1. differential heating effects
Standard 5a, b, c, d

2. Remember, All energy comes from the Sun!

3. Differential Heating
Some parts of earth get a lot of heat some parts of earth get less heat.

4. The sun’s rays hit the equator directly so it is hot at the equator
The sun’s rays hit the equator directly so it is hot at the equator. The sun’s rays hit the North and South poles at an angle so it is cold there.
bill nye clip

7. So, differential heating means that solar radiation is more concentrated at the _________, and less concentrated at the ___________ .

8. The Earth is tilted 23° South Pole Yorba Linda Mazatlan, Mexico
Homer, AK
Eureka
Yorba Linda
Mazatlan, Mexico
South Pole

9. Because the Earth is tilted, we have seasons.

10. Earth’s tilt

11. Tilt Experiment

12. Because the Earth is tilted, different parts of the Earth get more or less heat. This difference causes wind.
wind

13. Air currents

14. Differential heating of the Earth also causes ocean currents.

15. Water currents

16. Coriolis Effect 11. Differential Heating Trade Winds Polar Easterlies
Vocabulary for chapters 16, 19, 20 and 21 Due on April 26 (pictures and definitions)
Climate Current
Weather Elevation
Coriolis Effect Differential Heating
Trade Winds
Polar Easterlies
Barometer
Equator
Upwelling

17. Reasons for the Unequal Heating of Earth
lux meter app
lux meter for apple
Reasons for the Unequal Heating of Earth
Variation in the amount of surface area receiving solar energy
Near the poles the light is concentrated over a small surface area.
Light at the mid-latitude and polar regions is distributed over a large surface area, giving each square meter of surface less energy.

18. Climate is the state factor that most strongly governs the global pattern of ecosystem structure and processes
Climate is the state factor which is most important in explaining global patterns of ecosystem distribution and function. That’s why we have tundra near the poles or mountain tops and rainforest near the equator.

19. Climate is a key mechanism by which ecosystems interact with
the total Earth System

20. Major goals in this lecture
Understand how the climate system works

21. Half of solar radiation
Energy in = energy out
Half of solar radiation
reaches Earth
The atmosphere is transparent to shortwave but absorbs longwave radiation
(greenhouse effect)
The atmosphere is heated from the bottom by longwave radiation and convection
Let’s start by trying to understand the average energy budget of Earth.
Over a year, on average the amount of incoming energy must be balanced by the same amount of energy leaving Earth.

22. The temperature of a body determines wavelengths of energy emitted
Solar radiation has high energy
(shortwave) that readily penetrates
the atmosphere
Earth emits low-energy (longwave)
radiation that is absorbed by the
atmosphere

23. The atmosphere is heated from the bottom
Therefore it is warmest near the bottom,
and gets colder with increasing
elevation

24. Uneven heating of Earth’s surface causes predictable latitudinal variation in climate. Why? - Angle of incidence… equator vs. poles

25. For this reason, it’s warmer near the equator than at the poles.
Climatic Variation & Seasons on Earth
Uneven heating of Earth’s surface causes predictable latitudinal variation
in climate. Why? - Angle of incidence… equator vs. poles
North Pole
Equator
Earth
South Pole
Thus, radiation is more intense near the equator compared to the poles.
For this reason, it’s warmer near the equator than at the poles.

26. Latitude and season

27. North and south hemisphere

28. Seasons at the poles

29. 90 90

30. Thus, radiation is more intense near the equator compared to the poles
Thus, radiation is more intense near the equator compared to the poles. For this reason, it’s warmer near the equator than at the poles.

31. Uneven heating of Earth’s surface causes atmospheric circulation
Greater heating at equator than poles
1. sun’s rays hit more directly
2. less atmosphere to penetrate
Therefore
1. Net gain of energy at equator
2. Net loss of energy at poles
Now let’s look at regional variations in Earth’s energy budget

32. II. What about seasons? Why do we have them?
Earth’s distance from the sun varies throughout the
year – doesn’t that cause the seasons?
Tilt!
Because of the tilt of Earth’s axis, the amount of radiation received by Northern and Southern Hemispheres varies seasonally
A. Northern Hemisphere has summer when it tilts toward the sun, winter when it tilts away
B. Southern Hemisphere has summer when it tilts toward the sun, winter when it tilts away

33. Earth North Pole Equator South Pole Earth’s Seasons
Tilt of the Earth’s axis towards or away from the sun creates the seasons
When the north pole tilts toward the sun, it gets more radiation – more warmth
during the summer
SUMMER (Northern Hemisphere)
North Pole
Equator
Earth
When the north pole tilts toward the sun, the south pole tilts away
So when it’s summer in the north,
it’s winter in the south
South Pole
WINTER (Southern Hemisphere)

