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<br />.. <br /> <br />5. SEEDING ME'rHODOLOGY <br />All cloud seeding in the Texas HIPLEX area during the surrunl=r of 1978 <br />\ViII be accomplished by the use of silver iodide flares. The seeding \ViII <br />be classified as light (1-10 ice crystals per liter), heavy (greater than <br />or equal to 100 ice crystals per liter), and no seeding. Three airplanes <br />\ViII be available for seeding. An Aztec equipped \Vi th \Ving-mountE~d flares <br />and provided by CRMWD \Vill be available for seeding at cloud base " and a <br />Navajo provided by CRMlID and a Lear Jet provided by the Colorado Inter- <br />national Corporation \ViII be available for on-top seeding. <br />The sequence of the type of seeding (base or on top and amount of <br />silver iodide) to be done \ViII be detenmned in advance of the field pro- <br />gram. Prior to the field program, this sequence \ViII be kno\Vn only to <br />Mr. Riggio and the Project Director. The seeding sequence \ViII be put <br />in sequentially-numbered envelopes. An envelope \ViII be given to the <br />pilot of the seeding airplane irrunediately prior to each seeding mission <br />(see Section 7). After the pilot of the seeding airplane has selE~cted <br />the cloud to be seeded he \ViII open the envelope and, \Vithout revealing <br />its contents, proceed to seed the cloud in the manner specified in the <br />envelope. The purpose of this approach is to eliminate the possibility <br />of biases in observations or synoptic conditions. <br />Initial seeding of gro\Ving cumulus clouds \ViII be done \Vith vary- <br />ing amounts of silver iodide at the base and on top (not simultaneously) <br />to establish the amount of silver iodide required to achieve the desired <br />concentration of ice crystals. Follo\Ving this "calibration-type" seeding, <br />emphasis \ViII be placed on heavy on--top seeding of individual gro'Jling <br />cumulus clouds. <br />The selection of convective complexes (individual or group]! to be <br />seeded will be made in a manner similar to that for growing cumulus <br />clouds. Ho\Vever, the number of cases \ViII be considerably less tllan for <br />gro\Ving cumulus clouds. Two lines of convective complexes will be <br />treated with as many turrets as possible being seeded. <br />5.1 To\Vering Cumulus <br />5.1.1 Cloud Base <br />Cloud-base seeding will be accomplished with the Piper AztElC air- <br />plane operated by the Colorado River Municipal Water District. Silver <br />iodide crystals will be dispensed in the updraft under the visible cloud <br />by burning silver iodide flares mounted on each wing of the airplane. The <br /> <br />14 <br />