© oxford university press, 2008. all rights reserved. 1 chapter 5 chapter 5 hydrologic systems and...

© Oxford University Press, 2008. All rights reserved.1

Chapter 5

CHAPTER 5

HYDROLOGIC SYSTEMS AND ATMOSPHERIC PROCESSES

© Oxford University Press, 2008. All rights reserved.1

Chapter 5

INTRODUCTION• Water is a unique substance• The hydrologic cycle

Precipitation

Evaporation

Transpiration

Sublimation

Runoff and infiltration

Changes of state of water

© Oxford University Press, 2008. All rights reserved.1

Chapter 5

MOISTURE IN THE ATMOSPHERE

• Latent heat of evaporation

• Defining saturation

• Spatial distribution in Australia

• Descriptions of atmospheric moisture– Relative humidity– Mixing ratio

© Oxford University Press, 2008. All rights reserved.1

Chapter 5

CLOUD FORMATION

• Formation requirements– Water vapour– Nucleation– Trigger mechanisms– Is cloud seeding effective to create rain?

© Oxford University Press, 2008. All rights reserved.1

Chapter 5

BASIC THERMODYNAMICS

• Definitions

• Lapse rates (dry, wet)

• The role of saturation

• Calculation of cloud location using T and Td

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Chapter 5

ESTIMATING ATMOSPHERIC STABILITY

• Adiabatic lapse rates versus background atmospheric temperature

• Estimating states of stability– Absolutely unstable– Conditionally unstable– Stable

• Inversions

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Chapter 5

TRIGGER MECHANISMS

• Convection

• Orographic

• Frontal

• Others

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Chapter 5

CLOUD DROPLET FORMATION AND GROWTH

• Condensation around nuclei• Collision/coalescence• Wake capture• The importance of convection and

turbulence• Identifying cloud types• Altocumulus lenticularis cloud formation

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Chapter 5

DEW AND FOG• Dew and frost formation

• Fog formation and types– Radiation– Advection– Steam– Upslope– Global frequency distribution– Fogwater as a resource

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Chapter 5

SYNOPTIC AND REGIONAL PRECIPITATION

• Fronts and frontal theory– Types of fronts– Lifecycle in Australia– The influence of upper tropospheric waves – Consequences

• Squall lines• Thunderstorms

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Chapter 5

THUNDERSTORMS AND THEIR HAZARDS

• Scale of thunderstorm systems• Initial formation• Mature stage• Old age• The role of the jet stream• Hazards

– Hail– Lightning– Downbursts and microbursts– Tornadoes

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Chapter 5

TORNADOES

• Definition

• Conditions for formation

• Spatial and seasonal distributions

• Fujita destruction scale

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Chapter 5

PRECIPITATION DISTRIBUTION

• Northern Australia

• Global