Weekend's 1,000,000 Lightning Strikes vs. Records

UPDATE: Spokesmen for Vaisala said that that the derecho put down 129,000 cloud-to-ground strokes between Chicago and the East Coast June 29th & 30th, but was only tens of miles wide, which isn't much given the large area where it did damage. They say: "On the very big lightning days, there tends to be a long intense squall line, perhaps an MCS, and a lot of activity in the SE states at the same time."

1,196,749 lightning strokes* hit the ground in the U.S. (roughly continental) in the last four days, per Vaisala data (see map below). About half a million of those strikes hit the ground/trees/buildings in the mid-Atlantic. Sounds like an incredible amount of lightning...

So was this weekend's lightning a record?

The data doesn't appear to indicate that it is. Data from Vaisala shows that over 2,200,000* lightning strokes** occurred in the Continental U.S. on July 22-23, 2008 (the largest 2-day total from records between January 2008 and March 2011; I'm working to update this data).

Next question: Is lightning frequency increasing?

It doesn't seem to be, with the limited data set that I have. Because lightning detection is always improving, in theory more lightning can be detected, especially outside the Continental U.S. The graph above shows lightning flashes* from Jan. 1 through April 13 for the last several years.

How much lightning strikes the Earth each year? A lot. This is something I've blogged about before.

Vaisala's worldwide lightning network detected 309,959,570 strokes** in the "summer" (May-Oct) of 2010. Lightning density is plotted on the map below. The U.S. seems to be the lightning country capitol of the world, but NASA says, on average, Africa is the winner.

*563,536 "flash counts" - to get "strokes"** multiply by 2.4. **Technically, a "flash" is one lightning strike which can contain more than one stroke (as discussed in my blog "Lightning Lingo").

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