Showing papers on "Thunderstorm published in 1971"

METROMEX: an Investigation of Inadvertent Weather Modification

Abstract: METROMEX, a field project designed and now in progress at St. Louis, involves 4 research groups planning and working cooperatively to study inadvertent weather modification by urban-industrial effects, and, in particular, man-made changes of precipitation. Urban areas affect most forms of weather and some, such as winds, temperature, and visibility, are obvious and their changes are easily measured. inadvertent precipitation changes are harder to measure, and except for the well-documented La Porte anomaly, urban-related rain changes have had only limited study. Examination of historical data at St. Louis has revealed summer increases in the immediate downwind area of. 1) rainfall (10–17%); 2) moderate rain days (11–23%); 3) heavy rainstorms (80%) 4) thunderstorms (21%); and 5) hailstorms (30%). METROMEX field measurements in the summer of 1971 involved 220 raingages and hailpads, 3 radar sets, 70 rainwater collectors, 14 pibal stations, 4 meteorological aircraft, unique atmospheric tracers, and ...

Is Ball Lightning caused by Antimatter Meteorites

Abstract: ALTSCHULER et al.1 suggest that ball lightning2–5 arises from a concentration of short lived radioactive isotopes produced by lightning and imply a need for radiation measurements near thunderstorms and tornadoes. We wish to report measurements of this type which have been made for about 12 months to test the hypothesis that ball lightning is caused by the annihilation of minute fragments of meteoritic antimatter from the upper atmosphere.

Considerations regarding solar and lunar modulation of geophysical parameters, atmospheric electricity and thunderstorms

Abstract: The basic thesis of this paper is that the proper scope of meteorology should include, besides the earth's atmosphere, the sun's atmosphere (the solar corona), the associated interplanetary magnetic field, and lunar modulation of this environment. Recent advances in space science have enabled us to make direct measurements in this region for the first time. The shape and characteristics of the magnetosphere have been completely redefined during the last ten years from a simple magnetic dipole to the present model with an elongated tail stretched out by the solar wind. The interplanetary magnetic field has been defined with its spiral structure and sectors tied into the solar surface. This provides a magnetic link between the sun and earth. It is probable that extra-terrestrial factors do play a role in regulating weather, although the extent of this influence remains to be determined. Possibly such effects are most significant or easily detectable in the realm of atmospheric electricity. In view of the limitations in our present knowledge of all the variables responsible for regulating weather, it would seem appropriate to pursue the study of extra-terrestrial influences. Such research could lead to a better understanding of atmospheric circulation, precipitation mechanisms and thunderstorms. The field of meteorology which might particularly benefit from such research is long range weather forecasting.

Thunderstorm-environment interactions determined from aircraft and radar observations

Abstract: Aircraft measurements at low- and mid-cloud levels near two isolated and persistent Great Plains thunderstorms concurrently scanned by radar are analyzed to determine the kinematic properties of the near-cloud air flow, the moisture budget, and the dynamical interactions between the cloud and its surroundings. Time variation in velocity divergence, relative vorticity, and moisture flux convergence in the subcloud layer relate well to changes in storm development and translation. Aircraft winds and radar chaff trajectories substantiate the premise in some models that mature thunderstorms, moving more slowly than ambient winds, divert and distort mid-tropospheric air motion in a manner similar to solid obstacles in relative streaming flow. Observed ingestion of mid-tropospheric air motion tracers demonstrates that, at the same time, internal circulations aloft are not entirely insulated from the environment. A graphical synthesis of three-dimensional air flow within and around a typical Great Plain...

Dynamical Analysis of Outflow from Tornado-Producing Thunderstorms as Revealed by ATS III Pictures

Abstract: Detailed synoptic and dynamic analyses of outflow from tornado-producing thunderstorms of 23 April 1968 were made by using conventional rawinsonde data combined with ATS III pictures. It was found that the pre-existing flow at the cirrus level over storm areas changed dramatically into outflow as the storms developed. When the storms reached their mature stage, the horizontal dimensions of the outflow increased to ∼500 km, Detailed analyses of rawinsonde data inside the outflow area revealed the existence of a mid- tropospheric warm core accompanied by a significant field of convergence below the 700-mb surface. Quantitative analysis of the thermodynamical and dynamical aspects of the outflow field showed that the outflow was induced and maintained by convective warming.

Lightning observations by satellite.

Abstract: Lightning observation by OSO-E satellite, suggesting maximum thunderstorm incidence over North Atlantic Ocean

The Effect of an Urban Area on the Precipitation from a Moving Thunderstorm

Abstract: A case study of a thunderstorm cloud on 9 September 1955 was made to investigate the effect of London's urban area on its growth and precipitation amounts. Radar evidence was used to follow the development of the cloud, and dense observation networks provided data on synoptic meteorological elements and rainfall amounts. The cloud originated to the west of London and moved eastward with the mid-tropospheric wind. As it crossed the city, rapid growth occurred and precipitation amounts were heavy. The cloud growth was due to the high values of potential and wet-bulb potential temperatures in the urban area. It is concluded, in this case, that the urban effect was real, but it is stressed that generalization from this conclusion may not be valid.

