welcome back, geographers!
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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
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