Lightning in Salt LakeLightning in Salt Lakeand Utah Valleysand Utah Valleys

Michael OlsonMichael Olson

Meteo 5120Meteo 5120

Applied Math and StatisticsApplied Math and Statistics

John HorelJohn Horel

PurposePurpose● To determine where lightning has more potential

to strike– Over water– Over land– Over mountain

● Increase understanding of lightning “danger zones.”

● Increase understanding of when lightning is a possibility – increase forecasting ability.

Prior ResearchPrior Research● “Where Lightning Strikes,” an article from NASA's magazine

Science at NASA, Dec. 5, 2001, Internet posting:

– Research on locations where lightning occurs more frequently. Lightning avoids the oceans and the poles, but is attracted to land.

– The mapping of lightning activity is done by satellite.● “A Bolt out of the Blue” from Scientific American, May 2005

issue.

– Experiments done in Florida relating lightning and X-rays. Florida chosen because lightning occurs very frequently there without notice, or “Out of the Blue.”

● Other research done that doesn't apply to results.

Null HypothesisNull Hypothesis● Due to the higher conductivity of the salty air

around the Great Salt Lake, a potential for a lightning strike is greater.

● Due to the lower pressure and dryer air of the higher altitudes, lightning strikes are more rare in the mountains.

ProcedureProcedure● Obtain and clean data so it is readable into

Matlab● From data set, select only the strikes in the Salt

Lake and Utah Valleys (40° N to 41°45' N and 111°30' W to 113°15' W)

● Separate data into regions of land, water, or mountain

● Produce Plots

Procedure (cont...)Procedure (cont...)● Calculate area (in Degrees2).● Find Strike Density (# of strikes per unit area).

Yields units of Strikes/Degree2.● Calculate probabilities of a lightning strike in

each of the three regions.

DataDataRaw Data STN YYMMDD/HHMM SLAT SLON SGNL MULT

+ 050601/2100 23.96 -79.65 190.00 1.00

- 050601/2100 27.26 -87.50 -130.00 1.00

- 050601/2100 43.96 -117.32 -30.00 1.00

- 050601/2100 27.96 -85.16 -150.00 8.00

Pipe through datafix.c 0506012100 23.96 -79.65 190.00 1.00

0506012100 27.26 -87.50 -130.00 1.00

0506012100 43.96 -117.32 -30.00 1.00

0506012100 27.96 -85.16 -150.00 8.00

2004

2005

Strikes on Land

Strikes on Water

Strikes in Mountains

June July August

Month Lake Density Land Density Mountain Density Lake Strikes Land Strikes Mountain Strikes Total StrikesJune 2004 370.07 815.82 1095.5 181 1029 876 2086July 2004 478.43 202.97 217.61 234 256 174 664June 2005 1069.3 1291.5 1609.6 523 1629 1287 3439July 2005 132.9 402.76 514.01 65 508 411 984August 2005 519.32 1400.9 2007.3 254 1767 1605 3626Summer 2004 848.5 1018.8 1313.2 415 1285 1050 2750 Per month 424.25 509.4 656.6 207.5 642.5 525 1375Summer 2005 1721.5 3095.2 4130.8 842 3904 3303 8049 Per month 573.83 1031.73 1376.93 280.67 1301.33 1101 26832004 – 2005 2570 4114 5444 1257 5189 4353 10799 Per month 514 822.8 1088.8 251.74 1037.8 870.6 2159.8

Highest Densities 0.4891 1.2613 0.7996 2.5500Lowest Densities

Areas (Deg2)

Possible Causes of ErrorPossible Causes of Error● Inaccurate estimations of land/water/mountain

locations● Not enough data● Use of latitude & longitude for area instead of

Cartesian coordinates.

Ways to minimize errorWays to minimize erroror obtain clearer resultsor obtain clearer results

● More data● Compare month to month series analysis

(compare all Junes to each other, all Julys to each other, etc.)

● Compare with other bodies of water (salt water vs. fresh water, large body vs. small body, etc.)

● Better area units (km2 instead of Degrees2)

Summary of Results & Summary of Results & ConclusionConclusion

● Average probability of lightning

– Over water: 251.4 / 2159.8 = 11.6%– Over land: 1037.8 / 2159.8 = 48.1%– Over mountain: 870.6 / 2159.8 = 40.3%

● Water is not more conducive to lightning, even if the air above contains conductive ions like Na+ and Cl-.

● The possibility of a lightning strike is highest over land using probabilities, but highest over mountain ranges using strike densities.

Future ResearchFuture Research● Why is July so sparsely populated with lightning

strikes?● What are the conditions that enhance the

probability of lightning?● What makes some area of the world (such as

Florida) ideal for lightning strikes and others not (like the Pacific Islands)?