Mesoscale Modification of Synoptic Situations from Thunderstorm Development as Revealed by ATS III and Aerological Data

Abstract: Synoptic and dynamic aspects of the development of the tornado-producing thunderstorms of 23 April 1968 were studied by combining conventional observation data with ATS III pictures, with special emphasis on the interaction between the thunderstorms and the large-scale field. Results of the analysis revealed a significant modification of the moisture, thermal and wind fields in the vicinity of the area where storms developed. The formations of the large-scale cloud band and moist tongue were due to the mesoscale convective disturbances that developed along the frontal zone. It was concluded that the formation of a mid-tropospheric warm core accompanied by a strong upper outflow was the result of a process of so-called convective warming. Results of the analyses suggested that both the jet stream and the core of positive vorticity to the left of the jet stream were formed by the increased thermal gradient to the left of the warm core. It was inferred that the modified thermal and vorticity fields ...

Ionospheric Disturbances in the.F2 Region Associated with Severe Thunderstorms

Abstract: Radio observations are reported at two locations during June 1969, one near Concordia, Kan, and the other near Oklahoma City It is found that ionospheric waves are observed when thunderstorms with tops (radar height) greater than 40,000 ft are occurring within a radius of 200 km The waves have periods in the range of 1 min to about 5 min and are detected as a Doppler shift in the ionospheric radio echoes Spectrum analysis of the storms indicated that, in general, there are two peaks of infrasonic power which occur at periods of 36 and 45 min

Identification of preferred areas of shower development by means of high power radar

Abstract: A high-power, high-gain radar has been used to investigate clear air echoes on days when surface heating produced low-level convection. The echoes were from irregular refractive index gradients produced primarily by gradients of water vapour density of small scale (5 cm). It was observed that the height to which the convection extended was revealed by an almost continuous layer of echo. This layer was perturbed on a scale of kilometres by individual convective elements; in addition Areas of Deeper Convection (termed ADCs) some tens of kilometres across occurred. These features are described in this paper. Individual ADCs were identifiable as entities for several hours, and, on the one occasion when reliable movements could be determined, they travelled with the low-level wind. When the vertical structure of the atmosphere was such that showers occurred, they developed only within ADCs. Evidently the showers occurred in clusters because of the pre-existing structure of the convective layer and not because individual showers modified their near environment. On two of the four occasions studied the ADCs could be related directly to topographical features. In one case of negligible wind an ADC developed and remained close to hills; on another occasion a plume-like area of deeper convection over 100 km long appeared to stream away from high ground. More generally, however, advection of ADCs masked possible topographical influences. It is suggested that by using a high power radar to identify ADCs it may be possible to forecast the location of outbreaks of showers and thunderstorms more precisely than is possible at present. Further lines of research are also proposed.

The variation of the electric field after lightning and the conductivity within thunderclouds

Abstract: It has been found that the rate of growth of field following a close lightning discharge is explicable in terms of the regeneration of the dipole by a constant current and a charge loss governed by the fair weather conductivity at the height of the charge. The recovery may be influenced by local point discharge after large field-changes, but the presence of a core of high conductivity within the cloud need not be invoked. The recovery curves from close flashes are found to be rather irregular and no really useful information concerning the currents generating the dipole of the thunderstorm can be derived from them. As the distance of the storm increases then the recoveries become much more rapid and of reproducible shape. It is suggested that after the discharge the re-arrangement of the space charge existing because of the conductivity gradient in the atmosphere is responsible for the change of the field observed. Some numerical work gives fair agreement with the observed functional dependence of the initial rate of recovery on the size of the field change. These distant recoveries are the response of the conducting atmosphere to the field change, and can give no useful information about the thunderstorm itself.

Water vapor - Stratospheric injection by thunderstorms.

Abstract: 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 Admninistration Convair 990 jet laboratory, extended over a sample size much larger than that possible by balloon and other techniques.

the effect of weather on the operations and economics of air transportation today

Abstract: Technical improvements in aircraft and navigational and airport aids have eliminated most of the problems of adverse weather which the air transportation industry faced 30 years ago. In spite of this progress, nature is still capable of setting up hostile environments for aircraft operations. Such elements as thunderstorms, fog, turbulence, snowstorms, heavy rain, and high winds can close airports, divert flights and cause disservice to passengers. Using typical cases, the full effects of weather interruptions are discussed and related to the present day United States fleet of 2400 transports, and to their control. Recent economic studies provide a basis for assessing the cost of several weather factors which interfere with scheduled air transportation.

