1. Weather, Climate & Society ATMO 336 Climate vs. Weather

2. “Climate is what you expect. Weather is what you get.”
Climate and Weather
“Climate is what you expect.
Weather is what you get.”
-Robert A. Heinlein
Lecture 2-Nats 101

3. Weather Weather – The state of the atmosphere: for a specific place
at a particular time
Weather Elements
1) Temperature
2) Pressure
3) Humidity
4) Wind
5) Visibility
6) Clouds
7) Significant Weather
Lecture 2-Nats 101

4. Responsible for boxed parameters
Surface Station Model
Responsible for boxed parameters
Temperatures
Plotted F in U.S.
Sea Level Pressure
Leading 10 or 9 is not plotted
Examples:
plotted as 138
998.7 plotted as 987
plotted as 360
Ahrens, p 431
Lecture 2-Nats 101

5. Sky Cover and Weather Symbols
Ahrens, p 431
Ahrens, p 431
Lecture 2-Nats 101

6. Wind Barbs Direction Wind is going towards Westerly  from the West
Speed (accumulated)
Each flag is 50 knots
Each full barb is 10 knots
Each half barb is 5 knots
65 kts from west
Ahrens, p 432
Lecture 2-Nats 101

7. Ohio State website SLP pressure temperature dew point cloud cover wind
Lecture 2-Nats 101
wind

8. Practice Surface Station
Temperate (oF)
Pressure (mb) Last Three Digits (tens, ones, tenths)
Dew Point (later) Moisture
Wind Barb Direction and Speed
Cloud Cover Tenths total coverage
Ahrens, p 431 72 58
111
Decimal point
What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?
Lecture 2-Nats 101

9. Practice Surface Station
Sea Level Pressure
Leading 10 or 9 is not plotted
Examples:
plotted as 138
998.7 plotted as 987
plotted as 360
Ahrens, p 431 42 18
998
Decimal point
What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?
Lecture 2-Nats 101

10. Surface Map Symbols Fronts
Mark the boundary between different air masses…later
Significant weather occurs near fronts
Current US Map
Ahrens, p 432
Lecture 2-Nats 101

11. Responsible for boxed parameters
Upper-Air Model
Responsible for boxed parameters
Conditions at specific pressure level
Wind
Temperature (C)
Moisture (Later)
Height above MSL
UA 500mb Analysis
Ahrens, p 431
Ahrens, p 427
Lecture 2-Nats 101

12. Climate
Climate - Average weather and range of weather, computed over many years.
Whole year (mean annual precipitation for Tucson, 1970-present)
Season (Winter: Dec-Jan-Feb)
Month (January rainfall in Tucson)
Date (Average, record high and low temperatures for Jan 1 in Tucson)
Lecture 2-Nats 101

13. Lecture 2-Nats 101

14. Lecture 2-Nats 101

15. Climate of Tucson Monthly Averages
Individual months can show significant deviations from long-term, monthly means.
Lecture 2-Nats 101

16. Lecture 2-Nats 101

17. Climate of Tucson Probability of Rain
Lecture 2-Nats 101
Cool Site: Western Region Climate Center

18. Climate of Tucson Extreme Rainfall
Lecture 2-Nats 101
Cool Site: Western Region Climate Center

19. Cool Site: Western Region Climate Center
Climate of Tucson Snow!
Lecture 2-Nats 101
Cool Site: Western Region Climate Center

20. Summary Weather - atmospheric conditions at specific time and place
Weather Maps  Instantaneous Values
Climate - average weather and the range of extremes compiled over many years
Statistical Quantities  Expected Values
Lecture 2-Nats 101

21. Weather, Climate & Society ATMO 325 Global Energy Balance Greenhouse Effect

22. General Laws of Radiation
All objects above 0 K emit radiant energy
Hotter objects radiate more energy per unit area than colder objects Stefan-Boltzman Law
The hotter the radiating body, the shorter the wavelength of maximum radiation Wien’s Displacement Law
Objects that are good absorbers of radiation are also good emitters
Lecture 2-Nats 101

23. General Laws of Radiation
Wien’s Displacement Law
Stefan-Boltzman Law
Lecture 2-Nats 101

24. Sun - Earth Radiation Spectra
Ahrens, Fig. 2.8
Planck’s Law
Lecture 2-Nats 101

25. Absorption Visible (0.4-0.7 m) is absorbed very littleIR
Visible ( m) is absorbed very little
O2 an O3 absorb UV (shorter than 0.3 m)
Infrared (5-25 m) is selectively absorbed
H2O & CO2 are strong absorbers of IR
Little absorption of IR around 10 m
Ahrens, Fig. 2.9
Lecture 2-Nats 101

26. Total Atmospheric Absorption
Ahrens, Fig. 2.9
Visible radiation ( m) is not absorbed
Infrared radiation (5-25 m) is selectively absorbed, but there is an emission window at 10 m
Lecture 2-Nats 101

27. 1 Unit Outgoing IR to Space 2 Units IR Emitted by Ground
Greenhouse Effect: Simple Example (1-layer atmo., 100% IR, 0% SR absorbed)
Balance
1 Unit Outgoing IR to Space
1 Unit Incoming Solar
1/2
1/4
1/8
1/16
½ emitted to space
½ emitted to ground
no SR absorbed
all IR absorbed
All SR +IR absorbed 1
1/2
1/4
1/8
1/16
2 Units IR Emitted by Ground
Net effect is 1 extra unit absorbed by the ground!
Lecture 2-Nats 101

28. Global Solar Radiation Balance
70% solar absorbed by earth-atmosphere
Ahrens, Fig. 2.13
Lecture 2-Nats 101

29. The Atmosphere is Heated from Below
Ahrens, Fig old ed.
Lecture 2-Nats 101

30. Global Atmo Energy Balance
Ahrens, Fig. 2.14
Lecture 2-Nats 101

31. Summary Greenhouse Effect (It’s a Misnomer) Energy Balance
Warmer than Rad. Equilibrium Temp
Reason: selective absorption of air
H2O and CO2 most absorbent of IR
Energy Balance
Complex system
All modes of Heat Transfer are important
Lecture 2-Nats 101