Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “thunderstorm”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

The thunderstorm forecasting system at the Kennedy Space Center.

One of the major problems concerning meteorologists at the Kennedy Space Center, Fla, involves the forecasting of thunderstorm activity and associated adverse weather phenomena. The purpose of the study is to outline some of the more successful diagnostic tools which have been developed to aid the forecaster. These involve a variety of statistical procedures including conditional probabilities, exposure-period probabilities, and systems of multiple-regression equations based on nonlinear predictors.

Charles J Neumann↗
NASA NTRS1971

Water vapor - Stratospheric injection by thunderstorms.

Infrared radiometric inference measurements of the mass of water vapor injected into the lower stratosphere and upper troposphere by a number of plains thunderstorms show an average threefold increase over the fair weather background mass of water vapor. These airborne measurements, made from the National Aeronautics and Space Administration Convair 990 jet laboratory, extended over a sample size much larger than that possible by balloon and other techniques.

Kuhn, P. M.↗
NASA NTRS1973

Electric radiation fields of lightning return strokes in three isolated Florida thunderstorms

Peak value and risetime distributions for the electric radiation fields produced by lightning strokes to ground in three isolated Florida thunderstorms are presented. The storm at 195 km produced about 1000 return strokes having an average peak radiation field (normalized to 100 km) of about 5.5 V/m, the storm at 110 km produced about 700 strokes having 2.0 V/m, and the storm within 10 km produced about 100 strokes having 15.0 V/m. For each storm the average peak radiation field for first strokes was only slightly greater than the average peak field for subsequent strokes. For the sample of three storms the average peak radiation field in a given storm was proportional to the number of subsequent strokes per flash in that storm. The field risetimes for the two distant storms have statistical properties which are essentially identical to those reported for distant storms in Pennsylvania, whereas the close Florida storm exhibited significantly faster risetimes.

Lin, Y. T.↗
NASA NTRS1974

A Bayesian analysis of two probability models describing thunderstorm activity at Cape Kennedy, Florida

A Bayesian analysis of the two discrete probability models, the negative binomial and the modified negative binomial distributions, which have been used to describe thunderstorm activity at Cape Kennedy, Florida, is presented. The Bayesian approach with beta prior distributions is compared to the classical approach which uses a moment method of estimation or a maximum-likelihood method. The accuracy and simplicity of the Bayesian method is demonstrated.

Williford, W. O.↗
NASA NTRS1975

Lightning properties in Florida thunderstorms from video tape records

From video-tape recordings of lightning flashes to ground in convective daytime storms at the NASA Kennedy Space Center, Florida, and near Ocala, Florida, statistical data are presented for the flash-time duration, the number of strokes per flash, the time between all strokes, and the time between strokes having spatially separate channels. A daytime video tape 'photograph' of a stepped leader is reproduced. Finally, statistical data are presented for 13 long horizontal lightning discharges occurring along a line of nocturnal thunderstorms near Gainesville, Florida. These discharges all propagated horizontally near the freezing level (4.5 km) at an apparent average velocity between 5600 and 11,000 m/s for a typical distance of 2 to 3 km. Eleven of the 13 horizontal discharges were preceded by or occurred within 16.7 ms of a glow in the cloud roughly 0.5 km above the horizontal channel.

Brantley, R. D.↗
NASA NTRS1975

Solar modulation of atmospheric electrification through variation of the conductivity over thunderstorms

It is suggested that variations of the current in the global atmospheric electrical circuit can be produced through regulation of the resistance between the tops of thunderclouds and the ionosphere. Long- and short-term changes in the conductivity of this region occur due to changes in the ionization rate resulting from solar activity. Previous suggestions that the phenomena might be due to conductivity variations in the fair weather part of the world or an influx of space charge to the upper atmosphere are discussed and considered unlikely. It might be possible to test the proposed mechanism by measuring the temporal variation of the ionospheric potential during distributed solar periods. Another approach would be to measure simultaneously the variation in ionization rate and electric current over thunderstorms. Several ways in which changes in atmospheric electrification might influence other meteorological phenomena are mentioned.

Markson, R.↗
NASA NTRS1975

A numerical investigation of severe thunderstorm gust fronts

A numerical model was developed to simulate the evolution and structure of severe thunderstorm gust fronts. The model is a non-hydrostatic, fine resolution, cross-sectional primitive equation model. Two-dimensional horizontal and vertical equations of motion, the continuity equation, and the thermodynamic energy equation were utilized. It was shown that two dominant factors influencing gust front configuration are surface friction and the solenoidal field coincident with the front. It is suggested that solenoidal accelerations oppose the deceleration of surface friction. After a downdraft is initiated in the model, these opposing tendencies soon reach a balance and the gust front achieves a quasi-steady configuration. Thus, the experiments indicate that surface friction does not induce a cycle of front formation and collapse. In addition, the effect of evaporative cooling in producing a vigorous downdraft was parameterized by a local cooling function. Greater cooling in the downdraft results in a more intense gust front that exhibits stronger wind maximums and greater shears. The ambient air stability was shown to be an important factor influencing the depth of the cold outflow.

Mitchell, K. E.↗
NASA NTRS1975

Overshooting top behavior of three tornado-producing thunderstorms

The behavior of overshooting tops and jumping cirrus observed in three tornado-producing thunderstorms during the 1974 Learjet Cloud-Truth experiment is discussed. An investigation of temporal changes in the heights of overshooting domes (conglomerations of overshooting tops with diameters less than 1 km) reveals several distinctive features associated with tornadic events. There is a gradual decrease in dome height prior to tornado touchdown. Minimum dome activity occurred 5 min after, 5.5 min before, and at approximately the same time as the tornadic event in the storms observed. In all cases, dramatic dome growth at a rate of 17 to 23 m/sec immediately followed the occurrence of the minimum dome heights. There is evidence that tornado production is insensitive to the pre-touchdown maximum dome heights between 1 and 3 km.

Umenhofer, T. A.↗