov/lmk/soo/docu/indices.htm
Aric Cylkowski
10-04-2005, 07:56 AM
Thank you guys for the help.
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