Plumes gaussiani Plumes gaussiani nell’arianell’aria

FISICA AMBIENTALE 1

Antonio Ballarin Dentia.ballarindenti@dmf.unicatt.it

Horizontal transport of pollutants in the atmosphere

Distance Time scale

SecondsHoursDays

MonthsYears

1 – 10 m3 – 30 km

100 – 1000 kmHemisphere

Globe

Vertical transport of pollutants in the atmosphere. Time scales for vertical transport of pollutants from the ground to the layers indicated. The boundaries of the layers vary

with day and night.

The troposphere determines the weather

The stratosphere acts as a lid

Layer Extension Time scale

Boundary layerTroposphereStratosphere

Minutes to hoursDays to weeksYears

Ground - 100 m/3 km100 m/3 km - 10 m/15 km

10 m/15 km - 50 km

PLUMES SHAPES FROM A HIGH CHIMNEY FOR SEVERAL STABILITY CONDITIONS

Adiabatic T profiles as a function of altitude and the drawn curves the ‘real’profile for several cases

Behaviour of a parcel of air, reflected in the plume shape on the right

Sorgente emissiva puntuale e costanteSorgente emissiva puntuale e costante

Dispersion coefficients and as a funcion of the distance from the source for the atmospheric stability conditions.

Plume gaussiani da un camino Plume gaussiani da un camino altoalto

A livello del suolo :A livello del suolo : Lungo l’asse del plumeLungo l’asse del plumey = 0

Ground level concentration underneath the axis of a horizontal plume.

Here a = σy / σz

Determinazione diretta di sDeterminazione diretta di sy y e e sszz

Pasquil stability categories