Download or read book Thunderstorm Characteristics of a Cloud to Ground Lightning at the NASA Kennedy Space Center Florida A Study of Lightning Initiation Signatures as Indicated by Doppler Radar written by Michael Gremillion and published by . This book was released on 1998 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: A summary of lightning characteristics was developed for the NASA Kennedy Space Center (KSC). From a 1989-1996 data set, the spatial patterns, temporal patterns, and first stroke mean peak current were analyzed. Forty five thunderstorms were chosen due to their isolated development over KSC. Forty of the storms representing summer (May through September) airmass, thunderstorms and five storms representing winter were examined for their storm initiation characteristics. Radar reflectivity echoes at the -10, -15, and -20 deg C temperature heights were associated with cloud-to-ground (CG) lightning strike locations from the National Lightning Detection Network. A distinct region of high ground flash densities can be seen over land matching the topography of the KSC coastline. A maximum of values was observed during the summer months for both negative and positive flashes. The absolute magnitude of negative peak currents was found to be higher than positive peak currents in Florida. Although thunderstorms can occur at any time during the day, the diurnal distribution of lightning flashes showed that the afternoon (2000-2200 UTC) was the time of maximum lightning activity. From a time history of radar echoes, it was found that the 30 dBZ echo detected at the -15 deg C temperature height is the best indicator of the beginning of CG lightning activity. The observed median lag time between this lightning initiation signature and the beginning of CG lightning flashes was 15.5 minutes. Other lightning initiation signatures were also examined at all three temperature heights and did not yield as successful results.

Download or read book Thunderstorm Characteristics of Cloud to ground Lightning at the Kennedy Space Center Florida written by Michael Shane Gremillion and published by . This book was released on 1998 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Conference on Probability and Statistics in Atmospheric Sciences written by and published by . This book was released on with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Conference on Radar Meteorology written by and published by . This book was released on 1999 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of the Characteristics of Thunderstorm Cessation at the NASA Kennedy Space Center written by Michael Shawn Hinson and published by . This book was released on 1997-07-01 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lightning summary was developed for a 100x100 kilometer area centered at the NASA Kennedy Space Center. Spatial and temporal patterns, and first stroke peak currents were analyzed from 1986-1995. Three thunderstorms were chosen due to their proximity to the Kennedy Space Center (KSC) and examined for their end of storm characteristics. Radar echoes at the -10 deg C and -20 deg C temperature heights were associated with cloud to ground (CG) lightning strike locations from the National Lightning Detection Network. Electric fields were also examined during the same time frame for any correlations. A pattern was observed for the spatial distribution of CG lightning. An inland maximum in ground flash density was observed during the summer months for both negative and positive flashes. The summer months had the lowest percentage positive flashes (2.5%) while the maximum value occurred during the winter (11.4%). Although thunderstorms can occur at any time during the day, the diurnal distribution of lightning flashes showed that the afternoon (2000 UTC) was the time of maximum lightning activity. From a time history of radar echoes, it was found that a 45 dBZ echo, last detected at the -10 deg C temperature height, may be a good indicator of the end of lightning activity. The observed lag times between this lightning termination signature and the end of all CG lightning flashes was 30 min for all three thunderstorms.

Download or read book Conference on Applied Climatology written by and published by . This book was released on with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 91 0248 91 0284 written by and published by . This book was released on 1991 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determining the Characteristics of Anvil and Thunderstorm Lightning for Use in the Lightning Launch Control Criteria at Cape Canaveral Air Force Station and Kennedy Space Center written by Zachary Tamurian and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The 45th Weather Squadron (45WS) provides weather support to America's space program at Florida's Cape Canaveral Air Force Station (CCAFS), Kennedy Space Center (KSC), and Patrick Air Force Base (PAFB). Since CCAFS/KSC lies within Florida's "Lightning Alley", summer thunderstorms and associated hazards are a special concern for space launches and all other outdoor activities at CCAFS/KSC. Therefore, the 45WS has developed the Lightning Launch Commit Criteria (LLCC) to help minimize hazards from lightning (both naturally occurring and triggered) and vehicle electrification during the ascent phase of launch. This study has documented the spatial distributions and time evolution of total lightning and radar reflectivity in and around thunderstorms, attached anvil clouds, and detached anvil clouds near CCAFS/KSC on 30 active lightning days between 2008-11. Our goal was to determine if some of the current LLCC thresholds are too restrictive and represent missed launch opportunities, or not restrictive enough and represent a safety risk. CG flashes originating inside the convective core or its anvil can strike the ground away from the cloud edge. Since these side flashes often strike the ground under clear skies, they commonly are referred to as "bolts from the blue". Our results indicate that the vast majority of CG flashes (~94%) strike the ground = 5 n mi from cloud edge (0 dBZ) whereas 73% of CG flashes are = 3 n mi outside 0 dBZ. Three positive bolts from the blue were documented, and all came from the same storm on 29 May 2009. One of the positive flashes propagated 8.91 n mi from cloud edge. Anvil initiated lightning can distribute charge after detachment, but only for a short period. We analyzed 100 anvils within 100 km of KSC; 895 IC flashes in the anvil were initiated in the core of the storms. The first core initiated flash of each anvil typically propagated = 10 n mi. Cellular thunderstorms produce the greatest percentage of total lightning (~84%) in our dataset, but average flash distances from the core are greatest in attached anvils (~4.98 n mi). To our knowledge this is the first study to quantify the distances that lightning can extend beyond the edge of clouds. We believe the results of this research should be considered before making additional changes to the LLCC.

