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?"

Re:Question

[Karma 50]

NASA used different contractors for the top and bottom halves of the lightning scale. These contractors used different units ... with hilarious results.

My Estimation

[Nater]

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.

Re:My Estimation

[Karma 50]

It could also be because they didn't take many measurements at sea and the poles! As evidenced by the fact that these regions are colour-coded grey & white which don't appear on the key.

I'm sure you are right really ... I just thought it amusing that they're drawing conclusions from data that doesn't exist or at least isn't presented in the NS article.

Re:My Estimation

[dstone]

Care to venture a theory as to why there would be gradient patches of BOTH white and grey on that map, then? Maybe grey is where they didn't take measurements, and white is where the really, really didn't take measurements. ;-)

not on main page?

[xah]

Why isn't this on the main page?

My preferences can't be that screwed up. Or can they?

Re:not on main page?

[xah]

Argh. It's true. I didn't have the "Science" slashbox checked.

If you are more interested in just the US...

[CheshireCatCO]

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 [lightningstorm.com] 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.

Re:Anyone know how to build a lightning detector ?

[TinWeasle]

Yes! Connect a 20 foot iron pole to a ground loop. Stand in a bucket of water holding the iron pole. This is guaranteed to let you know when there is lightning in the area.

Re:Anyone know how to build a lightning detector ?

[FlashBoltzmann]

One really crude way is to just turn on an AM radio during a storm and listen for the brief pops caused by lightning. One page you should look at is here:

http://www.altair.org/natradio.htm

It talks about the different types of EM radiation created by lightning. I think if you wind some wire around an iron core, connect the wires to a battery and transistor to boost the power and connect it to the speaker you should get some interesting pops during lightning. If you are familiar with band pass filters in electronics you could probably filter it so that you only pick up the frequencies you hear lightning on (which is a very broad range). It isn't hard to hear it. Now lightning prediction...I can't vouch for that.

Re:Anyone know how to build a lightning detector ?

[t]

My current theory for locating lightning is to use an unshielded mic to pick up the static bursts from lightning (or the AM thing from FlashBoltzmann which I've never tried). Then assuming that you have several geographically distributed friends with known GPS coordinates and decently synced clocks, you should be able to do some poor-mans triangulation by comparing stats.

btw, this is a really cool site Wavelet Compression of Lightning Signatures [lanl.gov].

t.

Re:Anyone know how to build a lightning detector ?

[Yazeran]

Well you could only use this technique if you use the sonic signals to triangulate from. Unless you have some extremly accurate clocks, then you would not be able to detect any difference in the arrival-time between the different listening stations, if you try to use the electromagnetic signal from the lightning.

Remember, than electromagnetic radiation travels with the speed of light! The time it takes for the electromagnetic signal from a lightning strike 10 km away to travel to the receiver is only 33 micro seconds. if you use the sonic signal, however, you would be able to do the triangulation fairly easily with relatively cheap watches. Your only concern would be that you and your friends should be certain that you measure the arrival time for the same lightning strike.

Yours Yazeran

Plan: To go to Mars one day with a hammer.

Re:Anyone know how to build a lightning detector ?

[t]

sorry, in re-reading my post I realize I left out some crucial details in my terseness. When you use an unshielded mic to record audio out the window, the EM burst from the lightning sounds like a little static pop. This would be analagous to seeing the flash from the lightning. Then a bit later you'll have the thunder on the audio recording. The static burst is easier to detect using methods similar to the site I linked. THen you can use a similar scheme like you would counting seconds between flash and thunder to estimate distance.

As long as you're not in a raging lightning storm, you can correlate lightning strikes recorded at different computers by using a large error tolerance. e.g. the EM burst from this strike was recorded on three different computers within a span of 15 seconds. We can assume that this was the same event if the lightning was spaced several minutes apart during the storm.

The time for the EM burst to travel is considered to be zero for ease of computation. Not to mention the impossiblity of keeping things accurate for that to even be useful.

Also my initial test showed EM bursts that were o.w. undetectable which is pretty cool. Maybe the first step is an early detection system for lightning storms.

t.

Re:Anyone know how to build a lightning detector ?

[sphealey]

Remember, than electromagnetic radiation travels with the speed of light! The time it takes for the electromagnetic signal from a lightning strike 10 km away to travel to the receiver is only 33 micro seconds. if you use the sonic signal, however, you would be able to do the triangulation fairly easily with relatively cheap watches. Your only concern would be that you and your friends should be certain that you measure the arrival time for the same lightning strike.

Interesting point. So how does the National Lightning Detection Network [lightningstorm.com] do it? GPS-based timing signals? And if one were to try to recreate this, with distances of, say, 250 km between low-cost detectors [boltek.com], would the clocking available on standards PC's be sufficient, or would special-purpose hardware be needed?

sPh

Re:Anyone know how to build a lightning detector ?

[sphealey]

Try Boltek [boltek.com] as a starting point; there are other, similar systems out there as well.

sPh

Neat

[mlinksva]

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?

Re:Neat

[z19752002]

I used to live in Sarasota FL ("Peter Pan Kindernook" anyone?) and also Bartow FL [mapquest.com] (Floral Avenue Elementary anyone?) and it is true that central Florida is the lightning capital of the nation [archbold-station.org]. The weather can be genuinely awe-inspiring.

You are right, property there is reasonably priced [realtor.com].

Re:Neat

[sphealey]

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.

Actually, if you Google on National Lightning Detection Network, you will find some information on this topic. When lighting researchers shifted from "thunder days" (as reported by weather station observers using the Mark I Human Ear) to RF-based detection systems, they discovered that the central Midwest had a lightning frequency as high as Florida. Just not as many people around to report it!

sPh

QLD, Australia and Teletext

[Kris_J]

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.

Naturally.

[Black Parrot]

> 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.

No lightning at poles....

[jokrswild]

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?

Why lightning strikes are rare over the ocean/pole

[billn]

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.

Re:Why lightning strikes are rare over the ocean/p

[Debillitatus]

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.

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!

One theory

[Wolfger]

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.

Re:One theory

[Yottabyte84]

What about the middle of africa?

No lightning at the poles.

[Yazeran]

The reason for no lightning at the poles, is thet in order for a cloud to be electrically charged it has to be composed of droplets of liquid water. The current theory about how clouds charge is by colisions of drops in the cloud.
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.

Re:No lightning at the poles.

[p4k]

I think this is the wrong way round, you need actually need ice crystals to generate static charge. Mountain ranges where it is too cold for there to be any possibility of liquid water still get thunderstorms (in fact mountains tend to get very frequent thunderstorms). Also, even in warm areas most of a thunderstorm is at high enough altitude to be ice rather than water.

The reason why there is no lightning at the poles is that there is almost no precipition or convection currents - IIRC the poles get less precipitation than the Sahara desert!

Prerequisites for lightning

[p4k]

You are likely to get a sufficient buildup of charge for lightning to occur when you have strong turbulence and ice crystals present, which requires strong convection currents at high altitude.

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.