scholarly journals on the prevention of lighting

1969 ◽  
Vol 50 (7) ◽  
pp. 514-521 ◽  
Author(s):  
C. D. Stow
Keyword(s):  
United States ◽  
Forest Fires ◽  
Western United States ◽  
Agricultural Crops ◽  
Loss Of Life ◽  
The World ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning ◽  
Recreational Resources

The destructive nature of cloud-to-ground lightning strokes is well known. Loss of life and damage to buildings and other man-made structures may to a large extent be prevented by the judicial use of lightning conductors and screens but no comparable protection may be offered to expanses of agricultural crops or forests. According to Fuquay (1967) lightning is the greatest single cause of forest fires in the western United States: during the period 1946–1962, 140,000 such fires occurred causing severe losses of timber, wildlife, watershed, and recreational resources. Comparable losses occur regularly in other parts of the world. The only solution is the suppression or modification of cloud-to-ground lightning discharges. Methods of suppression are described, some of which may turn out to be practical ways of achieving this aim.

scholarly journals First ground-based observations of sprites over southern Africa

2018 ◽  
Vol 114 (9/10) ◽  
Author(s):  
Stanislaus Nnadih ◽  
Mike Kosch ◽  
Peter Martinez ◽  
Jozsef Bor
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Dielectric Breakdown ◽  
Electrical Discharges ◽  
Lightning Strikes ◽  
The World ◽  
Lightning Discharges ◽  
Northern Cape ◽  
Cloud To Ground Lightning ◽  
Peak Value

Sprites are the optical signatures of electrical discharges in the mesosphere triggered by large lightning strikes associated with thunderstorms. Since their discovery in the late 1980s, sprites have been observed extensively around the world, although very few observations of sprites from Africa have been documented in the literature. In this paper, we report the first ground-based recorded observations of sprites from South Africa. In 2 out of the 22 nights of observations (11 January and 2 February 2016), about 100 sprite elements were recorded from Sutherland in the Northern Cape, comprising different morphologies (carrot (55%), carrot/column (11%), unclassified (21%), column (13%)). The sprites were triggered by positive cloud-to-ground lightning strikes, which had an average peak value of ~74 kA and were observed at distances from ~400 km to 800 km. The estimated charge moment change of the lightning discharges associated with these events was in agreement with the threshold for dielectric breakdown of the mesosphere and correlates well with the observed sprite brightness.

A Review of Positive and Bipolar Lightning Discharges

2003 ◽  
Vol 84 (6) ◽  
pp. 767-776 ◽  
Author(s):  
V. A. Rakov
Keyword(s):  
Forest Fires ◽  
Return Stroke ◽  
Winter Storms ◽  
Convective Systems ◽  
Lightning Channel ◽  
Different Types ◽  
Mesoscale Convective ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning ◽  
Positive Return

Characteristics of lightning discharges that transport either positive charge or both positive and negative charges to the ground are reviewed. These are termed positive and bipolar lightning discharges, respectively. Different types of positive and bipolar lightning are discussed. Although positive lightning discharges account for 10% or less of global cloud-to-ground lightning activity, there are five situations that appear to be conducive to the more frequent occurrence of positive lightning. These situations include 1) the dissipating stage of an individual thunderstorm, 2) winter thunderstorms, 3) trailing stratiform regions of mesoscale convective systems, 4) some severe storms, and 5) thunderclouds formed over forest fires or contaminated by smoke. The highest directly measured lightning currents (near 300 kA) and the largest charge transfers (hundreds of coulombs or more) are thought to be associated with positive lightning. Two types of impulsive positive current waveforms have been observed. One type is characterized by rise times of the order of 10 μs, comparable to those for first strokes in negative lightning, and the other type is characterized by considerably longer rise times, up to hundreds of microseconds. The latter waveforms are apparently associated with very long, 1–2 km, upward negative connecting leaders. The positive return-stroke speed is of the order of 108 m s−1. Positive flashes are usually composed of a single stroke. Positive return strokes often appear to be preceded by significant in-cloud discharge activity, then followed by continuing currents, and involve long horizontal channels. In contrast to negative leaders, which are always optically stepped when they propagate in virgin air, positive leaders seem to be able to move either continuously or in a stepped fashion. The reported percentage of bipolar flashes in summer storms ranges from 6% to 14% and from 5% to 33% in winter storms. Bipolar lightning discharges are usually initiated by upward leaders from tall objects. It appears that positive and negative charge sources in the cloud are tapped by different upward branches of the bipolar-lightning channel.

