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The Science behind 'Irish' Thunderstorms

  • 08-06-2017 6:40pm
    #1
    Vlak
    Registered Users Posts: 2 ✭


    Hi All,

    Been a lurker on here for quite a while and enjoy the fantastic contributions which many make on here regarding the observations, forecasts, analysing models, etc; however one thing which I haven't seen on here is the analysis of why so many of the storms we get are marginal events, or turn out to be damp squibs!

    I understand there are perhaps many contributing factors into why storms don't materialise but in layman's terms is there a simple general explanation as to why thunderstorms are so few and far between here? When the models set-up runs for storms the analysis seems positive for many thunderstorms; both here and GB, yet I've noticed on dozens of occasions when models make such projections rarely does Ireland see the level of sferic activity that GB does.

    To my untrained eye it seems to me that on many occasions convection is quick to build in intensity but then appears to 'peak' early and then fizzle out. Or alternatively convection builds and strengthens with some impressive 'storms' on the rainfall radars (high intensity of perception) but yet fail to produce sferics? I've tracked several such storms over the radars which are likely to pass over my location and when they do at times the rainfall is very intensive, (and the temp does drop rapidly) but yet fails to produce any thunderstorm activity.

    Would I be right in guessing that many of these intense showers are just on the 'wrong' side to produce thunderstorm activity? What is needed atmospherically to make them on the 'right' side? Is it simply because the rising warm air is 1C - 2C below what is required to make storms fire, or am I being overly simplistic?


Comments

  • #2
    MidMan25
    Closed Accounts Posts: 1,027 ✭✭✭MidMan25


    Nice little basics guide here :)

    http://www.metoffice.gov.uk/learning/learn-about-the-weather/thunder-and-lightning


  • #3
    pedigree 6
    Closed Accounts Posts: 4,559 ✭✭✭pedigree 6


    Basically it's having all air flow up to the troposphere moving in the one direction and having no barriers (inversion layers) for the warm moist air from the earth's surface to get up to the troposphere and to keep the whole cell in one animal of sorts.

    Ideal thunderstorm set up.
    screenshot_1.png

    Inversion layers in red and different wind directions in blue.
    No thunderstorm.:(
    screenshot_1.png

    Edit: Correct me if i'm wrong but just to kick this thread off.
    I wouldn't mind hearing from the seasoned posters.


  • #4
    pedigree 6
    Closed Accounts Posts: 4,559 ✭✭✭pedigree 6


    Right I hope meteorite doesn't mind me borrowing this tephigram image? ;)

    This was a forecasted soundings for I think somewhere in the midlands yesterday.
    screenshot_1.png

    Now the one thing to look at is the red line for temperature.
    Notice how smooth and flowing it is. The same goes for the green line the wet bulb temperature.
    What does that tell you?
    That there's no inversion layers.

    What is an inversion layer of air?
    It is a layer of warmer air above a cooler body of air.

    What does this matter for?
    Well it matters because moisture is always attracted to a cooler surface or air.
    When the temperature in the air is always getting cooler the higher you get up above the earth's surface, the moisture will continue to rise to meet that cooler air. But if that moisture meets a warmer layer of air above the cooler air that it's just come from. It will stay in the cooler air and not move into the warmer air.

    So back to the tephigram picture.
    screenshot_1.png
    The moisture will only rise as far as the red mark I put in.
    A good idea to read the temperature readings for the different heights in altitude is to look at the 0 degree celcius mark on the bottom of the picture and turn the picture so that the blue line coming off it sloping to the right is horizontal as you look at it. Easier I find.

    Now here is todays Met Eireann tephigram for Valentia.
    (Hope I don't get sued for copyright).
    screenshot_1.png
    You can see the difference in the two charts.
    This is more zig zaggy. I think the green line wet bulb temperature needs to be a constant downward trend as well as the red line air temperature to have optimum lift of moisture and if you have a rise in temperature in both green and red lines that's an inversion layer.

    That's my taking on it all anyway.:)


  • #5
    Iancar29
    Registered Users Posts: 5,068 ✭✭✭Iancar29


    Vlak wrote: »
    Hi All,

    Been a lurker on here for quite a while and enjoy the fantastic contributions which many make on here regarding the observations, forecasts, analysing models, etc; however one thing which I haven't seen on here is the analysis of why so many of the storms we get are marginal events, or turn out to be damp squibs!


    We are an Island surrounded by a large mass of water, we are suppressed by it alot. We don't regularly generate sufficient surface based heating. We also don't get this paired up with a warm moist tropical air mass. These then with the correct position and upper troughs to give severe dynamics just doesn't happen over here as regularly as on the continent.


  • #6
    pedigree 6
    Closed Accounts Posts: 4,559 ✭✭✭pedigree 6


    This is a handy guide for reading tephigrams and predicting thunderstorms from the charts.

    http://www.blackmountainsgliding.co.uk/groundschool/gsdocs/tg/tephigrams.pdf


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