CIFEX Experiment # 14

April 18, 2004.

Flight Scientist: V. Ramanathan

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Flight #20: Take off about 12:35 pm. Landed 3:50 pm

Objectives: Sample stratiform and cumulus clouds and detailed vertical profiling of Clouds under very Clean conditions. There was generally low level cumulus precipitation the past few days due to a cyclonic system and few fronts that followed. A front had just passed through Trinidad and another front was due west of us at about 350 km west of us. We planned to sample clouds in between the two fronts.

Multiple cloud layers were encountered throughout the flight. The cloud base was at about 2000 ft and extended to about 6000 feet close to the coast. Most of the clouds were precipitating. The precipitating cloud tops extended to about 8000 ft. Encountered CN as low as 100. CCN was also very low. After sampling below and in-clouds, spotted a cumulus cloud with a top of about 10000 ft and did a detailed vertical profiling with spiral flight pattern for about 30 minutes from 2.31 pm to 2.50 pm (21.31 GMT to 21.47 mt). Did a fly by over Trinidad head and flew over continental clouds over the Sierras and the precipitation was markedly low. This case can be used to study cumulus clouds under very low CCN levels. Did not see the brownish layer today.