MADISON’S CURRENT WEATHER Madison Weather at 1000 AM CDT THU JUL 5 2001 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

Surface Weather Map from Today with Isobars & Fronts

Current Temperatures (oF) & Isotherms

Current Dewpoints (oF)

Tomorrow’s 7AM Forecast

Current UVI Forecast

Last 24 hrs in Madison

At Southern Lake Michigan Buoy

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

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?

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. http://www.bcpl.net/~kdrews/kmt.html#List

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

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)

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

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.

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). http://psb.usu.edu/courses/bmet2000/humidity.html Then: Total Pressure = Sum of partial pressures

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  (780 + 210 + 9) mb + e  (20 to 40 mb)

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

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.

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.

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

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

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 5.5 Fo per 1000 feet.

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

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

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

Why does the Hot Air Balloon Rise?

When Convection?

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

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

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

UNSTABLE CONDITIONS Compare Environment with DALR Warmer parcel continues upward

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

Example of Stabilization– An Inversion

Example of Destabilization-- Cumulonimbus

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

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

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

GREEN BAY RADIOSONDE SOUNDING FRIDAY AM

Current Temperatures (oF) – 24 Hrs Ago

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