Influence of the Madden–Julian Oscillation on Summertime Cloud-to-Ground Lightning Activity over the Continental United States

2009 ◽  
Vol 137 (10) ◽  
pp. 3596-3601 ◽  
Author(s):  
John T. Abatzoglou ◽  
Timothy J. Brown
Keyword(s):  
United States ◽  
Great Basin ◽  
Lightning Activity ◽  
Western United States ◽  
Madden Julian Oscillation ◽  
Lightning Strikes ◽  
Northern Rocky Mountains ◽  
Seasonally Dry ◽  
Desert Southwest ◽  
Cloud To Ground Lightning

Abstract Summertime cloud-to-ground lightning strikes are responsible for the majority of wildfire ignitions across vast sections of the seasonally dry western United States. In this study, a strong connection between active phases of the Madden–Julian oscillation (MJO) and regional summertime lightning activity was found across the interior western United States. This intraseasonal mode of lightning activity emanates northward from the desert Southwest across the Great Basin and into the northern Rocky Mountains. The MJO is shown to provide favorable conditions for the northward propagation of widespread lightning activity through the amplification of the upper-level ridge over the western United States and the development of midtropospheric instability. Given the relative predictability of the MJO with long lead times, results allude to the potential for intraseasonal predictability of lightning activity and proactive fire management planning.

W. D. Matthew, Fossil Vertebrates and Geological Time

1989 ◽  
Vol 8 (2) ◽  
pp. 159-166
Author(s):  
Ronald Rainger
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Time Scale ◽  
Western United States ◽  
Geological Time ◽  
Geological Time Scale ◽  
Vertebrate Fauna ◽  
Early Twentieth Century ◽  
The World

William Diller Matthew (1871-1930) was one of the leading vertebrate paleontologists of the early twentieth century. His taxonomic and phylogenetic researches significantly changed the understanding of evolution of many families and orders of mammals. In addition, Matthew was much concerned with geological questions. His biostratigraphic studies considerably refined understanding of the localities and ranges of Tertiary vertebrate fauna in the western United States, and he extended those interpretations to define correlations between American stratigraphic units and those in other areas of the world. On the basis of that work, Matthew made notable contributions to the understanding and improvement of the geological time scale.

scholarly journals Recent Tree Mortality in the Western United States from Bark Beetles and Forest Fires

2016 ◽  
Vol 62 (2) ◽  
pp. 141-153 ◽  
Author(s):  
Jeffrey A. Hicke ◽  
Arjan J.H. Meddens ◽  
Crystal A. Kolden
Keyword(s):  
United States ◽  
Forest Fires ◽  
Bark Beetles ◽  
Tree Mortality ◽  
Western United States

scholarly journals Biomass burning contribution to black carbon in the Western United States Mountain Ranges

2011 ◽  
Vol 11 (21) ◽  
pp. 11253-11266 ◽  
Author(s):  
Y. H. Mao ◽  
Q. B. Li ◽  
L. Zhang ◽  
Y. Chen ◽  
J. T. Randerson ◽  
...  
Keyword(s):  
United States ◽  
Black Carbon ◽  
Biomass Burning ◽  
Forest Fires ◽  
Transport Model ◽  
Reanalysis Data ◽  
Western United States ◽  
Fire Season ◽  
Carbonaceous Aerosols ◽  
Mountain Ranges

Abstract. Forest fires are an important source to carbonaceous aerosols in the Western United States (WUS). We quantify the relative contribution of biomass burning to black carbon (BC) in the WUS mountain ranges by analyzing surface BC observations for 2006 from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network using the GEOS-Chem global chemical transport model. Observed surface BC concentrations show broad maxima during late June to early November. Enhanced potassium concentrations and potassium/sulfur ratios observed during the high-BC events indicate a dominant biomass burning influence during the peak fire season. Model surface BC reproduces the observed day-to day and synoptic variabilities in regions downwind of but near urban centers. Major discrepancies are found at elevated mountainous sites during the July-October fire season when simulated BC concentrations are biased low by a factor of two. We attribute these low biases largely to the underestimated (by more than a factor of two) and temporally misplaced biomass burning emissions of BC in the model. Additionally, we find that the biomass burning contribution to surface BC concentrations in the USA likely was underestimated in a previous study using GEOS-Chem (Park et al., 2003), because of the unusually low planetary boundary layer (PBL) heights in the GEOS-3 meteorological reanalysis data used to drive the model. PBL heights from GEOS-4 and GEOS-5 reanalysis data are comparable to those from the North American Regional Reanalysis (NARR). Model simulations show slightly improved agreements with the observations when driven by GEOS-5 reanalysis data, but model results are still biased low. The use of biomass burning emissions with diurnal cycle, synoptic variability, and plume injection has relatively small impact on the simulated surface BC concentrations in the WUS.

