Welcome back, geographers!

Lecture 1- Agenda

• Expectations for 2009• Timeline for 2009• Introduction on new topic –

Atmospheric Processes, Hazards and Management

• Video Screening• Structure and composition of the

atmosphere

Expectations for 2009• Lectures• Do not be late• Make sure you have the relevant notes with you• Read up before the lecture, so that you can maximise

lecture time!• Clarify should you have any doubts

• Lecture Arrangement:• Monday Lecture Ms Yeo – Physical Geog 9730/01• Tuesday additional lecture Ms Yeo – Physical

Geo9730/01. TIME: 4.10-5.10. Venue:

Tutorial arragement

Tutorials• Do not be late• Make sure that relevant tutorials are done • Prepare questions to ask in class.

Files

• Geog reps (to be appointed during tuts) to buy ring files for the class.

• Buy the following:– 1 PURPLE ring file per student– 1 set of dividers (4 colours)

Weekly reflections

– You will be asked to reflect on your learning every week. Template will be given.

– Will be checked by tutors. – This acts as a mean to check your own

understanding and learning.

CMap

• I will be introducing a concept mapping tool which will help you in:

– Seeing big ideas of a topic– Revision of topics and sub-topics. – Sharing of concept map online which

allows resources to be shared. (and work to be given)

– MORE on CMap later.

Introduction to Atmospheric

Processes, Hazards and Management 4 sections: The Earth's Atmosphere and

Atmospheric Processes

2. Climatic zones of tropical Africa and

Asia

3. Adverse Weather Conditions

4. Climate Change and Responses

Concept Map of this topic

Section 1: Structure and Composition of atmosphere

At the end of this section, you should be able to:

1. Describe the structure and composition of the atmosphere.

Atmosphere- Definition

• Mixture of gas molecules,

• Microscopically small suspended particles of solid, liquid and falling

precipitation.

Vertical structure of the atmosphere

• Made up of various layers

Vertical structure of the atmosphere

Question:

Which layer does modern aircraft fly at?

1. Troposphere- Lowest layer- Where most weather processes take

place- Thermal structure: fall in temperature

with height. This fall continues until tropopause.

Why? Further from Earth's surface, lower contact with heat from Earth's surface.

Vertical structure of the atmosphere

2. Stratosphere• Lacks dust and water vapour• Relatively thin• Modern aircrafts fly at altitudes of lower

stratosphere.• Presence of ozone – Why is ozone important?• Thermal structure: increase in temp with height.

Why??? Ozone molecules absorb solar radiation.

Vertical structure of the atmosphere

3. Mesosphere and above

• About 50km from sea level

• Above 90km thermosphere (almost vacuum)

• Thermal structure: Temp falls with height – Why? Decreasing density of atmosphere

inability to absorb energy.

Vertical structure of the atmosphere

Composition of the atmosphere

• Variable gases

Distribution varies in time and space

• Permanent gases

Forms a constant proportion of the atmosphere

• Nitrogen – 75% of atmosphere– Relatively

unimportant in climatological and meterological processes

• Oxygen– 21% of atmosphere– Important for

respiration and combustion

Composition of the atmosphere – Permanent Gases

• Water vapour– Most variable spatially.– In humid tropics 4%– Over poles 1%

• Carbon dioxide– Present in small quantities– HIGHLY SIGNIFICANT in

meteorology– Fuelled discussion on global

warming

Composition of the atmosphere – Variable Gases

• Ozone (O3)

– Stratospheric O3 absorbs UV radiation from sun

– Tropospheric O3 is a greenhouse gas

– Also featured in discussion on climate change due to thinning of ozone layer over the Antarctica.

– Its depletion is due to extensive use of chlorofluorocarbons (CFCs).

Review…

Describe the

1. Structure of the atmosphere

2. Composition of the atmosphere