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
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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
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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?
Vertical structure of the
atmosphere
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.
Composition of the atmosphere
• Variable gases
Distribution varies in
time and space
• Permanent gases
Forms a constant
proportion of the
atmosphere
Composition of the atmosphere – Permanent
Gases
• Nitrogen
– 75% of atmosphere
– Relatively
unimportant in
climatological and
meterological
processes
• Oxygen
– 21% of atmosphere
– Important for
respiration and
combustion
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).
• 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
Review…
Describe the
1. Structure of the atmosphere
2. Composition of the atmosphere