What is precipitation?What is precipitation?

• Phases of water in the air

• Cloud formation

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PRECIPITATION AND CLOUDSPRECIPITATION AND CLOUDS

What is precipitation?What is precipitation?

Precipitation is part of the water cycle, where water vapour in the atmosphere returns to a solid or liquid state and falls to the Earth.

Precipitation includes things like rain, snow and hail.

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evaporation

condensation

precipitationconvection

waterwatervapour

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Precipitation processesPrecipitation processes

Most temperate-zone precipitation starts off as snow!

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Where does our rain originate?

Water vapour is transported and concentrated in the atmosphere by vertical and horizontal motion

evaporation

convection

advection

precipitation

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Water vapour transportWater vapour transport

VapourInvisible but detectableWater in a gaseous stateVapour/steam

DropletsVisible as rainForm when air becomes saturated via the process of condensation

Ice particlesAt temperatures below 0°CHail often found at warmer ground surface temperatures

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Phases of water in the airPhases of water in the air

Ice particlesIce particles

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Wellington fog

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Cumulus cloudsEdward Hyde

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Clouds at Cape Hallett, Antarctica

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cold cloudspart/all above 0°C isotherm

ice droplets

Clouds are mixtures of droplets and ice particles

0°C isotherm

warm cloudstemp. > 0°C

droplets

glaciated cloudstemp. < –40°C

ice

mixed clouds

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CloudsClouds

Cumulonimbus – a mixed cloudPhilip Norton

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Cirrus – glaciated cloudsEdward Hyde

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