Elements of the Sun; Solar Radiation

1
Lecture 2 Weather and Climate

• Ch. 1 (p.1-16)
• Weather and climate
• Earth history
• Time scales of climate change
• Development of climate science
• Components of the climate system
• Forcing and response
• Response times

2
Weather versus Climate
Weather
The condition of atmosphere at a given time and
place

• Short-term (and large) fluctuations that arise
  from internal instabilities
• of the atmosphere

• Occurs as a wide variety of phenomena that we
  often experience

• Effects are immediately felt

• Social and economic impacts are great but are
  usually localized

• Many such phenomena occur as part of
  larger-scale organized systems

• Governed by non-linear chaotic dynamics not
  predictable
• deterministically beyond a week or two

3
Low Pressure High Pressure
Anti-Cyclonic Turning divergence leads to
downward vertical motions.
Cyclonic Turning Convergence leads to upward
vertical motions.
Cold Air
Warm Air
4
Impacts of Weather
5
Impacts of Weather
6
Impacts of Weather
7
Impacts of Weather
8
Weather versus Climate
Climate

• Defined as the average state of the atmosphere
  over a finite time
• period and over a geographic region (space).

• Can be thought of as the prevailing weather,
  which includes the
• mean but also the range of variations

• The wide range of natural variability associated
  with daily weather
• means small climate changes are difficult to
  detect

• Intimate link between weather and climate
  provides a basis for
• understanding how weather events might change
  under a
• changing climate

• Climate is what you expect and weather is what
  you get.

• Climate tells what clothes to buy, but weather
  tells you what clothes to wear.

9
Climate versus Weather
Climate

• Defined as the average state of the atmosphere
  over a finite time
• period and over a geographic region (space).

• Can be thought of as the prevailing weather,
  which includes the
• mean but also the range of variations

• The wide range of natural variability associated
  with daily weather
• means small climate changes are difficult to
  detect

• Intimate link between weather and climate
  provides a basis for
• understanding how weather events might change
  under a
• changing climate

• Involves atmospheric interactions with other
  parts of the climate
• system and external forcing

• Climate prediction is complicated by considering
  the complex
• interactions between, as well as changes
  within, all components

10
Koppen's Worldwide Distribution of Climatic
Regions, I
11
Koppen's Worldwide Distribution of Climatic
Regions, II
12
Review Questions

• Which of the following statements relate more to
  weather (A) and which relate more to climate (B)?
• 1. The summers in Austin are hot and humid.
• 2. It is 75F right now, partly sunny, and south
  winds 10 to 20 miles per hour.
• 3. September 2001 was the 2nd coolest September
  of record for Austin/Bergstrom International
  Airport.
• 4. Although winters in Austin are on the average
  mild by U.S. standards, cold outbreaks sometimes
  come, in some years more frequent than in others.
  These cold outbreaks are sometimes preceded or
  followed by periods of summerlike weather.
• 5. The pressure now is 29.75 inches and steady,
  and humidity is 84.

13
Review Questions

• Which of the following statements relate more to
  weather (A) and which relate more to climate (B)?
• B 1. The summers in Austin are hot and humid.
• A 2. It is 75F right now, partly sunny, and
  south winds 10 to 20 miles per hour.
• B 3. September 2001 was the 2nd coolest September
  of record for Austin/Bergstrom International
  Airport.
• B 4. Although winters in Austin are on the
  average mild by U.S. standards, cold outbreaks
  sometimes come, in some years more frequent than
  in others. These cold outbreaks are sometimes
  preceded or followed by periods of summerlike
  weather.
• A 5. The pressure now is 29.75 inches and steady,
  and humidity is 84.

14
Earth History
Earths age 4.55 billion years (Byr)
4,550,000,000 years 4.55 109 years This
book focuses on only recent 10 of its age.
15
Time Scales of Climate Change
Earths climate changes all the time, e.g., last
300 Myr, last 3 Myr, last 50,000 yr, and last
1000 yr.
Hockey Stick
16
Development of Climate Science
19th century early 20th century isolated
studies. Middle 20th century 1980s rapid
development into a mature science. In the past
two decades earth system approach. Multidiscipli
nary interdisciplinary.
How scientists study climate change
Observations ? ?Theory
You produce junk and waste a lot of money
Your tools are terribly antiquated and imprecise
Climate Modeler
Field-Geologist
17
Components of the Climate System
Five major components air (atmosphere), water
(hydrosphere), ice (cryosphere), vegetation
(biosphere), and land (lithosphere). Major
processes energy cycle, water cycle, carbon
cycle,
18
The Climate System Components
19
Climate System Components

• Atmosphere
• Fastest changing and most responsive component
• Previously considered the only changing
  component

• Ocean
• The other fluid component covering 70 of the
  surface
• Plays a central role through its motions and
  heat capacity
• Interacts with the atmosphere on days to
  thousands of years

• Cryosphere
• Includes land snow, sea ice, ice sheets, and
  mountain glaciers
• Largest reservoir of fresh water
• High reflectivity and low thermal conductivity

• Land and its biomass
• Slowly changing extent and position of
  continents
• Faster changing characteristics of lakes,
  streams, soil moisture
• and vegetation

• Human interaction
• agriculture, urbanization, industry, pollution,
  etc.

20
Climate An Engineers View
Input
Machine
Output
21
Forcing and Response A Bunsen Burner Experiment

• Three major kinds of climate forcing in nature
• Tectonic processes
• Earth-orbital changes
• Changes in Suns strength
• Anthropogenic forcing
• Urbanization
• Deforestation
• Burning fossil fuels
• Agriculture

Response time depends on materials or
components.
22
Response Times of Various Climate System
Components