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<br />e <br /> <br />4. 30-60 minutes. - The greatest difference in precipitation at the <br />ground wi 11 occur during thi s period with the precipitation rate and <br />duration in seeded cases exceeding those in un seeded cases. The increase <br />in precipitation occurs from the early initiation of the precipitation <br />process. No microphysical differences will be found by the aircraft above <br />the freezing level during this period. <br /> <br />5. 1-3 hours. - In the period from 1 to 3 hours after treatment no <br />measurable difference will exist between treated and natural clouds by the <br />aircraft, radar, or precipitation gages. <br /> <br />. <br /> <br />D. Dynamic Effects <br /> <br />We postulate that no significant dynamic effects occur in the treated <br />clouds. Dynamic effects are expected to be negl i gib le because gl aci at ion <br />of the supercooled liquid water content is a relatively slow process (10 to <br />20 minutes) and because the water contents are very low. A further obstacle <br />to dynamic effects is the dry, stable layer which frequ3ntly limits cloud <br />tops to <4 km. The typical SCPP-1 cloud with 0.5 g/m , when glaciated <br />isobarically and instantaneously at -10 oC and 600 mb, would warm the cloud <br />only 0.5 Oc (Orville and Hubbard, 1973). The actual valu~s are expected to <br />be much less than this. Rapid glaciation and release of latent heat would <br />on 1 y occ ur in the presence of 1 arge unfrozen drops wi th droplets >500 Il m <br />having large enough surface areas to sweep out the seeding crystals. <br /> <br />. <br /> <br />13 <br />