58357 - Atmospheric Physics and Meteorology

Learning outcomes

At the end of the course, the student: - applies the knowledge of electromagnetism and quantum physics to the processes of absorption and emission of radiation by solids and gases; - knows the energy balance of the planet, energy exchanges with external space and the measures that are used to determine them, as well as their intrinsic limitations; - knows the conservation laws that underlie the dynamics and thermodynamics of the atmosphere and the main forms of instability; - knows the characteristics and properties of gravity waves, baroclines and Rossby waves; - will know the main types of numerical forecasting models of the weather and the problems related to the parametrizations used; - uses the acquired knowledge to interpret data measured by sensors for the study of the atmosphere and to interpret the output of weather forecasting models ; - uses the lecturer's texts and lecture notes written in English and acquires skills in communication on the subject, becoming aware of the English terminology in use; - develops simple models (thermodynamics, greenhouse effect) during exercises; - prepares a report at the end of the exercises and discuss it during the final test.

Course contents

The course is organized in 2 modules, the first of Atmospheric Physics and Meteorology and the second concerning the Synoptic Meteorology and introduction to Weather Forecasts.

Module 1 is structured as follows:

- Introduction to atmospheric physics and meteorology (history, transversal applications, open problems, opportunities offered by the LM FST). The observational system for the atmosphere (in situ and remote sensing measurements).

- Basic definition of radiometric variables, relationship between radiance and irradiance. Spectral radiance and irradiance. Elements of black body radiance. Examples. Sensitivity of the Planck function in various spectral intervals. Absorption and emission. Kirckhoff's law; local thermodynamic equilibrium (LTE) and application limits.

- Spectral irradiance of the sun at the top of the atmosphere. Instant and daily insolation: insolation distribution according to latitude and time.

- Basic model of planetary energy balance: emission temperature as a function of solar irradiance and planetary albedo. Role of atmospheric gases in modulating the long wave emission, the natural greenhouse effect and radiative forcing of greenhouse gases.

- Differential equation for extinction. Optical path and transmissivity. Extinction of direct solar radiation: Bouguer equation. Relevance of the phenomena of absorption and diffusion in the atmosphere as a function of the wavelength.

- The differential equation of radiative transfer in the presence of absorption and emission processes. Derivation of the Schwarzschild solution in the general case and for a plane-parallel atmosphere. Simulation of radiance measured on the ground and by satellite. Measurements of spectral radiance from satellite around the Earth and around Mars. Role of spectroscopy in the derivation of information from spectral radiance measurements.

- Radiative properties of natural and artificial surfaces. Presentation of the MSG satellite and the SEVIRI radiometer. In-depth discussion of SEVIRI images and multispectral image sequences. Typical phenomena of meteorology at mid-latitudes in satellite images: extratropical cyclones. Model of the Bergen school.

- Earth's energy balance in space. The measure of total solar irradiance: introduction to measurement techniques and limitations. Daily measurements of TSI by various sensors. Systematic errors and correlations between different data sets. Energy balance at the top of the atmosphere: definitions, measurement techniques and limitations. Examples of radiative budget measures (CERES) and zonal radiative budget.

- Average global energy balance of the atmosphere.

Module 2 is structured as follows:

Introduction to synoptic meteorology;

Atmospheric thermodynamics 

- Hypsometric equation

- Adiabatic processes and Dry Adiabatic Lapse Rate

- Wet processes

- Thermodynamic diagrams -

- Static thermal stratification: neutral, stable and unstable

- Conditional and convective instability

- Convective inhibition (CIN)

- Convective Available Potential Energy (CAPE)

Dynamics of synoptic systems

- Synoptic systems

- Equation of motion in vector form and in various coordinate systems

- Equation of continuity

- Equation for energy

- Scale analysis of the equations of motion

- Scale analysis of the continuity equation

- Vertical motions

- Equation for pressure tendency

- Solutions of the equations for the gradient wind; inertial wind; cyclostropic wind

- Geostrophic approximation

Elements of synoptics

- Fronts: definition and characteristics

- Cyclones: definitions and characteristics

- Extra-tropical cyclones

- Mediterranean cyclones

- Time maps and their interpretation

During the course there will be 3 laboratory exercises (4 hours each). Laboratory 1: interpretation of a radiosounding
Laboratory 2 and 3: reading weather maps (fronts, pressure systems at 850mb, 500mb, 350 mb).

Readings/Bibliography

The lecture notes (in English) of the teacher are available online.
The lecture notes also contain an extensive bibliography.

Atmospheric Science, an introductory survey. John M. Wallace and Peter V. Hobbs, second edition Academic Press 2006.

Teaching methods

Frontal lectures with extensive use of multimedia materials.
Classroom exercises with active student intervention.
More complex exercises on the climate in equilibrium conditions and on the thermodynamics of the atmosphere are carried out during the final laboratory.

Lectures can be held in English, if requested by the students.

Assessment methods

Written report on the activities carried out during the laboratory.
The verification is entrusted to a single oral examination for the two modules, consisting of a discussion on the report of the laboratory of module 1 and in free questions on the topics of the program that may also include the resolution of exercises.

Teaching tools

PC and video projector.
More complex classroom activities can be performed on a PC or with a personal notebook.

Office hours

See the website of Silvana Di Sabatino