ATM OCN 100

1
ATM OCN 100 Summer 2002 LECTURE 7

• ATMOSPHERIC ENERGETICS RADIATION (cont.)
• A. Introduction
• B. Radiant Energy - Fundamentals

2
Announcements

• Homework 1
• Please Pick up yours in front.
• Homework 2
• Get from our webpage
• http//www.aos.wisc.edu/hopkins/aos100/homework/
  
• Due Monday 1 Oct 2001

3
MADISONS CURRENT WEATHER
at 900 AM CDT WED SEP 26 2001 Updated twice an
hour at 05 and 25 Sky/Weather FAIR
Temperature 51 F (10 C) Dew Point 38 F (3
C) Relative Humidity 60 Wind NW10 MPH
Barometer 30.04F
4
Rules of Thumb

• Other things being equal
• Cloudy nights have higher temperatures than clear
  nights.
• Cloudy days have lower temperatures than clear
  days.

5
(No Transcript)
6
This mornings low temperatures (oF)
7
This Mornings Low Temperatures (oF) (1961-90)
Average Low Temperatures
8
Current Surface Weather Map with Isobars (iso
equal bar weight), Fronts and Radar
9
Tomorrow AMs Forecast
10
Yesterdays high temperatures (oF)
11
Yesterdays High Temperatures (oF) (1961-90)
Average High Temperatures
12
Surface Weather Map from Today with Isobars
Fronts
13
Current Temperatures (F) Isotherms
14
Landsat-7 Image of NW Wisconsin nr Siren 18 May
2001 (Pre tornado)http//www.news.wisc.edu/newsph
otos/siren.html
15
Landsat-7 Image of NW Wisconsin nr Siren 19 June
2001 (After tornado)http//www.news.wisc.edu/news
photos/siren.html
16
(No Transcript)
17
(No Transcript)
18
Surface Weather Map from Today with Isobars
Fronts
19
Current Temperatures (oF) Isotherms
20
Hurricanes Isaac Joyce
21
Yesterdays High Temperatures (oF) (1961-90)
Average High Temperatures
22
Tomorrows 7AM Forecast
23
Current Wind-Chill Equivalent Temperatures (oF)
24
ATM OCN 100 - Summer 2002 LECTURE 7

• ATMOSPHERIC ENERGETICS RADIATION
• A. INTRODUCTION
• What is radiation?
• What is significance of radiation?

25
B. RADIANT ENERGY orELECTROMAGNETIC RADIATION

• The nature of electromagnetic radiation
• Wave forms
• Terminology describing waves
• Speed of wave
• Wavelength Fig 2.2 Moran Morgan (1997)
• Frequency

26
WAVE TERMINOLOGY

• Speed of wave
• miles per hour or meters per second
• Wavelength
• meters or micrometers
• Frequency
• Cycles per second or Hertz

27
WAVE TERMINOLOGY (cont.)

• Fundamental Relationship
• Speed wavelength x frequency

28
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• The Electromagnetic Spectrum
• The entire spectrum
• Typical names
• X-Rays through Radio Waves
• Spectral regions important to meteorology
• UV, Visible, IR (also microwave)

29
The Electromagnetic SpectrumSee Fig. 2.1 Moran
Morgan (1997)
ROY G BIV
30
The Hazards of UV Radiation

• Region of concern
• UVA
• UVB
• Consequences of increased UV Radiation
• Skin Cancer
• Cataracts
• Changes in Genetic Pool
• The UV Index

31
(No Transcript)
32
The UV Index (UVI)

• Numerical Values
• Related to time needed to receive sunburn
• UVI 0-2 (Minimal) ? 60 minutes
• UVI gt 10 (Very High) lt 10 minutes
• UVI Values depend upon
• Latitude
• Elevation
• Clouds
• UVI forecasts produced daily by NWS

33
(No Transcript)
34
Current UVI Forecast
35
A June UVI Forecast
36
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Important relationships of radiation
• Ideal radiators/absorbers (black bodies)
• The ideal radiator curve
• Total amount of Energy emitted/absorbed
• Region of maximum radiation
  where ...

37
Electromagnetic Radiation Emission/Absorption as
a function of Temperature
38
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Total energy emitted/absorbed.
• (also known as Stefan-Boltzmanns Law)

39
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Region of maximum radiation.
• (also known as Wien's Displacement Law)

40
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Inverse Square Relationship
• Intensity of incident radiation varies inversely
  with square of distance from radiation source

41
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Inverse Square Relationship
• Intensity of incident radiation varies inversely
  with square of distance from radiation source

42
INVERSE SQUARE LAW (cont.)
43
INVERSE SQUARE LAW (cont.)
Earth
44
ELECTROMAGNETIC RADIATION FUNDAMENTALS (cont.)

• Zenith Angle Relationship
• Intensity of incoming radiation is
• greatest for vertically oriented rays
• least for rays that parallel horizontal surface.
• Intensity of incoming radiation is proportional
  to cosine of incident angle (defined as
  zenith angle)

45
COSINE ANGLE RELATIONSHIP (cont.)
46
Solar Altitude Angles at Different LatitudesFig.
2.6 Moran and Morgan (1997)
47
C. THE EARTH, THE SUN andTHE RADIATION LINK

• The Sun Solar radiation
• A star with surface temperature ? 6000 K
• Peak radiation ???????m.

48
Our Sun Space Environment Center
49
Our Sun from Yesterday Space Environment Center
H-Alpha Image
Helium Image
50
Sunspot NumbersFig 20.5 Moran Morgan (1997)
51
Extra-atmospheric Solar Radiation See Fig 2.3,
Moran Morgan (1997)
52
C. THE EARTH, THE SUN THE RADIATION LINK
(cont.)

• Receipt of solar radiation by Earth-atmosphere
  system
• Solar Constant Incoming solar radiation received
  on surface that is
• Perpendicular to suns rays
• Above atmosphere
• at mean earth-sun distance.
• Currently accepted value
• 2 cal/cm2/min 1370 Watt/m2.

53
INVERSE SQUARE LAW (cont.)
Earth
54
C. THE EARTH, THE SUN THE RADIATION LINK
(cont.)

• Our place in the Sun -- Annual diurnal
  motions of Earth
• Solstices equinoxes
• Local noon sunrise/sunset

55
Earths Orbit of Sun The Cause of the Seasons
See Fig. 2.10 Moran Morgan (1997)
56
Earths Orbit of Sun The Cause of the Seasons
See Fig. 2.10 Moran Morgan (1997)
57
DAYLIGHT-NIGHT (23 JUN)
58
DAYLIGHT-NIGHT (21 SEP)
59
DAYLIGHT-NIGHT (22 DEC)
60
Latitudinal Dependency
61
Solar Altitude Angles at Different LatitudesFig.
2.6 Moran and Morgan (1997)
62
Our Tilted Earth
63
Sun Paths for Mid LatitudesFig. 2.14 Moran and
Morgan (1997)
64
Diurnal Variation in Solar Altitude Angle at
Madison
65
C. THE EARTH, THE SUN THE RADIATION LINK
(cont.)

• Disposition of solar radiation in
  Earth-atmosphere system
• Reflected
• Scattered
• Absorbed
• Transmitted
• Albedo
• where...

66
ALBEDO

• The reflectivity of a surface
• Albedo of surfaces
• Implications

67
C. THE EARTH, THE SUN THE RADIATION LINK
(cont.)

• Terrestrial radiation
• Emitted from earth-atmosphere system
• Radiating temperature ????????
• Peak radiation region ??????m.

68
Terrestrial or Long Wave Radiation Emitted at 300
KSee Fig 2.4, Moran Morgan (1997)