Spherical capacitor hypothesis of the earth's electric field

Abstract: Stemming from the suggestion that the earth-ionospheric fair weather field arises from the lowest order resonant excitation of the earth-ionosphere cavity by lightning, it is shown that the same field is generated through electrostatic induction by equivalent charge dipoles from thunderclouds in the earth's atmosphere An electrostatic induction model was used to derive from known worldwide thunderstorm data the magnitude of the expected earth-ionosphere fair weather potential A value of only approximately one third of the observed potential was obtained Possible sources of the discrepancy are suggested

Polarization of 500 kHz Electromagnetic Noise from Thunderstorms: A New Interpretation of Existing Data

Abstract: It has been widely accepted that electromagnetic noise at low radio frequencies from thunderstorms is mainly vertically polarized. This paper re-examines the existing 500 kHz data of Kohl, taking into account the electrical conductivity of the earth. The corrections involved are shown to be crucial, revealing that Kohl's data actually infer that the vertical component of the rf electric field is several times smaller than its horizontal component. This result is of importance in understanding the relationship between the electromagnetic noise spectrum generated by lightning and the details of the stroke process. The physics of the calculated correction is discussed, as well as the limits of validity for the calculation. Experiments to measure the polarization ratio for other types of terrain are suggested and the theory is used to predict a value for the expected ratio for the midwestern United States.

Thunderstorm Water Contents and Rain Fluxes Deduced from Radar

Abstract: Total instantaneous water contents of several intense thunderstorms were calculated from smoothed representations drawn from quantitative radar observations; values typically ranged from 108–109 kg. Rain rates and accumulations were obtained from reflectivity measurements near the surface. The rainfall rates of the storms were about 105–106 kg sec−1 with total accumulations averaging 109–1010 kg. Dimensions and durations of the storms are also given.

Ball Lightning in the Prescientific Era

Abstract: Lightning flashes appear in divers forms during thunderstorms. The observation of the different shapes led to their classification as different types of lightning even in ancient works which no longer exist and are only known from references in later writings. Three general forms, for example, are represented by the ordinary lightning stroke, often called zigzag lightning, which is seen in a bright well-defined path; sheet lightning, which is faintly luminous and covers a broad region of the sky; and ball lightning, which glows either faintly or very brightly but presents a very distinctive appearance both in shape and in its varied paths. Etr.uscan art shows such types of lightning, including the ball of fire.(160) A discussion of ball lightning is attributed to Aristotle in the fourth century B.C. in his work on meteorology. (17)

Regional Differences in Runoff-Producing Thunderstorms Rainfall in the Southwest

Abstract: INTRODUCTION Regional differences in rainfall amounts and intensities in the Southwest have been noted by numerous investigators. However, quantitative descriptions of these differences, usually as depthduration frequencies, generally have ignored differences in the storm system that generated the rainfall and have lumped essentially different storm populations together. Sellers (1960) suggested that rainfall in Arizona could be subdivided into roughly three categoriesfrontal winter rainfall, air -mass thunderstorm rainfall, and frontalconvective rainfall. Frontal -convective storms include those that result from tropical storms off Baja California and occasionally, as described by Sellers (1960), come "rampaging through southern Arizona." In this paper, estimates by Leopold (1944) and Hershfield (1961) of rainfall depthduration frequencies for Arizona and New Mexico are compared with more recent rainfall records from U.S. Weather Bureau rain gages in southern Arizona and New Mexico and Agricultural Research Service rain gages on the Walnut Gulch Experimental Watershed in southeastern Arizona and the Alamogordo

Storm Lightning and the Problem of Ball Lightning

Abstract: The immense thunderstorms which occur in nature contain huge electrical machines whose activity is displayed in lightning discharges. The intensity of electrical activity is beyond question to observers who are left with ears ringing and eyes blinded, such as the witness to a cannonade of flashes who noted two hundred lightning strokes in a minute or the one who reported displacement of a massive stone wall over several feet by a single discharge.

Instability line Thunderstorms in Natal

Abstract: Atmospheric circulations responsible for instability line formation in Natal are examined and instability release mechanisms and movement characteristics of associated storms are discussed. A thunderstorm model adapted after Newton (1960) is used to explain the west-east movement of storms to the left of winds in the middle and upper troposphere. It is suggested that these storms may reach the coast if regenerated by the in-phase occurrence of a passing coastal low.

Would Shower Cores or Relativistic Monopoles Produce Straight Lightning

Abstract: The cause of leaders occasionally leaving old stroke channels is found to be atomic and molecular negative ions inside and outside old stroke channels, respectively. From this it is shown that the ionization in shower cores and possibly that in monopole paths would be capable of carrying a lightning leader which would then be straight and result in a straight return stroke. Artificial initiation of lightning shows that even thunderclouds without spontaneous lightning maintain large potential gradients over large areas for significant periods of time. Thundercloud conditions for straight lightning may be more favorable over ocean than land areas.