scholarly journals Effects of Climate Change on Natural-Caused Fire Activity in Western U.S. National Forests

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 981
Author(s):  
Hadi Heidari ◽  
Mazdak Arabi ◽  
Travis Warziniack
Keyword(s):  
Climate Change ◽  
United States ◽  
Forest Fire ◽  
Forest Fires ◽  
Western United States ◽  
National Forests ◽  
Climate Change Scenarios ◽  
Negative Consequences ◽  
Fire Activity ◽  
The Future

Climate change, with warming temperatures and shifting precipitation patterns, may increase natural-caused forest fire activity. Increasing natural-caused fires throughout western United States national forests could place people, property, and infrastructure at risk in the future. We used the fine K nearest neighbor (KNN) method coupled with the downscaled Multivariate Adaptive Constructed Analogs (MACA) climate dataset to estimate changes in the rate of natural-caused fires in western United States national forests. We projected changes in the rate of minor and major forest fires from historical (1986–2015) to future (2070–2099) conditions to characterize fire-prone national forests under a range of climate change scenarios. The results indicate that climate change can add to the occurrence of forest fires in western United States national forests, particularly in Rocky Mountain, Pacific Southwest, and Southwestern United States Forest Service regions. Although summer months are projected to have the highest rate of natural-caused forest fire activity in the future, the rate of natural-caused forest fires is likely to increase from August to December in the future compared to the historical conditions. Improved understanding of altered forest fire regimes can help forest managers to better understand the potential effects of climate change on future fire activity and implement actions to attenuate possible negative consequences.

Distribution of Yellow Starthistle (Centaurea solstitialis) and Russian Knapweed (Centaurea repens)

Weed Science ◽  
1985 ◽  
Vol 33 (3) ◽  
pp. 315-327 ◽  
Author(s):  
Donald M. Maddox ◽  
Aubrey Mayfield ◽  
Noah H. Poritz
Keyword(s):  
United States ◽  
The United States ◽  
Economic Importance ◽  
Western United States ◽  
Centaurea Solstitialis ◽  
Yellow Starthistle ◽  
Russian Knapweed ◽  
Centaurea Repens ◽  
The World ◽  
Made In

The world distributions of yellow starthistle (Centaurea solstitialis L. ♯ CENSO) and Russian knapweed (Centaurea repens L. ♯ CENRE) are mapped based on information from world regional floras. A survey of weed specialists and herbaria was made in the United States, and the extent of the infestations and economic importance of these weeds was determined for the 48 contiguous states. Yellow starthistle currently occurs in 209 counties in 23 states and has apparently increased in abundance since 1970. Russian knapweed was reported in 412 counties in 21 states and does not seem to be spreading. Both of these weedy plant species are of greater economic importance in the western United States than in the east.

scholarly journals Model-Generated Predictions of Dry Thunderstorm Potential

2007 ◽  
Vol 46 (5) ◽  
pp. 605-614 ◽  
Author(s):  
Miriam L. Rorig ◽  
Steven J. McKay ◽  
Sue A. Ferguson ◽  
Paul Werth
Keyword(s):  
United States ◽  
Mesoscale Model ◽  
Western United States ◽  
State University ◽  
Lightning Strikes ◽  
Convective Storms ◽  
Interagency Coordination ◽  
Fifth Generation ◽  
Cloud To Ground Lightning ◽  
Fire Ignitions

Abstract Dry thunderstorms (those that occur without significant rainfall at the ground) are common in the interior western United States. Moisture drawn into the area from the Gulfs of Mexico and California is sufficient to form high-based thunderstorms. Rain often evaporates before reaching the ground, and cloud-to-ground lightning generated by these storms strikes dry fuels. Fire weather forecasters at the National Weather Service and the National Interagency Coordination Center try to anticipate days with widespread dry thunderstorms because they result in multiple fire ignitions, often in remote areas. The probability of the occurrence of dry thunderstorms that produce fire-igniting lightning strikes was found to be greater on days with high instability and a deficit of moisture at low levels of the atmosphere. Based on these upper-air variables, an algorithm was developed to estimate the potential of dry lightning (lightning that strikes the ground with little or no rainfall at the surface) when convective storms are expected. In the current study, this algorithm has been applied throughout the western United States, with modeled meteorological variables rather than the observed soundings that have previously been used, to develop a predictive scheme for estimating the risk of dry thunderstorms. Predictions of the risk of dry thunderstorms were generated from real-time forecasts using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) for the summers of 2004 and 2005. During that period, 240 large lightning-caused fires were ignited in the model domain. Of those fires, 40% occurred where the probability of dry lightning was predicted to be equal to or greater than 90% and 58% occurred where the probability was 75% or greater.

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