58357 - Atmospheric Physics and Meteorology

Course Unit Page

SDGs

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

Climate Action

Academic Year 2021/2022

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 concerning the Fundamentals of Synoptic Meteorology, and the second on Atmospheric Radiative Transfer.

Module 1 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 synoptic meteorology:

- Fronts: definition and characteristics

- Cyclones: definitions and characteristics

- Extra-tropical cyclones

- Mediterranean cyclones

- Time maps and their interpretation

 

Module 2 is structured as follows:

1 Radiative transfer in atmosphere: basic definitions

  • Thermal and chemical structure of the atmosphere
  • Radiatively active gases
  • Electromagnetic spectrum
  • Sun solid angle
  • Monochromatic and total radiance and irradiance

2 The Sun

  • Sun luminosity and solar constant
  • Solar spectrum
  • Natural variation of solar total irradiance
  • Insolation

3 Black body and thermodynamic equilibrium

  • Maxwell Boltzmann distribution
  • Derivation of the Planck’s equation
  • Features of the black body model
  • Local thermodynamic equilibrium in the atmosphere

4 Absorption of radiation in the atmosphere

  • The law of absorption
  • Monochromatic transmissivity, absorptivity and reflectivity
  • Measures of solar radiation from the ground

5 Emission of radiation in the atmosphere

  • The source function
  • The Schwarzschild’s equation
  • Brightness temperature

6 Energy balance 1-D models

  • Radiative heating in the atmosphere
  • Radiative equilibrium of a planet
  • BDRF and spherical albedo
  • Earth emission

7 Greenhouse effect

  • Greenhouse parameter
  • Radiative equilibrium in a window grey atmospheric model

8 Climate sensitivity and feedbacks

  • Climate radiative forcing: external and anthhropogenic
  • Equilibrium response to radiative forcing
  • Volcanic eruption
  • CO2 forcing
  • Climate sensitivity
  • Feedbacks

9 Radiative time constant

  • Dark side temperature
  • Adiabatic and radiative lapse rate

10 Radiation and the Temperature profile

  • Multiple layers window gray model
  • Equiibrium temperature profile
  • Runaway greenhouse

11 Introduction to scattering

  • Scattering regimes
  • A simple scattering model

12 Energy balance

  • Global energy balance and Trenberth plot
  • Cloud forcing and feedback
  • Latitudinal mean distribution of radiative fluxes
  • Mean energy balance at the surface

13 Thermal escape

  • Mean free path of atmospheric molecules
  • The exosphere
  • Jeans mechanism

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 course.

Assessment methods

The verification is entrusted to a single oral examination for the two modules, consisting of free questions on the topics of the program.

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 Federico Porcù