Download or read book Preprints Radar Meteorology Conference written by and published by . This book was released on 1991 with total page 1068 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book World Conference on Radio Meteorology Incorporating the Eleventh Weather Radar Conference written by and published by . This book was released on with total page 1066 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lightning and the space program written by and published by . This book was released on 2004 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characteristics of Decaying Storms During Lightning Cessation at Kennedy Space Center and Cape Canaveral Air Force Station written by Holly Alison Anderson and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Although most storms experienced gradually decaying flash rates until cessation, two other cessation behaviors also were observed, making flash activity an unreliable indicator of cessation. Trends in composite reflectivity, reflectivity at three temperatures crucial to storm electrification (i.e., 0°C, -10°C, -20°C), storm thickness of 30 dBZ above -10°C, and vertical gradients of reflectivity were analyzed for 20 storms during the 8 min period prior to cessation to determine if any indicated imminent cessation. Results showed substantial variability in the decaying storms. Although these parameters decreased in most storms during the 8 min period, some increased. Distributions of the parameters at the last flash also were considered, but no clearly preferred value was evident at the last flash. Neither the inversion of lightning initiation criteria (e.g., 40 dBZ at -10°C) nor the descent of 45 dBZ below -10°C were found to be a useful indicator of cessation. Previously-documented lightning "bubbles" of LDAR sources were observed and were consistent with pulses in the intensifying updrafts. The last lightning "bubble" signatures were found to precede lightning cessation by ~35 min.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1993 with total page 1146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Studies of Thunderstorm Electrification written by Donald R. Fitzgerald and published by . This book was released on 1976 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Airborne electric field sensing and computing systems have been developed and flown on C-130, F-100F, RF4C, and U-2 aircraft for studies of shower, cloud, and thunderstorm charge centers. Examples are given of the proper separation of field components and aircraft charge during thunderstorm penetrations and during direct lightning strikes to the test aircraft. Techniques have been employed for roll compensation of the aircraft-fixed field components so that real-time vector displays indicating the centroid of near-by charge concentrations are available for use in avoidance of probable lightning areas, or for use in selecting them to maximize the probability of a strike to test aircraft during lightning-aircraft interaction studies. The development of the storm electrical structure is directly related to details of the cloud water and ice distribution linked through the thermal and draft structure in the storm. Major features of the internal electrical pattern are often seen in data taken above, alongside, or at the surface. However, in accordance with electrostatic field theory, many of the fine structural details found within the storm are suppressed outside. The major vertical component field pattern is found to be one that could be produced by simple tilted dipolar charge structures. Depending on the physical conditions in different regions of the storm, the upper excess charge of the dipole may be either positive as generally reported from surface observations of the field, or it may be negative, as found in a number of the U-2 storm overflights accomplished in this project. (Author).

