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Figure 2: A maze of long white clouds is Interwoven into !he uneven field of white that covers the Atlantic Ocean off the east coast of the United Slales These clouds are ship tracks. clouds that form around the exhaust released by ships Into the Sllll ocean air. Water molecules collect around !he bny particles (aerosols) from exhaust to form a cloud seed. More and more water aca.Jmulales on the seed unlll a visible cloud is formed Ship track.s prOVlde important clues about how human-produced aerosols affect cloud formation. When a large number of aerosol particles are In the atmosphere, water condenses onto a large number of "seeds' instead of gathenng around fewer, larger seeds. As a result. ship tracks are brighter or more reftecllve. carry more water, and may Inhibit rainfall. This Image was taken by MODIS on May 11. 2005. Credit: NASA. Fl9ure 3. NOAA-14 AVHRR rnicrqjlysical rendeong of a seeding track o~ Central China on 0735lJTC 14 Mard1 2001 The airaaft ftew genernIIy westward (lroo1 righllo left). Frool RDSeflfeld et al (2005). On 14'" March 2000, a cloud Seeding operation for preclpltaoon enhancement by aircraft was carried out in the Chaanxi Province of China A vivid cloud track appeared on satellite imagery: Its length was about 350km, and its average width was 9km (Figure 3). The operational aircraft was eqUipped With a silver iodide solution bumer and consumed 1200g of Agl. In Rosenfeld et. al. (2005) the satellite imagery is analyzed. Flgure 3a shows the microphysical rendering of the seeding track, with the seeded area appearing conspiOJously in red. embedded in the ambient supercooled layer clouds in yellow and orange colors. Figure 3b shows that the compoMion of the cloud within the seeding track was ice. resulting in a large effective radius of the doud-top particle that appears bright. This suggests that the seeded doud volume glaciated into ice hydrometeors that precipitated. Perhaps the greatest accomplishment of this observation is that gfaciogenic doud seeding using Silver iodide of thick supercooled layer clouds modified the doud microphysics to an extent that it could be dearly detected by the operational orbital weather satellites. The retrie....ed properties of lhe seeded track suggest that seeding glaciated the doud through a deep layer and initiated the precipitation process, as intended Rosenfeld el. al (2005). I I I I I I I l l l 4 The beginning of the SOAR program The Board of Directors of Sandy Land Underground Water Conservation District. South Plains Underground Water Conservation District, and the Llano Estacado Underground Water Conservation District ha....e participated with the High Plains Underground Water Conservation District #1 for a number of years in their preciprtation enhancement program. Convinced from past assessments that precipitation enhancement is a potential water management 1001. the three boards decided that a program beginning in 2002, apart from the High Plains would be benefICiaL On January 31. 2002 a permit was issued authorizing a program to oonduct rainfall enhancement. Additionally. with the cooperation of the State of New Mexico, an area west of Gaines County and Yoakum 4 4 4 4 4 4 4 4 4 4 4 4 4