1. NATS 101 Lecture 3 Climate and 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

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

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

5. Sky Cover and Weather Symbols
Ahrens, p 431
Ahrens, p 431

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

7. SLP pressure
temperature dew point
cloud cover
Ohio State website
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?

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?

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

12. Radiosonde
Weather balloons, or radiosondes, sample atmospheric to 10 mb.
They measure temperature moisture pressure
They are tracked to get winds
Ahrens, Fig. 1

13. Radiosonde Distribution
Radiosondes released at 0000 and at 1200 GMT for a global network of stations.
Large gaps in network over oceans and in less affluent nations.
Stations ~400 km apart over North America

14. Radiosonde for Tucson
Example of data taken by weather balloon released over Tucson
Temperature (red)
Moisture (green)
Winds (white)
Note variations of all fields with height
UA Tucson 1200 RAOB
stratosphere
tropopause
troposphere
temperature profile
moisture profile
wind profile

15. 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)

18. Climate of Tucson Monthly Averages
Individual months can show significant deviations from long-term, monthly means.

19. Average and Record MAX and MIN Temperatures for Date

20. Climate of Tucson Probability of Last Freeze
Cool Site: Western Region Climate Center

21. Climate of Tucson Probability of Rain
Cool Site: Western Region Climate Center

22. Climate of Tucson Extreme Rainfall
Cool Site: Western Region Climate Center

23. Cool Site: Western Region Climate Center
Climate of Tucson Snow!
Cool Site: Western Region Climate Center

24. 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

25. Reading Assignment Ahrens Pages 25-30 Problems 2.1-2.4
(2.1  Chapter 2, Problem 1)
Don’t Forgot the 4”x 6” Index Cards…