1. WAVELENGTHS ARE MEASURED FROM ONE CREST TO THE NEXT

2. RADIATION
Radiation is he emanation of any part of the electromagnetic spectrum plus the release of particles

8. Where does the sun appear in the sky in summer and winter?

9. WHY WE HAVE SEASONS

12. The radiative properties of the material (most are selective in the wavelengths they absorb.
2. The amount of time the object is exposed to the emitted energy. The longer it is exposed the more energy it can absorb
3. The amount of the material. Very think objects may transmit and not absorb all the energy reaching them. Increasing thickness can increase the amount of energy it can absorb
4. How close the object is to the source of the energy. The further away, the less radiation reaches it. The less energy that reaches it the less it can absorb.
5. The angle at which the radiation is striking the object. Direct radiation is more concentrated than oblique and is absorbed more effectively
A good absorber of radiation is also a good emitter of radiation at that same wavelength

13. EXAMPLES OF SOME ALBEDOS
 Fresh snow
Thin cloud 30
Thick cloud 90
Ice
Grass
Water 10
Forest
Venus 78

16. STEFAN BOLTZMANN LAW
E=σT4
E= maximum rate of radiation emitted by each square meter of surface area
σ (sigma) is the Stefan Boltzman constant (2897 μmK – rounded to 3000 μmK)
T=temperature in Kelvin to the 4th power
A small increase in temperature yields a large increase in radiation since the temperature is raised to the 4th power. So a temperature increase of just 2 degrees increase the energy output by a factor of 16 (24)

17. Wien’s Law (or Wien’s Displacement Law)
Wilhelm Wien, a German physicist showed that the wavelength at which the maximum radiation occurs is equal to Stefan Boltzman’s constant divided by the temperature in Kelvin
λmax = constant/T in degrees Kelvin
For the Sun:
The sun’s surface temperature is about 6000K so we get
λmax=3000 μmK/ 6000K = .5μm (the wavelength where maximum radiation occurs)
For the Earth:
The Earth’s average surface temperature is about 300K (actually 288)
λmax= 3000 μmK/ 300K = 10 μm (the wavelength where maximum radiation occurs)

20. Wear hat and apply SPF 15 sunscreen
Exposure Category
UV Index
Protective Measures
Minimal
0 – 2
Apply SPF* 15 Sunscreen
Low
3 – 4
Wear hat and apply SPF 15 sunscreen
Moderate
5 - 6
Wear hat, protective clothing and sunglasses with UV-A and UV-B protection. Apply SPF 15+ sunscreen
High
7 - 9
Wear hat, protective clothing and sunglasses. Stay in shady area Apply SPF 15+ sunscreen
Very High 10
Wear hat, protective clothing, sunglasses, apply SPF 15+ sunscreen avoid being in the sun between 10 A.M. and 4 P.M.
* sun protective factor

21. UV--------visible---------------------------------------------------Infrared

24. Atmospheric window is between 8 μm and 11 μm

25. EARTH’S ENERGY BUDGET Starting with 100 units of short wave radiation
30% is reflected and scattered back into space This is the Albedo
20% is absorbed by atmosphere and clouds
50% is absorbed by the earth
100 units arrived
50 units gained by earth
The Earth gives off LONG WAVE radiation
7 units go into the atmosphere in convection
23 units lost by evaporation (latent heat)
20 unit net loss from 114 unit radiated to atmosphere with 8 absorbed to the atmosphere 94 reflected back and 12 units reflected back to space making a total of 20 units lost
TOTAL 50 units radiated from Earth
BUDGET BALANCED
BUT WHERE ARE THE OTHER 50 units?
30 units are reflected by the atmosphere
The ATMOSPHERE
receives
20 units from the clouds
7 from convection
23 from condensation
8 units from the Earth (114 units radiated, 94 reflected back = 20; 12 go directly into space) = 8
TOTAL = 58 gotten
LOSS
Reflected 30 units from the sun
20 units absorbed by clouds
7 absorbed from convection
23 gotten from condensation
8 from earth radiation
58 units radiated back to space
TOTAL ARRIVING 100
TOTAL LEAVING 100
EARTH’S ENERGY BUDGET

26. ATMOSPHERE== SURFACE==
The 104 LW units from the surface is absorbed by the atmosphere and heats producing more LW units. The remaining 4 units are lost to space.
The atmosphere emits 154 LW units; 66 of which head to space while 88 head back to the surface.
The result is that the surface loses more than it gains (54 units) while the atmosphere also loses more than it gains (16 units) . This is an infinite cycle so the 88 units is radiated again reheating the air and retuning to earth and so on
The balance (or lack) of long wave radiation between the surface, the atmosphere and space.

28. ==SPACE ==ATMOSPHERE ==SURFACE SPACE== ATMOSPHERE== SURFACE==
The 104 LW units from the surface is absorbed by the atmosphere and heats producing more LW units. The remaining 4 units are lost to space.
The atmosphere emits 154 LW units; 66 of which head to space while 88 head back to the surface. The result is that the surface loses more than it gains (54 units) while the atmosphere also loses more than it gains (16 units) It is the absorption of the outgoing longwave radiation by the atmosphere that keeps the temperature where it is. If they were not there the temperature would vacillate wildly between day and night. The mean temperature on the Earth would be close to -18 C (0 F) than it is now, with the average temperature of 15 C (59 F)
LOGWAVE SURFACE Energy is exchanged between the atmosphere and the surface of the planet. The greatest part of the emission is absorbed by the atmosphere which is better at absorbing thermal radiation than solar because of the water ad CO2 in the atmosphere. Even so a portion passes out in the μm band which matches those radiated with the greatest intensity from the Earth.. The is called the ATMOSPHERIC WINDOW which is that part of electromagnetic spectrum that the atmosphere doesn’t absorb. CLOUDS however will absorb the long wave radiation hence CLOUDY NIGHTS DO NOT COOL OFF AS RAPIDLY AS CLEAR NIGHTS. THE CLOUDS ACT AS A BLANKET HELPING TO RETAIN HEAT

29. Some variation exists in examples depending on where and when the readings are taken

31. The 117 radiated by the Earth is larger than expected because the Earth radiates energy for both sides of the globe (i.e. the day and night side) whereas the solar energy only strikes the side facing the sun.
It gets 51 from the sun, but radiates 147. The 96 units comes from the infra-red returned to the earth from the atmosphere from sun = 147.
117-96= 21 (infra red radiated – the 96 returning from the atmosphere
So =51 – the amount arriving from the sun
It is the returning energy that warms the earth and keeps the temperature livable
If the amount of CO2 and water vapor increase, the amount returning becomes greater and the average temperature rises. (Climate change or global warming)

32. The 117 radiated by the Earth is larger than expected because the Earth radiates energy for both sides of the globe (i.e. the day and night side) whereas the solar energy only strikes the side facing the sun.
It gets 51 from the sun, but radiates 147. The 96 units comes from the infra-red returned to the earth from the atmosphere from sun = 147.
117-96= 21 (infra red radiated – the 96 returning from the atmosphere
So =51 – the amount arriving from the sun
It is the returning energy that warms the earth and keeps the temperature livable
If the amount of CO2 and water vapor increase, the amount returning becomes greater and the average temperature rises. (Climate change or global warming)