WMOD00311

• Title: Harold D. Orville Symposium - Forty Years of Modeling Clouds and Weather Modification
• Date: 4/26/2003
• Weather Modification - Doc Type: Report

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About the Cover

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The cover figure represents the development of numerical models by the numerical
modeling group at the Institute of Atmospheric Sciences. The 1960s panel shows a
result for the initiation of a cloud over a 3000-foot mountain ridge. The primary
airflow is from left to right so that the cloud forms over the right mountain slope. The
1970s result is for our simulation of a rain shower in a 10 km by 10 km domain that
includes the same size mountain ridge as the previous result. The shaded region
depicts the rain field. The 165 number in the upper right comer indicates that the
results are for 165 minutes of simulated real time. The next panel shows results for
the numerical simulation of a hailstorm, published in 1977. The dashed lines are
streamlines and the solid line outlines the storm. The darker symbols, extending from
deep in the cloud to near the surface, indicate hail falling out of the cloud with some
melting into rain over the mountain ridge. Some rain to the right of the ridge is being
recycled back into the cloud. The domain is 20 km by 20 km. The 1986 color panel
shows the total condensate in a numerical simulation of a thunderstorm that produced
a strong microburst near Huntsville, Alabama. The dark red region indicates copious
amounts of precipitation falling out of the storm to create strong outflow at the earth's
surface. The last panel (1990s) shows three-dimensional modeling results after two
hours of real-time simulation of a North Dakota hailstorm on a grid 60 km on a side
and 20 km deep. The dynamics of the model is that of Terry Clark at the National
Center for Atmospheric Research and the microphysics is that of the lAS, Richard
Farley the principal investigator.

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