Skip to content

Why last nights thunder was so loud.

2014-02-19_8-20-54.png

As forecasted we got those thunder showers around 2-4am this morning. What was  shocking and startling to so many was just how loud the thunder was. The storms were not very strong at all and as thunderstorms go they really didn’t produce a larger than average amount of lightning. So what was going on?

These storms were what we call “Elevated” thunderstorms. Which means they started their lift from where the warm front was above the ground and not from the ground itself like an average thunderstorm. These average thunderstorms we call “surface” based storms form when it’s warm and humid at the ground. The average storm starts it’s lift at the surface for this reason.

Why Inversions Matter:

Last night we had an temperature inversion. When looking at the temperature profiles of the atmosphere last night we look at what we call soundings. These are produced by weather balloons but also satellites and model data can produce similar soundings. The sounding from Greensboro this morning and the forecasted sounding from 3 am this morning both showed a temperature inversion. Which means it was actually warmer around 1,000-5,000’ than at the ground. This inversion was likely the warm front moving in. These inversions can trap cold air below them, sometimes pollution and in this case it helped trap sound.

2014-02-19_8-11-37

So what happened last night?:

The elevated thunderstorms produced lightning which created the sound of thunder. Normally with a thunderstorm these thunder sound waves would dissipate and propagate in all directions. Last night due to the inversion the sound waves got trapped near the ground. This was the equivalent of setting off fireworks in a closed room verses outside in the open.

2014-02-19_8-20-54.png

These inversions can also allow for the sound waves to travel very far distances as well. This is called atmospheric ducting and works on radio waves and other waves. These inversions can make you pick up radio stations and TV stations over the air at very long distances. They are also the main reason we get ground clutter on our First Warn Doppler Radar at night when the sky is clear.

atmospheric_sound_ducting

  • Cloddy

    This reminds me of a similar storm one April in Bracknell, UK, nearly thirty years ago. This came in from the east along the Thames Valley from London with cooler air from the NE undercutting it. I was just leaving work when one flash and bang occurred and another followed when I’d walked about a quarter-mile home. I dashed for the nearest pub for cover. Nothing unusual about that, I suppose.

    A week or so later, someone was telling me he was working at Farnborough at the time. It was a sunny day but suddenly he glimpsed a flash out of the corner of his eye. He counted and got to 45 when he heard the thunder and the windows of the office rattled. A little while later he heard the second one and got to 44 as the thunder and window-rattling occurred. From these timings, he realised the flashes were about 11 miles away and probably near Bracknell. As it was during the time of the IRA bombing campaign, his first guess as to the cause was incorrect.

    Normally, you wouldn’t hear thunder from that distance – I’ve been under a few high-level storms where any thunder from frequent overhead lightning was mostly inaudible – but the ducting in this case was sufficient for the shock-wave to even rattle windows. Quite remarkable.

  • http://www.obsessedwithconformity.com Jim Mitchem

    That was fascinating. And yes, I’ve always wondered why i can hear WFAN sometimes all the way down to Florida.