WMOD00538

• Title: Remote Sensing fo Gravity Waves and their Effect on Cloud Development
• Date: 5/1/1978
• Weather Modification - Doc Type: Report

of satellite-observed gravity waves. He observed four types of
gravity wave generating mechanisms (see figure 5):

A. Thunderstorm-mesohighs
B. Jetstream shear zones
C. Diverging jetstreams
D. Intersection of diverging jets with subtropical jets

Although waves were found when these phenomena were present, it was
assumed that many other phenomena may generate waves when atmospheric
moisture and stabil ity are unfavorablE! for cloud production.
Because of this reason, gravity waves are believed to be much more
numerous than those visible in satell~ite pictures. Gravity waves
may take two forms, either white line propagation, in which case the
moisture-laden air is lifted to condensation and clouds develop, or
dark line propagation when downward motion dissipates the existing
clouds through evaporation. This form of +esonance between thE!
production of enhanced or suppressed convection depends on a rE!l ation-
ship between the phase of the gravity wave and the stage of convective
development (figure 6). It. is important in forecasting and in the
evaluation of weather modification experiments. Knowledge of the
gravity wave structure may permit better prediction of the natural
convective development and its dissipiition. A priori knowledge of
these natural conditions also aids in the evaluation of "true"
seeding effects.

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