#1147897  06/12/2012 22:50
Re: How much energy is in a thunderstorm?
[Re: Chris #3]

Weather Freak
Registered: 16/11/2006
Posts: 751
Loc: Melbourne, Victoria

Well, its surprisingly not that difficult to work out. Forgive me for a little maths and some kludging but I can't write it out in full:
CAPE is a measure of energy of an air parcel, yielded to a thunderstorm. Its measured in J/kg so we can use this if we know the volume of air being moved through a thunderstorm at any one time and extrapolate for its life cycle.
So lets assume that our hypothetical thunderstorm is pretty standard for the midlatitudes, standing 15km tall, maybe 10x10kms horizontal directions, and we will assume an instaneous timeframe
This gives us a volume of 15x10x10 = 1500km^3 Or 1.5x10^12 m^3
Now lets assume a modest density for air, which is variable with height (decreasing), so hence in the US standard atmosphere at the surface you have 1.225 kg/m^3, at altitude a 5th of the pressure, so hence lets take a mean value of say 0.75kg/m^3 for the depth the cloud.
So by mass 1.125x10^12 kg.
Assume all energy is yielded and the CAPE is a modest 1500J/kg: 1.687 Terajoules
Energy from Hiroshima nuclear detonation = 67TJ
Average length of life for a thunderstorm say 60 minutes assuming mass continuity and parcels of similar CAPE = easily greater than the energy released by a nuclear weapon. Now, consider higher CAPE and bigger storms  the estimate would suggest this is certainly reasonable. I could go further, (based on maximum updraft potential to work out the mass flux) but I think you get the idea  there is alot of energy in the phase changes from vapour to liquid to ice.
Edited by Severely Tall (06/12/2012 22:52)

Top




#1147898  06/12/2012 22:56
Re: How much energy is in a thunderstorm?
[Re: Severely Tall]

Meteorological Motor Mouth
Registered: 29/11/2009
Posts: 8400
Loc: Blair Athol, SA

Damn, ST beat me to it, had the maths going and all! haha. But yes, it's more than possible. The huge difference here is the timespan in which the energy is released. Like ST said, in a thunderstorm, the energy is released over minutes to hours, whereas a nuke, it's all released in a matter of seconds, creating a huge shockwave. If you could get a thunderstorm to release ALL of it's energy at once, it'd be just as, if not more devastating as a nuke, depending on the size of the storm, of course.
Using the CAPE is a great way to do it, I was working on figures around lightning, which is what CAPE ultimately determines but in a much more accurate way.

Top




#1147899  06/12/2012 23:06
Re: How much energy is in a thunderstorm?
[Re: Severely Tall]

Weatherzone Addict
Registered: 08/02/2009
Posts: 1891
Loc: Semaphore SA

Well, its surprisingly not that difficult to work out. Forgive me for a little maths and some kludging but I can't write it out in full:
CAPE is a measure of energy of an air parcel, yielded to a thunderstorm. Its measured in J/kg so we can use this if we know the volume of air being moved through a thunderstorm at any one time and extrapolate for its life cycle.
So lets assume that our hypothetical thunderstorm is pretty standard for the midlatitudes, standing 15km tall, maybe 10x10kms horizontal directions, and we will assume an instaneous timeframe
This gives us a volume of 15x10x10 = 1500km^3 Or 1.5x10^12 m^3
Now lets assume a modest density for air, which is variable with height (decreasing), so hence in the US standard atmosphere at the surface you have 1.225 kg/m^3, at altitude a 5th of the pressure, so hence lets take a mean value of say 0.75kg/m^3 for the depth the cloud.
So by mass 1.125x10^12 kg.
Assume all energy is yielded and the CAPE is a modest 1500J/kg: 1.687 Terajoules
Energy from Hiroshima nuclear detonation = 67TJ
Average length of life for a thunderstorm say 60 minutes assuming mass continuity and parcels of similar CAPE = easily greater than the energy released by a nuclear weapon. Now, consider higher CAPE and bigger storms  the estimate would suggest this is certainly reasonable. I could go further, (based on maximum updraft potential to work out the mass flux) but I think you get the idea  there is alot of energy in the phase changes from vapour to liquid to ice.
Thanks Severely Tall much appreciated! I've been wanting to believe that fact for a long time, and have even stated it to people in the past  was just telling someone today then felt guilty because it sounds like one of those 'facts'. Long lasting thunderstorms bigger than Hiroshima? Yeah didn't think that would be a problem. Was more unsure about 'moderate' thunderstorms, and up against the bigger thermonuclear weapons (Like the Russians crazy 100mt bomb  the one that they tested at half strength).. 100000 Kiloton vs. Hiroshima 16 Kiloton. The fact that TStorms can be as powerful as that is awesome anyway. I guess it's got a lot to do with the way it releases it's energy, and how it's over a long period of time (relatively) Might have a go at calculating, you made it look so easy

Top




#1147901  06/12/2012 23:30
Re: How much energy is in a thunderstorm?
[Re: Severely Tall]

Weatherzone Addict
Registered: 08/02/2009
Posts: 1891
Loc: Semaphore SA

I could go further, (based on maximum updraft potential to work out the mass flux) but I think you get the idea  there is alot of energy in the phase changes from vapour to liquid to ice.
Yep I think you and Things are right. I know where to come if I have any other of these kinds of questions. Not many forums where you get quality responses from people who know what they're talking about.

Top




#1147908  07/12/2012 00:16
Re: How much energy is in a thunderstorm?
[Re: Chris #3]

Weather Freak
Registered: 09/08/2009
Posts: 584
Loc: SE QLD

Interesting conversation, but this isn't really comparing like for like though. If the nuclear bomb was able to go off continuously for 60min it would have vastly more energy than the storms based on those numbers.

Top





0 registered (),
49
Guests and
3
Spiders online. 
Key:
Admin,
Global Mod,
Mod


29631 Members
32 Forums
23943 Topics
1495607 Posts
Max Online: 2925 @ 02/02/2011 22:23


