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.)

Wednesday, March 14, 2012

Skywatching: Jupiter and Venus. Mars too.

(ABOVE: I stole this graphic from

"Are those UFOs?!" asked an alarmed viewer who called KJRH. You might have also wondered about the so-called "bright lights" in the sky.

Tonight, take a look at the western sky. You will see two bright white dots near each other. Those two dots are Jupiter and Venus, and you will know they are planets because they don't blink or sparkle like stars do.

You will see Jupiter on the left and Venus on the right. Jupiter will appear slightly dimmer and lower in the sky compared to Venus.

Check them out tonight! Between 7-9pm is a great time for viewing. Look due west and up at just under a 45 degree angle-- you can't miss them!

As far as the weather, you might have some clouds in the way, but try to enjoy the planets while you can. Jupiter will disappear from your view toward the end of March as it sinks lower in the sky.

Also, while you are out, check out Mars too. Look nearly due east and lower in the sky. Mars will appear as a dim, smallish orange dot in the eastern sky above the horizon.

Take advantage of the Spring-like weather and enjoy our universe!

(BELOW: I took this pic last night of Jupiter and Venus. Of course cell phones don't take great pics at night, but it gives you an idea of what to expect. The planets will appear brighter to your own eyes.)

Friday, March 9, 2012

Graupel-- huh?!

(March 8, 2012. Photo courtesy: Marcie M. from Keys, OK. Picture shows a hybrid of ice. This could be considered as graupel...maybe...)

"It's hailing! Wait, I think it's sleet. Uhm, this can’t be snow, uhm, it's uhm…"

If you muttered this to yourself yesterday, you aren't alone!

Yesterday during the cold rain you may have seen graupel (a word the spell checker doesn't even like!) for the first time in your life-- so what is it?

Graupel could be considered part rain, sleet and snow, and it's rare in Oklahoma. In layman's terms, it's a bit of an ice hybrid.

Graupel forms during cold precipitation.

Cold, above ground temperatures cause the precipitation to begin as snow, remaining mostly frozen from cloud level to near the surface. The snow gradually melts above the ground while rain or sleet attempt to freeze to the melting snow.

The rain exists in what's called a "supercooled" state-- water in a liquid form below 32 degrees as it adheres to what's left of the snow. (Supercooled water/moisture is common in clouds.)

You can end up with a compact, smallish icy/snow pellet. It's hard to nail down the precipitation type from viewer pictures alone, and it's debatable whether you call it graupel, sleet, and/or ice pellets. Melting doesn't help identifying the precip type either.

Across Oklahoma, nearly all forms of precipitation fell yesterday in the cold weather: a few flurries were reported west, sleet covering the road in eastern Oklahoma, some small hail fell during "pulse" type storms during the morning. A few reports of the icy slush/maybe graupel came in as temperatures dropped.

Enjoy the pictures on this page... George

(Below: The Wilson family in South Tulsa sent in these pictures of the melting mess. It's difficult to tell whether it's sleet, small hail, ice/snow pellets or graupel.)