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B. Vonnegut
,
C. B. Moore
, and
C. K. Harris

Abstract

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B. Vonnegut
,
C. B. Moore
, and
C. K. Harris

Abstract

No Abstract Available.

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B. Vonnegut
,
A. J. Illingworth
, and
P. R. Krehbiel

Abstract

No abstract available.

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J. D. McTaggart-Cowan
,
G. G. Lala
, and
B. Vonnegut

Abstract

An aircraft instrument is described that gives a real-time measurement of the number of ice crystal particles per unit volume in cirriform clouds. Its method of detection is based on the mechanisms of contact electrification, as applied to the collision between a stainless steel wire and an ice crystal. The signal conditioner, which employs a series of integrated circuits, converts the frequency of crystal collisions into a voltage. Several examples of actual flights are shown.

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B. Vonnegut
,
O. H. Vaughan Jr.
,
M. Brook
, and
P. Krehbiel

Motion pictures have been taken at night by astronauts on the space shuttle showing lightning discharges that spread horizontally at speeds of 105 m·s−1 for distances over 60 km. Tape recordings have been made of the accompanying optical pulses detected with a photocell optical system. The observations show that lightning is often a mesoscale phenomenon that can convey large amounts of electric charge to earth from an extensive cloud system via a cloud-to-ground discharge.

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C. B. Moore
,
B. Vonnegut
,
E. A. Vrablik
, and
D. A. McCaig

Abstract

Observations of thunderstorms in New Mexico were made with a vertically-scanning, 3-cm radar on a mountain top. Prior to a cloud-to-ground lightning discharge nearby, the radar echo overhead was usually quite weak, indicating low intensities of precipitation there. Following the lightning it was observed sometimes that in the region of the cloud where the discharge occurred the radar echo intensity rapidly increased, and shortly thereafter a gush of rain or hail fell nearby.

These studies confirm earlier radar observations, made by the authors at Grand Bahama Island, B.W.I., in which it was found that lightning is often followed in the cloud by a rapidly intensifying echo and then by a gush of rain at the ground. The increases in radar reflectivity in small volumes of the cloud following lightning suggest that the electric discharge is influencing the size of particles in the cloud.

An analysis indicates that within 30 seconds after a lightning discharge, the mass of some droplets may increase as much as 100-fold as the result of an electrostatic precipitation effect.

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B. Vonnegut
,
C. B. Moore
,
R. P. Espinola
, and
H. H. Blau Jr.

Abstract

Measurements of the electric potential gradient from a U-2 airplane flying over thunderstorms show that sustained gradients occurred only in the vicinity of convective cloud disturbances that rose above the stratiform anvil cloud. The potential gradient often reversed in polarity immediately after lightning occurred in the cloud. We interpret these effects as indicating the presence of a charged screening layer at the upper cloud boundary.

The observations further suggest to us that Wilson conduction currents flow from thunderstorms to the upper atmosphere for only as long as convection continues.

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H. J. Christian
,
R. L. Frost
,
P. H. Gillaspy
,
S. J. Goodman
,
O. H. Vaughan Jr.
,
M. Brook
,
B. Vonnegut
, and
R. E. Orville

In order to determine how to achieve orders of magnitude improvement in spatial and temporal resolution and in sensitivity of satellite lightning sensors, better quantitative measurements of the characteristics of the optical emissions from lightning as observed from above tops of thunderclouds are required. A number of sensors have been developed and integrated into an instrument package and flown aboard a NASA U-2 aircraft. The objectives have been to acquire optical lightning data needed for designing the lightning mapper sensor, and to study lightning physics and the correlation of lightning activity with storm characteristics. The instrumentation and observations of the program are reviewed and their significance for future research is discussed.

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