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World Map of Lightning Activity
Ian writes "NewScientist.com is >reporting that you can now see the lightning activity on the entire planet Earth at one time. The article states, "The NASA map also shows that lightning very rarely occurs at sea and is almost never seen at the Earth's poles." Anyone care to speculate on why that is?"
Why are 'most lightning' and 'least lightning' color schemes the same color?
My estimation is that the extremely low lightning at sea is caused by a general lack of geographic anomalies to disturb airflow.
You'll notice in the map a wide swath of sea to the west of South America which follows the equator and then curves south following the coast. This is approximately the path of the Humbolt and equatorial currents in the South Pacific. Winds and sea currents have a strong influence on each other, and so we may presume that the winds over these strong ocean currents are less turbulent than those over the Polynesians or the Carribean islands. This is consistent with the hypothesis that a lack of turbulence is the cause of low lightning occurrence at sea.
At the poles, the temperature is very low. I'm not sure of the mechanics involved, but I do know that regions with surfaces heated by the sun experience more lightning in general, so we could reasonably presume the opposite about regions of cold surfaces, explaining the lack of lightning at the poles.
I like to play children's songs in minor keys.
"We're all sons of bitches now." --J. Robert Oppenheimer
My preferences can't be that screwed up. Or can they?
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Yeah, I know it's sort of egocentric for we Americans, but you can visit http://www.lightningstorm.com/ls2/gpg/lex1/mapdisp lay_free.jsp?jrunsessionid=1007697160371304360 to see recent lightening activity in the continental US. When things are lively, you can see a lot of really nifty patterns with the fronts.
Anyone know how to build a contraption to detect lightning locally? Is it possible to build something like this in your backyard ?
I would really be interested
Thunderstorms are the thing I miss most about the midwest (I'm from Illinois, live in California), but it looks like the "third coast" (TX, LA, MS, AL, FL) is the place to be in the US for lightning. I think I once read that Lakeland, FL (I believe between Tampa and Orlando) gets the most lightning of any locale in the US. And property is probably really cheap. :-)
Anyone find a high res version of the map in the New Scientist article?
People in Australia with Teletext (Austext, broadcast on Channel 7) can get live info on lightning strikes in Queensland. It even has a map, of sorts. Page 179.
Tell me this isn't cool...
This free 'lightning explorer' shows the most recent strikes in the U.S.
I don't think this one is as impressive.
> The NASA map also shows that lightning very rarely occurs at sea and is almost never seen at the Earth's poles. Anyone care to speculate on why that is?
Far fewer blasphemers in those regions, of course.
Sheesh, evil *and* a jerk. -- Jade
1997-98 EL NIÑO EVENT INCREASED LIGHTNING ACTIVITY
"The 1997-98 El Niño Event and Related Wintertime Lightning Variations in the Southeastern United States" was selected as one of the "Highlight" articles appearing in the February 15 issue of Geophysical Research Letters. The paper describes the increase in lightning activity in the northern Gulf of Mexico Basin in response to the 1997-98 El Niño event. The authors use two data sets to obtain this information. One data set was a 10-year (1989-99) database of U.S. cloud-to-ground lightning activity. The NASA Lightning Imaging Sensor on the Tropical Rainfall Measuring Mission (TRMM) Observatory was also used. The LIS gives the total (in-cloud and cloud-to-ground) lightning activity data recorded from space. Results showed that during 1997-8 a 100-150% increase in lightning days year-to-year and a nearly 200% increase in lightning hours (compared to 1996-7 and 1998-9) in the basin. They attribute these changes to an enhanced synoptic-scale forcing associated with ENSO and a stronger than normal upper-level jet stream. They also find good agreement between most of the recent warm ENSO events and cyclogenesis within the basin.
Cyclogenesis: Process of initiation or intensification of a cyclonic circulation in the atmosphere (source)
ENSO event: ENSO is the term currently used by scientists to describe the full range of the Southern Oscillation that includes both SST increases (a warming) as well as SST decreases (a cooling) when compared to a long-term average. (source)
Maybe it's because lightning wants to be perpendicular to the magnetic field lines of the earth. Therefore, toward the poles, the magnetic field lines are too "curvy" so that the lightning would be forced to go horizontal, resulting in it never being grounded. Who knows though, eh?
It has everything to do with the behavior of static electricity. What were you taught as a kid, should you find yourself in a lightning storm?
Get out in the open. Stay away from trees.
Ever look at a lightning rod?
Static electricity collects at points. The overall lack of geographic features over the ocean pretty much negates most opportunities for static charges to balance themselves between earth and sky, without any points to collect at.
- billn
No lightning at the poles, and very little at sea? Obviously lightning is herbivorous, and tends to roam areas where there are trees to eat.
Nothing to see here. Move along.
Large drops falls through the cloud and collides with smaller drops going up. These collisions transfer charge from the down-going drops to the up-going drops, and thus a larde charge difference between top and bottom of the cloud develops. The large charge in the bottom of the cloud results in the formation of a 'mirror charge' in the ground beneath it and these charges are responsible for the lightning.
Yours Yazeran
Plan: To go to Mars one day with a hammer.
Sufficiently strong convection currents are much more common over land, where the sun can heat ground rapidly.
Another factor is global circulation patterns. Convection causes air to rise at the equator, and to sink at the poles. (actually we get three convection cells, so we also get descending air at 30 degrees latitude, and rising air at 60 degrees). This means that we tend to get high rainfall, storms, and lightning at the equator and at 60 degrees, low rainfall and few storms at 30 degrees and at the poles.
On the other hand, I know from being at sea during any type of storm, you can get some seriously big waves. I imagine that in the middle of the ocean, you'll have wave on the order of 10m high, at least. This seems like enough of a height variation.
I guess there's two reasons I can think of that you wouldn't have strikes over water: first, any charge on the "ground" would tend to disperse more rapidly than it would when you're on land, and second, there's less convection due to the night/day cycle, so the clouds over the ocean rub together a bit less.
I also noticed that the point most hit on the US seemed to be my hometown, New Orleans... I always expected that, baby!
Come on, give it up, that's