Friday, March 30, 2012

"Thunderquake"-- very loud thunder

(ABOVE: Richard Waters took this pic of an approaching storm last week near Broken Arrow. Beautiful!!)



Several KJRH viewers emailed us last week about the incredible thunder from the recent stormy weather.

One viewer called the lightning and thunder "super bolts" while another referred to the booming thunder as "thunderquakes."

So what happened? Let's start with the basics:

As you know thunder is the noise produced by the rapid heating from lightning.

Many factors contribute to the sound of thunder. The main culprits are: your distance from the lightning, temperature and voltage of the lightning, precipitation and clouds, temperature profile near and above the ground, length of the strike, strike multiplicity and polarity.

(ABOVE: I took this pic after mowing the backyard. The recent heavy rain helped turn the yard green. The clover is covering up the dog holes too!)


Now, in layman's terms, here's the deal: thunder will usually sound louder to you if:

- 1.) little to no rain is falling
- 2.) widespread, overcast clouds are present
- 3.) temperatures above the ground are warmer than ground-level temperatures

In detail... 1.) Rain, especially heavy rain, helps reduce and muffle thunder's sound waves. For example, during heavy rain you might only hear thunder from lightning a few miles a way. Before and after the rain, thunder can be apparent from 10 miles away or more.

2) The cloud explanation is more complicated.

Stratus type rain clouds usually have less lightning compared to cumulonimbus storms. Due to the lack of stronger rising motion in flat, stratus clouds, the charge separation isn't as intense, and fewer cloud- to- ground lightning strikes occur. However, a higher percentage of those strikes are positively charged.

A positive charge means the bolt of lightning you see is much more intense. Positively charged electrical channels are hotter and "last longer" than negative charges. This causes much louder thunder.

And if stratus/overcast conditions are present, then the thunder can also linger as the clouds somewhat reflect the sound waves.

3) Inversion-- this occurs more during Summer. An inversion means that air temperatures rise with height instead of the usual cooling.

If storms can form within this environment, the inversion can greatly contribute to an echoing effect. The thunder will sound more boomy and will rumble longer.

Wow, that turned into quite an explanation...

The bottom line of why the thunder was so loud last week: a few positively charged lightning strikes during light to no rain, combined with stratus/overcast conditions helped radiate a joyful noise.

Thanks for reading! George

(BELOW: Gracie dog rolled in the wet grass and clover after I mowed it! She was ready for St. Patrick's Day.)


4 comments:

  1. Very nice explanations! We got some thundersnow in Seattle about a week ago, heard and seen over an unusually wide area. It was borne out of a convergence zone, so the cell that popped the lightning was very isolated and surrounded by clear skies.

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  2. Thanks George we live in Duluth ga and we thought a bomb went off and this has happen quite often this summer for the past few thunder storms. One huge boom then nothing scared the heck out of us

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  3. Tonight my kids and I were awoken to what I thought was the end of the world. The explosion that went off in the sky was so terrifying, never had I witnessed such thunder in all my life.

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