1. Earth’s Physical Environments
Lecture 1
Earth’s Physical Environments
Exogenetic fluvial processes: erosion, transportation and sedimentation
Courtesy: U.S. National park service

2. Objectives Define physical geography
Explain the reasons for studying physical geography
Explain how we study physical geography
Define models and describe their types
Describe the factors that complicate the study of pattern and process
Distinguish between proximate and ultimate causation
Define and give examples of positive and negative feedback
Give examples of how scale influence our understanding of pattern and process
Describe and give an example of how thresholds and time lags complicate the study of pattern and process
Explain how teleconnections complicate the interpretation of pattern and process
Describe the difference between steady state and dynamic equilibrium

3. What is Physical Geography?
It is the integrated study of three subdisciplines:
Climatology
Biogeography
Geomorphology
This course will provide a holistic and reductionistic understanding on physical geography.
Holistic and reductionist understanding
化約主義主要有三種意義：(1)主張任何複雜的現象都可由分析現象的基本物理結構來解釋；(2)極力簡化複雜的觀念、事件、狀態等，有低估、曲解且模糊事物真相之處；(3)試圖將某種科學簡化為另一種科學，將某種科學所使用的關鍵詞用另種科學的語言來予以定義，而其結論也可從另種科學的命題中導出。

4. What is Physical Geography?
2014 Oso (Washington) landslide
This is the Anthropocene, the period in time when humans have a substantial influence on the Earth
Mass movements are the result of natural and human processes. This is the 2014 Oso mudslide, which killed 43 people in Washington state. Logging of the uplands may have allowed groundwater to percolate into the steepened slopes, which had a history of instability. Heavy rains in the days before the slide were also a factor.

5. What is Physical Geography?
As in the anthropocene, it may also incorporate the way human shape climatic, biogeographic, and geomorphic phenomena.

6. Why study physical geography?
The natural world is as complex as the human world, if not more so
Consider these facets of the Earth’s surface
Its immense extent (size) and resolution (detail)
History and time since origin (4.5 billion years)

7. Why study physical geography?
To understand human-environment interactions, you need to understand how the non-human world works first.
If you want to study global warming, its not all politics, economics, history, and technology. You have to know how the atmosphere, weather, and climate work.

8. Why study physical geography?
To study global warming, you have to know how the atmosphere, weather and climate work first (It is not all politics, economics, history and technology).

9. How do we study physical geography?
We document pattern and process

11. Turf (草皮), bank terraces (堤岸 階地)

12. Erosion at base of terrace landform creates protected mineral soil needed by germinating (萌芽的) conifers.

13. We use models to study pattern and process
Models are a simplified, often idealized representation of reality.
A model intends to recreate patterns by capturing the underlying explanatory processes
While studying models, you should recognize that they are idealized and try to identify why they are incomplete.

14. What are the types of models?
Graphical conceptual models
Citation: Alpine Treeline of Western North America: Linking Organism-To-Landscape Dynamics
Sieve濾器
Alpine:高山
Ecotone: a region where one type of habitat or natural environment meets another生態過渡帶
Dispersal:分散
Germination:發芽
Propagule:繁殖
krummholz:高山矮曲林
Upright: 直立
Seedling:幼苗
Citation: Malanson et al. 2007: Alpine Treeline of Western North America: Linking Organism-To-Landscape Dynamics

15. Types of models
Maps

16. Types of models Dynamical models
Use field-derived conditions to model the behavior of a phenomena
Can be used to predict or forecast the future
Predicted tracks of “Superstorm” Sandy

17. Types of models
Dynamical models can also be used to hindcast the past and study events that have already happened
Honshu本州

18. Types of models Simulations Mathematically-based
Can be given visual form, i.e., animated
Has no actual counterpart in the real world, i.e. observational data is not what drives the simulation

19. Types of models Statistical models
Use the record of the past to predict the future

20. Types of models Physical models
Employ a scale-down physical version of real-world processes

21. What complicates the study of pattern and process?

22. 1. Multiple driving variables
Driving variables are most directly responsible for the observed patterns.
Driving variables are not always readily apparent or easily distinguished from other variables
driving variables are nevertheless physically consistent.
These factors shown shape weather and climate as well as vegetation. If you were studying the distribution of a tree species, river discharge, or weather patterns, many of these factors would be at play, some more than others.

