1. MADISON’S CURRENT WEATHER
Madison Weather at 1000 AM CDT
THU JUL
Updated twice an hour at :05 and :25
Sky/Weather: SUNNY
Temperature: 63 F (17 C)
Dew Point: 42 F (5 C)
Relative Humidity: 46%
Wind: N7 MPH
Barometer: 30.10S

2. Surface Weather Map from Today with Isobars & Fronts

3. Current Temperatures (oF) & Isotherms

4. Current Dewpoints (oF)

7. Tomorrow’s 7AM Forecast

8. Current UVI Forecast

9. Last 24 hrs in Madison

11. At Southern Lake Michigan Buoy

12. Announcements Homework 2 is due today.
Exam on Monday here end of class).
Study sheet is online.
Answers to Homeworks 1 & 2 to be posted.

13. ATM OCN 100 - Summer 2001 LECTURE 9
BEHAVIOR OF GASES in the ATMOSPHERE: Thermodynamics A. INTRODUCTION
How are pressure & temperature related?
Why are lows cloudy and highs fair?

14. B. KINETIC THEORY OF MATTER
Definitions
Historical
Assumptions for gases:
Tiny molecules with large space;
No attraction between molecules;
Random molecular motion;
Elastic molecular collisions.

15. B. KINETIC THEORY OF MATTER (con’t.)
Molecular Diffusion
Transport of fluid properties by molecular motion;
Direction is from high toward low concentration regions.

16. B. KINETIC THEORY OF MATTER (con’t.)
Variables describing molecular state of a gas
Density = molecular mass per volume
Temperature ~ average molecular speed
Pressure ~ molecular momentum change (~ molecular speed & mass)

17. C. THE GAS LAWS
Classical approach to Ideal Gas Law (or Equation of State)

18. Atmospheric application of Ideal Gas Law
If P = constant, then increases as T decreases;
If = constant, then P increases when T increases;
If T = constant, then increases as P increases.

19. Dalton's Laws of Partial Pressures Involves mixture of ideal gases;
C. THE GAS LAWS (con’t.)
Dalton's Laws of Partial Pressures
Involves mixture of ideal gases;
Each gas has own partial pressure, p(i).
Then: Total Pressure = Sum of partial pressures

20. C. THE GAS LAWS (con’t.)
Atmospheric Applications of Dalton's Laws of Partial Pressures
PTotal = p(N2) + p(O2) + p(Ar) + e + ...
Where p(N2), p(O2), p(Ar) are partial pressures of major atmospheric gases & e = (partial water) vapor pressure.
So for air with some moisture: PTotal = 1020 mb  ( ) mb e  (20 to 40 mb)

21. D. THE THERMODYNAMIC LAWS
Introduction
First Law of Thermodynamics
Input = Output + Storage

22. D. THE THERMODYNAMIC LAWS (con’t.)
Atmospheric application of First Law of Thermodynamics
Heat exchange = Work + Internal energy Change
Heat exchange by radiation, etc.;
Work by volume change;
Internal energy change by temperature change.

23. D. THE THERMODYNAMIC LAWS (con’t.)
Adiabatic Processes
No heat exchanged with environment; Work = internal energy change
Involves volume change only:
Volume change = Temperature change
Volume decrease (or Pressure increase) causes heating;
Volume increase (or Pressure decrease) causes cooling.

24. E. THE VERTICAL MOTION PROBLEM
Response of an air parcel
Rising motion: Encounters lower pressure Expansion & cooling
Sinking motion: Encounters higher pressure Compression & warming
Specification of the response

25. Response of Ascent/Descent of Air Parcel: Dry Adiabatic Lapse Rate (10C°/1000m) See Fig. 6.8 Moran & Morgan (1997)
P  600 mb, V= 1.44 m3
P  700 mb, V= 1.28 m3
P  800 mb, V= 1.16 m3
P  900 mb, V= 1.07 m3
T = 20C, P  1000 mb, V= 1.00 m3

26. E. VERTICAL MOTION (con’t.)
Specification of parcel response
describes cooling/heating by adiabatic expansion/compression process;
assume dry air parcel.
The dry adiabatic lapse rate (DALR)
Recall that lapse rate is how temperature decreases with height;
DALR  10 Co per 1000 meters or Fo per 1000 feet.

27. E. VERTICAL MOTION (con’t.)
Response of an air parcel
An example

28. U.S. STANDARD ATMOSPHERE See Fig. 1.9 Moran & Morgan (1997)
Thermosphere
Mesopause
Mesosphere
Stratopause
Stratosphere
Tropopause
Troposphere

29. GREEN BAY RADIOSONDE SOUNDING Sunday PM
GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

30. Why does the Hot Air Balloon Rise?

31. When Convection?

32. GREEN BAY RADIOSONDE SOUNDING Wednesday PM
GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

33. F. STATIC STABILITY
Importance
Stability-Instability Concept
Stable: Return to initial state
Unstable: Continuation away from initial state
Criteria for Static Stability (Instability) Determination

34. STABLE CONDITIONS Compare Environment with DALR Colder parcel sinks & returns to start

35. UNSTABLE CONDITIONS Compare Environment with DALR Warmer parcel continues upward

36. F. STATIC STABILITY (con’t.)
Processes which change static stability (instability)
Cool below, but warm above (stabilize)
Warm below, but cool above (destabilize)
Visual stability indicators

37. Example of Stabilization– An Inversion

38. Example of Destabilization-- Cumulonimbus

39. F. STATIC STABILITY (con’t.)
Processes which change static stability (instability)
Visual stability indicators
Graphical Analysis: The Thermodynamic Diagram

40. GREEN BAY RADIOSONDE SOUNDING Sunday PM
GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

41. GREEN BAY RADIOSONDE SOUNDING Wednesday PM
GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

42. GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

43. Current Temperatures (oF) – 24 Hrs Ago

44. U.S. STANDARD ATMOSPHERE See Fig. 1.9 Moran & Morgan (1997)
Thermosphere
Mesopause
Mesosphere
Stratopause
Stratosphere
Tropopause
Troposphere