Superfog webinar

New Superfog Screening Tool – Development and Validations through Laboratory Experiments
Wed, Feb 12, 2014 3:00 PM – 4:00 PM CST
Marko Princevac and Christian Bartolome will present a webinar on superfog. Superfog is a dense smoke cloud that reduces visibility to less than 10 feet. Major car pile ups, such as ones in Florida on the Interstate Highways 4 and 75 in 2008 and 2012, have resulted due to the formation of a Superfog.  Here we will present laboratory modeling efforts that have been conducted to explain the origins of Superfog and that led to the development of a new screening tool. Thermodynamics of water vapor, droplet size distribution, liquid water content, extinctions coefficients and boundary layer development were explored.  Wind tunnel measurements of smoldering smoke and smoke boundary layer growth have been conducted for various environmental and fuel conditions. In these experiments the favorable conditions for the Superfog formation were determined to be: fog droplet sizes less than 1 μm, minimum cloud condensation nuclei concentrations of 105 per ccm, liquid water content greater than 2 g kg-1, ambient temperature less than 40oF, ambient humidity greater than 80%, fuel moisture contents greater than 40% by mass, and wind velocities less than 1 m s-1 (2.2 mph). The Superfog Analysis Model (SAM) has been developed to aid land managers to quickly assess situations as favorable or unfavorable to the formation of Superfog.  SAM has been validated by laboratory experiments and has been successful in predicting previous Superfog events.  A brief demonstration of SAM usage will be also given.