All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 193 18 0
PDF Downloads 25 13 0

Preliminary Tests of a Cumulus Cloud Seeding Technique

G. A. IsaacAtmospheric Environment Service, Downsview, Ontario, Canada M3H 5T4

Search for other papers by G. A. Isaac in
Current site
Google Scholar
PubMed
Close
,
R. S. SchemenauerAtmospheric Environment Service, Downsview, Ontario, Canada M3H 5T4

Search for other papers by R. S. Schemenauer in
Current site
Google Scholar
PubMed
Close
,
C. L. CrozierAtmospheric Environment Service, Downsview, Ontario, Canada M3H 5T4

Search for other papers by C. L. Crozier in
Current site
Google Scholar
PubMed
Close
,
A. J. ChisholmAtmospheric Environment Service, Downsview, Ontario, Canada M3H 5T4

Search for other papers by A. J. Chisholm in
Current site
Google Scholar
PubMed
Close
,
J. I. MacPhersonNational Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6

Search for other papers by J. I. MacPherson in
Current site
Google Scholar
PubMed
Close
,
N. R. BobbittNational Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6

Search for other papers by N. R. Bobbitt in
Current site
Google Scholar
PubMed
Close
, and
L. B. MacHattieCanadian Forestry Service, Ottawa, Ontario, Canada K2P 1X4

Search for other papers by L. B. MacHattie in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

A cloud seeding technique is proposed which has the objective of stimulating rainfall from cumulus clouds drifting over forest fires. Preliminary tests of the ice crystal production capability of the cloud seeding technique were conducted on five cumulus clouds near Yellowknife, N.W.T., Canada, during July 1975. These clouds were over forest but not near forest fires. A T-33 turbulence research aircraft performed the seeding by burning wing-mounted TB1 AgI flares while flying through the clouds at the −5 to −10°C level. The T-33 turbulence measurements enabled estimates to be made of the rate of dispersion of the AgI. Microphysical measurements were made before and after seeding by an instrumented DHC-6 Twin Otter aircraft flying at the seeding level, and these were compared with measurements in six untreated cumulus clouds. High concentrations of ice crystals appeared after seeding in four of the five seeded cumulus clouds, and on two occasions precipitation-sized particles appeared at the seeding level. The evidence indicates that the AgI aerosol produced large quantities of ice crystals.

Abstract

A cloud seeding technique is proposed which has the objective of stimulating rainfall from cumulus clouds drifting over forest fires. Preliminary tests of the ice crystal production capability of the cloud seeding technique were conducted on five cumulus clouds near Yellowknife, N.W.T., Canada, during July 1975. These clouds were over forest but not near forest fires. A T-33 turbulence research aircraft performed the seeding by burning wing-mounted TB1 AgI flares while flying through the clouds at the −5 to −10°C level. The T-33 turbulence measurements enabled estimates to be made of the rate of dispersion of the AgI. Microphysical measurements were made before and after seeding by an instrumented DHC-6 Twin Otter aircraft flying at the seeding level, and these were compared with measurements in six untreated cumulus clouds. High concentrations of ice crystals appeared after seeding in four of the five seeded cumulus clouds, and on two occasions precipitation-sized particles appeared at the seeding level. The evidence indicates that the AgI aerosol produced large quantities of ice crystals.

Save