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Section 6.5.3

Results Summary for NLSI Research Program on Comparative Behavior of Air Terminals

1. The site work was completed in early August. About 50% of the lightning season was over by the time set-up was finished.

2. No strikes to any of the eighty air terminals were recorded during the 1999 season. High winds, in excess of 70 mph, were responsible for knocking down some platforms. All platforms were re-fastened at four points, instead of the original two points.

3. A National Geographic film crew from London UK visited the site. It will be mentioned in an upcoming program on global weather safety.

4. Modifications to the experiment are scheduled for next year. They include:

a. Increase air terminal tip spacing from the present one foot to five feet by changing the mounting configuration.
b. Installing two amp fuses in place of the twenty amp fuses used in 1999.
c. Installing current measuring devices to be provided by US West.

5. A HALOS Facility Site Analysis provided by Global Atmospherics has been posted to the NLSI WWW site. Flash density is GAI-reported as 2-4 flashes per 3 sq. km./yr. Measurement by observation indicates that figure is low. See GAI data at Chapter 6, NLSI Research.


Year 2001 Update at NLSI Research Project

Putting Up Aluminum Rods at the Site


Here is the latest news at the end of the 2001 lightning season:

  1. Several suspected strikes to rods were examined, but could not be confirmed by an independent source. (We sent the questionable rod tips to Charles Moore of New Mexico Tech, who is the originator of the "preferential rod tip geometry" experiment at his Langmuir Lab NM site.)

  2. In Sept. 2001, we changed out all 80 steel rods for aluminum rods. Aluminum is about 25% softer than steel so these new rods have a much better likelihood of showing clear evidence of pitting and arcing from the effects of lightning. The new rods are at the HALOS site (about 12,000 ft. elev., and located about 7 miles N. of Nederland CO on Niwot Ridge).

    See also the Univ. Colorado WWW site at:

  3. We plan to continue the experiment for 3-4 more years.

    1. General lightning flash density was some 50% below normal for the 1999 and 2000 seasons. It was about 125% of normal during 2001.

      Year 2002 Update at NLSI Research Project

      No strikes to any of the 80 rods were observed, although overall lightning flash activity was higher than in past years. We will continue the experiment into the 2003 season.

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