37377 - Atmospheric Pollutants Transportation and Dispersion Processes

Course Unit Page


This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Climate Action

Academic Year 2019/2020

Learning outcomes

This course provides the student with a basic knowledge of the fundamental principles necessary for calculating mass and energy balances involved in transport processes, basic notions of the physics of the lower atmosphere and the dispersion and deposition mechanisms of pollutants. This will enable the student to use the most widespread simulation models for atmospheric concentrations and ground deposition of pollutants and to compare the results with air quality reference values.

Course contents

Processes of transport and diffusion of pollutants in the Atmosphere.

Transport processes. Mass balance. Input, output and reaction flows. Common kinetic equations. Differential balance for individual components. Sedimentation; Stoke's Law. Dynamic and kinetic viscosities. Reynolds Number. Conductance and conductivity; salinity.

Molecular and turbulent diffusion. Fick's Laws. Factors influencing diffusivity. Atmospheric stability. Pasquill's Model for chimney plumes. Estimation of  ground pollutant concentrations as a function of distance from the stack and various parameters; computer simulations.

Energy balance. Bernoulli Equation for both incompressible fluids and gases. Decrease in atmospheric pressure and temperature with altitude. Bouyancy.

Variations in the distribution of volatile atmospheric components with altitude. Problem of ozone and relevant reaction cycles. Thermal energy; transport through thermal conduction, convection and irradiation (Stefan-Boltzmann and Wien laws); Greenhouse effect. Atmospheric pollution from combustion processes; Yields of Otto (petrol engine) and Diesel (diesel engine) Cycles.

Elements of the physics of the lower atmosphere: convective and diffusive layers. The geostrophic wind and the spiral of Ekman. Theoretical foundations of Gaussian models. Effective heights of plume emissions and the semi-empirical formulae for their estimation. Models for deposition under dry and humid conditions. Elements of air quality legislation and regulations. Methods of calculation for comparing modelling results and reference values of environmental regulations. Puff models, finite time emission models and particulate models.

Computer excercises on the various models for estimating air quality and ground depositions.


- Slides used for lectures, and partial use of:

- R. Francesconi, Appunti di Chimica Fisica Ambientale , CLUEB, Bologna, 2002.

- G. Finzi (a cura di): ”Gestione della qualità dell'aria”, MCGraw-Hill, 2001.

- S.R. Hanna, G.A. Briggs, R.P.Hosker Jr.: “Handbook on Atmospheric Diffusion”, U.S: Dept. Of Energy, NTIS, 1982.

Teaching methods

Lectures, tutorials, numerical exercises.

Assessment methods

Oral and single exam for the two parts (environmental physical chemistry and atmospheric physics) of the course.

Teaching tools

Slides, tutorials. A visit to the laboratories of ARPA (Ravenna) is also scheduled.

Office hours

See the website of Alberto Modelli

See the website of Massimo Andretta