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Dr. Paul Lawson is a Senior Research Scientist at SPEC Incorporated. 

H received a B.S. degree in Electrical Engineering from Michigan State University in 1969 and M.S. and Ph.D. degrees in Atmospheric Science from the University of Wyoming in 1972 and 1988.

He has been heavily involved in the development of instrumentation and analysis of meteorological data for more than three decades.

Dr Lawson has also authored or co-authored over 100 peer-reviewed papers and has participated in over 50 meteorological field programs as scientist and/or Learjet pilot. 

Dr Lawson is a past member of the American Meteorological Society (AMS) committee on cloud physics, and a member of over twenty NASA and NSF science teams.

Project Brief:

“Microphysics of Convective Clouds and the Effects of Hygroscopic Seeding”

SPEC investigates a new approach to rain enhancement that leverages ice production processes in cumulus clouds.

When large “supercooled” drops – drops that remain unfrozen at temperatures below zero degrees Celsius - form in clouds and freeze, they emit tiny ice particles.

These tiny ice particles then collide with other large supercooled drops, producing an avalanche process that freezes the remaining large drops, producing small hail stones.

The hail stones then melt into rain after they fall into the warm sub-cloud layer.

Seeding in the updraft at cloud base with water attracting material can facilitate the development of large drops that are required to generate the natural secondary ice process.

Using sophisticated instrumented aircraft and radar, this experiment studies this process in cumulus clouds in the UAE, and evaluate the potential for rain enhancement.

The operations are conducted in collaboration with Dr Hugh Morrison of the National Center for Atmospheric Research (NCAR) and Dr Roelof Bruintjes of Advanced Radar Corporation (ARC).

NCAR is providing numerical modeling support for the project, while the ARC is assisting the researchers through the provision of a flight scientist and analysis of radar data. 


Research Progress:

Since the start of his project, Dr Lawson’s research team has systematically investigated cumulus clouds with a large range of cloud base temperatures and drop distributions. In July and August 2017, the American team employed a Learjet research aircraft to study work convective clouds over the US with cloud base temperatures ranging between -6 and +12 C.

The research campaign saw a total of 108 cloud penetrations conducted with the important goal of determining what combination of temperatures and drop size distributions could potentially be treated by cloud seeding to produce large drops leading to enhanced rainfall.

The team has also been analyzing NCM radar data to identify optimal locations and times of day for a UAE flight campaign set to be conducted as part of a field project in 2019. The results gathered to date show that about 95% or first radar echoes (i.e., precipitation sized particles) occur in Omani airspace about 50 km east of the Al Ain airport.

A theoretical and numerical modeling study of the ascent rate of cloud thermals was also carried out. The results from this work was recently published in the Journal of the Atmospheric Sciences.

In addition, a Learjet 35A purchased for the UAEREP project has been converted to a research aircraft through gaining FAA approval for the installation of a suite of microphysical instruments.

To enable the use of these instruments, the aircraft was required to undergo extensive upgrades to its avionics.


Dr Lawson’s project is running according to plan with much of the foundational work nearing completion. In preparation for their field work in the UAE, the research support team at the NCAR is currently improving and refining the modeling schemes that will be used for cloud simulations over the UAE.

The team are incorporating these modeling studies and refinements of their Learjet aircraft and scientific instruments in preparation for their 2019 field project in the UAE.

The third year of this project will therefore be devoted to data analysis and numerical modeling, with the overarching objective being to determine what types of cumulus clouds are suitable for enhancing rain via hygroscopic seeding. 


For more information on the project please visit:

Full Report - PDF document.