1. Insolation

2. Objective TSWBAT: Explain the factors affecting insolation
Explain the relationship between temperature and insolation
Describe evidence for Earth’s radiative balance
Define insolation, radiative balance
Describe the four ways the atmosphere is heated.

3. What could cause us to have different amounts of sunlight/insolation?

4. 1. Angle 90o (direct rays) most intense insolation
< 90o (less direct rays) least intense insolation

6. Angle and Temperature 90o = higher temperature
low angles = lower temperatures

7. 2. Earth’s Shape
If the Earth was flat, the angles would all be 90o (high temperatures)
The Earth is curved, so we get angles from 0o to 90o (range of temperatures)

10. 3. Latitude Fall/Spring – Equinox (March 21st and Sept 23rd)
Perpendicular (90°) at the Equator (0°)
Angle of incidence decreases as latitude increases (lowest at the North Pole (90°N) and South Pole (90°S))
12 hours of daylight everywhere
Altitude of noon sun: 47°
Not tilted toward/away from sun
Sunrise/set - E W

11. Fall/spring

12. Summer Solstice (June 21st)
Perpendicular (90°) at the tropic of cancer (23 ½ °N)
12 hours of daylight at equator (0°)
15 hours of daylight 43°N (Cambridge)
24 hours of daylight 90°N
9 hours of daylight at 40°S
0 hours of daylight at 90°S
Altitude of noon sun: 70.5°
Tilted toward the sun
Sunrise/set - NE NW

13. Summer Solstice

14. Winter Solstice Dec 21st
Perpendicular (90°) at the tropic of Capricorn (23 ½ °S)
12 hours of daylight at equator (0°)
9 hours of daylight 43°N (Cambridge)
0hours of daylight 90°N
15 hours of daylight at 40°S
24 hours of daylight at 90°S
Altitude of noon sun: 23 ½ °
Tilted away from the sun
Sunrise/set - SE SW

15. Winter Solstice

16. 4. Seasons Changes angles for latitudes
NY: Summer 70o, Fall/Spring 47o, Winter 23 ½ o

18. 5. Time of Day Sunrise and sunset have low angles (lower temperatures)
Noon has the highest angle
We (NY) never get a 90o angle at noon

21. So, if you have a greater angle of insolation, what happens to intensity and temperature?
Intensity will increase and temperature will increase

23. 6. Tilt of Axis
If there was no tilt, there would be no change in the seasons.
The angles would stay the same, similar to Fall/Spring.

24. 7. Parallelism of Axis Helps to change the angles for the latitudes
It makes the axis tilt toward the sun or away from the sun as it revolves around the sun

25. 8. Revolution Same as Parallelism of Axis and Seasons
Changes the angles for the latitudes

26. 9. Rotation Causes the angles to change during the day
Refer to Time of Day

28. Duration of Insolation
Means number of daylight hours
If the angle of insolation is low, there is a small duration of insolation (low temperatures)
Creates unequal distribution of heat
Why does this happen?
Tilted axis of rotation – greater amounts of insolation in the summer (northern hemisphere), less during the winter

29. Duration of insolation
NY: Winter: 23 ½ o, 8 hours of daylight, low temperatures, Dec 21st
Summer: 70o, 15 hours of daylight, high temperatures, high angle, high intensity
Fall/Spring - 47o hours of daylight.

30. Radiative balance
A condition in which a body gives off as much heat as it receives.
Insolation from Sun = infrared energy from Earth

31. Evidence for radiative balance: daily

34. Evidence of Radiative balance
1. Hottest and coolest times of day (4pm (maximum radiative energy) and 6am(minimum radiative energy))
2. Hottest and coolest times of year (July/Aug (maximum radiative energy) and Jan/Feb (minimum radiative energy))

35. Is Earth really in radiative balance?
Radiative balance means insolation = re-radiation.
Over long periods of time, Earth is in radiative balance.
Temperatures taken year to year vary though (short periods).

36. Heating the atmosphere
Direct absorption of radiation from the sun
Re-radiation of long-wave radiation from earth’s surface
Conduction
Latent heat of condensation

37. 1. Direct absorption of radiation from the sun
Gases absorb long-wave and short-wave radiation
Transferred into heat energy

38. 2. Re-radiation of long-wave radiation from earth’s surface
Short wave radiation is absorbed by earth
Reradiates long wave infrared radiation also called terrestrial radiation
Gases in the atmosphere absorb this infrared reradiation and are heated

40. 3. Conduction Transfer of heat by direct molecular contact
Not all heat energy in rocks reradiate back
Some is through direct contact of the hot rocks with the atmosphere

41. 4. Latent heat of condensation
Water vapor condenses to liquid water - Release (condensation) of latent heat
gain (evaporation) of latent heat – cooling effect

42. Ex) body sweat evaporates and draws heat away from your body
Ex) body sweat evaporates and draws heat away from your body. The heat is stored in water vapor and rises in the atmosphere.
When it condenses, heat is releases as latent heat.
Clouds form and massive storm systems
Body sweat may help form a cloud!!