Download or read book Thunderstorm Lightning and Radar Characteristics written by Scott Michael Steiger and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Total lightning mapping, along with radar and NLDN cloud-to-ground lightning data, can be used to diagnose the severity of a storm. Analysis of the 13 October 2001supercell event (Dallas-Fort Worth, Texas), some supercells of which were tornadic, shows that LDAR II lightning source heights (quartile, median, and 95th percentile heights) increased as the storms intensified. Most of the total lightning occurred where reflectivity cores extended upwards and within regions of reflectivity gradient rather than in reflectivity cores. A total lightning hole was associated with an intense, non-tornadic supercell on 6 April 2003. This feature was nonexistent from all supercells analyzed during the 13 October case. During tornadogenesis, the radar and LDAR II data indicated updraft weakening. The height of the 30 dBZ radar top began to descend approximately 10 minutes (2 volume scans) before tornado touchdown in one storm. Total lightning and CG flash rates decreased by up to a factor of 5 to a minimum during an F2 tornado touchdown associated with this storm. LDAR II source heights all showed descent by 2-4 km during a 25 minute period prior to and during this tornado touchdown. This drastic trend of decreasing source heights was observed in two tornadic storms prior to and during tornado touchdown, but did not occur in non-tornadic supercells, suggesting that these parameters can be useful to forecasters. These observations agree with tornadogenesis theory that an updraft weakens and the mesocyclone can become divided (composed of both updraft and downdraft) when a storm becomes tornadic. LDAR II source density contours were comma-shaped in association with severe wind events within mesoscale convective systems (MCSs) on 13 October 2001 and 27 May 2002. This signature is similar to the radar reflectivity bow echo. Consistent relationships between severe weather, radar and lightning storm characteristics (i.e., lightning heights) were not found for cells within MCSs as was the case for supercells. Cell interactions within MCSs are believed to weaken these relationships as reflectivity and lightning from nearby storms contaminate the cells of interest. It is also more difficult to clearly define a cell within an MCS.

Download or read book Analysis and Assessment of Peak Lightning Current Probabilities at the NASA Kennedy Space Center written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-18 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: This technical memorandum presents a summary by the Electromagnetics and Aerospace Environments Branch at the Marshall Space Flight Center of lightning characteristics and lightning criteria for the protection of aerospace vehicles. Probability estimates are included for certain lightning strikes (peak currents of 200, 100, and 50 kA) applicable to the National Aeronautics and Space Administration Space Shuttle at the Kennedy Space Center, Florida, during rollout, on-pad, and boost/launch phases. Results of an extensive literature search to compile information on this subject are presented in order to answer key questions posed by the Space Shuttle Program Office at the Johnson Space Center concerning peak lightning current probabilities if a vehicle is hit by a lightning cloud-to-ground stroke. Vehicle-triggered lightning probability estimates for the aforementioned peak currents are still being worked. Section 4.5, however, does provide some insight on estimating these same peaks.Johnson, D. L. and Vaughan, W. W.Marshall Space Flight CenterLIGHTNING; ELECTRICITY; PROBABILITY THEORY; NASA PROGRAMS; SPACE SHUTTLES; AEROSPACE VEHICLES; LAUNCHING BASES

Download or read book First Cloud To Ground Lightning Timing Study written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA's LSP, GSDO and other programs use the probability of cloud-to-ground (CG) lightning occurrence issued by the 45th Weather Squadron (45 WS) in their daily and weekly lightning probability forecasts. These organizations use this information when planning potentially hazardous outdoor activities, such as working with fuels, or rolling a vehicle to a launch pad, or whenever personnel will work outside and would be at-risk from lightning. These organizations would benefit greatly if the 45 WS could provide more accurate timing of the first CG lightning strike of the day. The Applied Meteorology Unit (AMU) has made significant improvements in forecasting the probability of lightning for the day, but forecasting the time of the first CG lightning with confidence has remained a challenge. To address this issue, the 45 WS requested the AMU to determine if flow regimes, wind speed categories, or a combination of the two could be used to forecast the timing of the first strike of the day in the Kennedy Space Center (KSC)/Cape Canaveral Air Force Station (CCAFS) lightning warning circles. The data was stratified by various sea breeze flow regimes and speed categories in the surface to 5,000-ft layer. The surface to 5,000-ft layer was selected since that is the layer the 45 WS uses to predict the behavior of sea breeze fronts, which are the dominant influence on the occurrence of first lightning in Florida during the warm season. Due to small data sample sizes after stratification, the AMU could not determine a statistical relationship between flow regimes or speed categories and the time of the first CG strike.. As expected, although the amount and timing of lightning activity varies by time of day based on the flow regimes and speed categories, there are extended tails of low lightning activity making it difficult to specify times when the threat of the first lightning flash can be avoided. However, the AMU developed a graphical user interface with input from the 45 WS t