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					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 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.
                                                     Data
Raw 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

                         Strikes on Land

                         Strikes on Water

                         Strikes in Mountains




       June   July   August

2005
Month         Lake Density       Land Density      Mountain Density   Lake Strikes        Land Strikes        Mountain Strikes Total Strikes
June 2004                370.07             815.82           1095.5                 181                1029                  876              2086
July 2004                478.43             202.97           217.61                 234                 256                  174               664
June 2005                1069.3             1291.5           1609.6                 523                1629                 1287              3439
July 2005                  132.9            402.76           514.01                  65                 508                  411               984
August 2005              519.32             1400.9           2007.3                 254                1767                 1605              3626
Summer 2004                848.5            1018.8           1313.2                 415                1285                 1050              2750
  Per month              424.25              509.4            656.6               207.5               642.5                  525              1375
Summer 2005              1721.5             3095.2           4130.8                 842                3904                 3303              8049
  Per month              573.83           1031.73           1376.93              280.67             1301.33                 1101              2683
2004 – 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                        Areas (Deg2)              0.4891              1.2613              0.7996            2.5500
              Lowest Densities
    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 (km2 instead of Degrees2)
         Summary of Results &
             Conclusion
●   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 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)?

				
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