WMOD00424

• Project Name: 1978 Delaware Rain Augmentation Project
• Title: 1978 Delaware Rain Augmentation Project - Condensed Report
• Prepared For: Secretary of Agriculture, State of Delaware
• Prepared By: Dr. Larry G. Davis, Lawrence B. Youngren
• Date: 12/1/1978
• State: DE
• Country: United States
• Weather Modification - Doc Type: Report

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of equal reflectivity. The uppermost contour denotes the echo top.
The other contours are for values 10, 20, 30 and 40 dbz.
The time-height cross sections of the radar reflectivity
are very useful in the interpretation of the precipitation proeesses
active at the time of seeding. For example, if the initial echo
pattern (FE=first echo) is located below the _50 to -10oC altitude,
one can infer that precipitation size particles are being generated by
the warm rain process (condensation/coalescence). Similarily, if
the first echoes (FE) occur at higher altitudes where temperatures
are near _20oC, one can infer that the ice phase process (iniltiation
of graupel and subsequent riming) has probably contributed to the
initiation of precipitation size particles.
Cloud tops, echo duration, precipitation fallout
patterns, etc., can be estimated from these diagrams and then used
in the interpretation of the seeding events.

4.5 Cloud Base and Cloud Top Observations
Measurements of cloud base altitudes and temperatures
were derived from the airborne data tapes (voice recordings and
computer printout of altitude and temperature). Cloud tops were
derived from selected RBI measurements. Temperatures corres-
ponding to cloud tops were derived from the respective Dulles sound-
ing. A summary of these observations is presented in Table ill in
Section 3.1.

4. 6 Film Data
Super 8-mm time-lapse photos were made of the
remote PPI scope. These films were useful in previewing the echo
characteristics for a given case but proved to be too lpw in quality
for detailed studies. Thus the plastic overlays were used in the
echo history studies.

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