Nighttime Observations of Thunderstorm Electrical Activity from a High Altitude Airplane
Abstract
Two sets of observations from a NASA U-2 airplane flying at approximately 20 km altitude over nocturnal thunderstorms are reported. Photographs show frequent lightning activity in the upper part of the cloud. In some cases, only the diffuse illumination produced by the lightning can be seen. In other cases unobscured segments of lightning channels 1 km or longer are visible in clear air around and above the cloud. Multiple images of lightning channels, accidentally displaced on the film during transport of the film in the camera, indicate multiple discharges in_the_same channel. Photographs taken through a diffraction grating show that the lightning"has a spectrum similar to that which has been observed in the lower troposphere. Lightning spectra obtained with a slitless line-scan spectrometer show strong singly ionized nitrogen emissions at 463.0 and 500.5 nm. Field changes measured with an electric field-change meter correlate with pulses measured with a photocell optical system. Optical signals corresponding to dart leader, return stroke, and continuing current events are readily distinguished in the scattered light emerging from the cloud surface. The variation of light intensity with time in lightning events, such as dart leaders, which radiate light first from a location within the cloud and later from outside (beneath) the cloud are consistent with the predicted modification of optical lightning signals by clouds as given by Thomason and Krider.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1984
- Accession Number
- ADA542979
Entities
People
- B. Vonnegut
- Chandler Sours Rhodes
- M. Brook
- O. H. Vaughan Jr.
- R. E. Orville
Organizations
- National Aeronautics and Space Administration