23. Proximate and ultimate causation
A proximate cause is an event which is closest, or immediately responsible, for causing some observed result.
This exists in contrast to a higher-level ultimate cause which is usually thought of as the "real" reason something occurred.
Procimate: the direct cause
Why are you here today, in class?
Registered for this class versus my mom and dad meeting
Requirements for graduation versus evolution of humans in Africa What causes the patterns of dune vegetation?
Proximate cause: local patterns of sediment movement and how dune plant species respond to it
Ultimate cause: dispersal of seeds and establishment of plants that can trap sediment

24. Why did the ship hit the rock?
Proximate cause: Because the ship failed to change course to avoid it.
Ultimate cause: Because the ship was under autopilot and the autopilot received bad data from the GPS.
Separating proximate from ultimate causations frequently leads to better understandings of multiple driving variables
So, not useful to always say we have the same history – we evolved out of the primordial soup. Nor is it useful to think of only the most recent cause. We have to disregard some patterns and choose others to look at.

25. 2. Contingent events
What contingencies complicate the prediction of wildfires?
Contingent:隊伍
What are the more predictable variables related to when and where wildfires occur? What are the more contingent variables?

26. 3. Feedbacks
Feedbacks make prediction of the outcome of interactions difficult
Positive feedback: externally generated change is reinforced
Negative feedback: externally generated change is minimized

27. Example of positive and negative feedbacks associated with global warming

28. Permafrost Thermokarst lakes
Thermokarst (热融喀斯特) lakes have positive and negative feedbacks associated with global warming.
Thermokarst lakes

29. Melting of karst forms thermokarst lakes
Melting of karst forms thermokarst lakes. Warmer temperatures that cause melting also increase the decomposition of plant matter in previously frozen soils. This releases methane, a greenhouse gas.
Runoff from the land into the lakes brings nutrients that increase the biological productivity of the lake water – photosynthetic unicellular organisms begin to grow and photosynthesize and thus take up carbon dioxide, a greenhouse gas.

30. Sediments begin to accumulate in the bottom of the lake
Sediments begin to accumulate in the bottom of the lake. These sediments contain carbon- containing plant matter. This plant matter will degrade less, and slow the release of methane, a greenhouse gas
If a wetland forms, the plants that comprise it will take up carbon dioxide, a greenhouse gas

31. Arctic's melting permafrost
Image: REUTERS/Dmitry Solovyov

32. 4. Spatial and temporal scales
Scale determines how we understand pattern and process
Example: controls on temperature: what makes it warm or cold?
Different scales may also interact together.

33. Answer depends upon temporal and spatial scale
Cloud cover and humidity (minutes to hours)
Diurnal (day-night) cycles
Seasonal cycles (1 year)
Cyclical fluctuations due to sunspots (10-50 years)
Anthropogenic contribution of greenhouse gases ( years)
Milankovitch orbital cycles (10,000 yrs)

36. Wet Drought index Dry Wet Drought index Dry
How does scale apply to the interpretation of these graphs? The western US was settled during the last 200 years. What can you tell me about the climate over that period? Was it wetter or drier than what the record shows over the last 400 years?
Dry

37. Wet Drought index Dry Wet Drought index Dry
The long periods of drought that occurred in the past are called megadroughts. They lasted in some cases for a century. It is possible that these dry periods can return. The western US was settled during a wet period.
Drought index
Dry

38. 5. Thresholds and time lags
Melting of Greenland ice sheet

41. 6. Teleconnections

42. Global monthly temperatures illustrating the effect of the June 1991 volcanic eruption of Mount Pinatubo in the Philippines. The temperature effect apparently lasted to the end of 1992, as indicated by the shaded area.

43. 7. The earth is constantly changing
Earth is an open system
Change is the norm
Change itself, however, has different types
Steady state equilibrium
Dynamic equilibrium

44. Steady state equilibrium
Inputs = outputs, balance achieved. Same value maintained. In a steady state the level of the water stays the same.

45. Dynamic equilibrium
Constantly changing

47. End of Lecture 1