1. Lightning in Salt Lake and Utah Valleys
Michael Olson
Meteo 5120
Applied Math and Statistics
John Horel

2. Purpose 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.

3. Prior 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 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.

4. Null 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.

5. Procedure 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

6. 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.

7. Data Raw Data Pipe through datafix.c
STN YYMMDD/HHMM SLAT SLON SGNL MULT / / / /
Pipe through datafix.c

9. Strikes on Land Strikes on Water Strikes in Mountains 2004 June July
August
2005

12. Possible Causes of Error
Inaccurate estimations of land/water/mountain locations
Not enough data
Use of latitude & longitude for area instead of Cartesian coordinates.

13. Ways to minimize error or 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)

14. Summary of Results & Conclusion
Average probability of lightning
Over water: / = 11.6%
Over land: / = 48.1%
Over mountain: / = 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.

15. Future 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)?