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

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.

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 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 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.

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

Procedure (cont...) ● Calculate area (in Degrees 2 ). ● Find Strike Density (# of strikes per unit area). Yields units of Strikes/Degree 2. ● Calculate probabilities of a lightning strike in each of the three regions.

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

Strikes on Land Strikes on Water Strikes in Mountains June July August

Possible 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 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 (km 2 instead of Degrees 2 )

Summary of Results & Conclusion ● Average probability of lightning – Over water:251.4 / = 11.6% – Over land: / = 48.1% – Over mountain:870.6 / = 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 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)?