34. Earth North Pole Equator South Pole Earth’s Seasons
Tilt of the Earth’s axis towards or away from the sun creates the seasons
WINTER (Northern Hemisphere)
When the north pole tilts away
from the sun, it gets less radiation –
So it’s colder during the winter
North Pole
Equator
Earth
South Pole
When the north pole tilts away from the sun, the south pole tilts toward it…
When it’s winter in the north,
it’s summer in the south
SUMMER (Southern Hemisphere)

35. Air cools as it rises, moisture condenses and falls as rain
Intense radiation at the equator warms the air
Air cools as it rises, moisture condenses and falls as rain
Warm air rises, (low pressure) collecting moisture
Lots of rain in the tropics!

36. Dry air descends at around 30º N
Rising air is now dry…
some of the rising air flows north
some of the rising air flows south
…and at around
30º S
Dry air descends at around 30º N
The descending air flows N and S
Deserts
Deserts

37. Circulation patterns repeat
These are called convection cells – the basic units of
Vertical atmospheric circulation
Circulation patterns repeat
Hadley cells 0°
Dry
Wet
Dry
30°
60º
Wet
Wet
Polar cells (90º)
Dry
Dry

38. (vertical circulation)
Air rises and falls
in Hadley, Ferrel, and
Polar cells
(vertical circulation)
Circulation cells
explain global
distribution of
rainfall
Earth’s rotation
determines
wind direction
(horizontal circulation,
Coriolis force)

39. Sinking air is usually dry
It is high pressure
Latitude = 30° and 90°

40. Rising air is usually wet
It is low pressure
Latitude = 0° and 60°

41. Barometers measure air pressure.
When pressure is HIGH, the weather is clear and sunny.
When pressure is LOW, the weather is cloudy and rainy.

42. Sun’s rays experiment

43. Land temperatures fluctuate more, especially in higher latitudes
High heat capacity of water and ocean currents buffer ocean temperatures
Land temperatures fluctuate more, especially in higher latitudes
These differences in surface energy balance influence air movements, and create prevailing winds

44. In January…
At 30º N & S, air descends more strongly over cold ocean than over land
At 60 º N & S, air descends more strongly over cold land than over ocean
These pressure gradients create geographic variation in prevailing winds

45. In summer at 60 º N & S, air descends over cold ocean (high pressure) and rises over warm land (low pressure)
Cool equator-ward flow of air on W coast of continents Warm poleward flow of air on E coasts of continents

46. Ocean currents are similar to wind patterns:
1. Driven by Coriolis forces
2. Driven by winds

47. Arizona’s July temperature
>32ºC
29-32 ºC
27-29 ºC
24-27 ºC
21-24 ºC
18-21 ºC
16-18 ºC
13-16 ºC
Climate of any region is predictable from topography, wind and ocean currents

48. Ocean currents move 40% of “excess heat” from equator to poles
Driven by circulation of deep ocean waters
Deepwater formation occurs near Greenland and in Antarctic
60% of heat transport is carried by atmosphere through storms that move along pressure gradients

49. Landform effects on climate
Monsoon occurs due to seasonal patterns in ocean- land temperature differential
In eastern Asia during N. Hemi winter, because of less radiation, and because air over land has lower heat capacity than water in ocean, land is colder than the ocean
cold, dense air moves from land to ocean
In summer, land heats up more quickly (again because of lower heat capacity of air above land compared to water)
air over land rises, pulling moist air from ocean over land, causing seasonal monsoon

50. Mountain effects Rain shadow Effects of aspect
Air drainage (inversion, arising due to topography, where cold air settles in valleys, for example)

51. Climate effects on vegetation

52. Vegetation effects on climate
Vegetation can affect components of surface energy balance
Rt – r(a) = lE + C + G
1. Rt is total solar radiation reaching Earth
2. r is reflected radiation, a function of albedo (a)
3. lE is latent heat transfer, driven by evapotranspiration
4. C is convective heat transfer (sometimes called sensible heat flux)
5. G is storage

53. Vegetation can alter albedo
Leaf color
Land-use change:
Grazing, exposes soil, increases albedo, reducing net radiation, decreasing latent heat flux
Over large enough scales, such changes can alter regional precipitation
Similar phenomenon for deforestation
Tree migration into tundra
Tundra is snow-covered in winter, very high albedo
With warming, trees could advance, decreasing winter albedo dramatically
Potentially, creates a positive feedback to warming

54. Vegetation effects on climate
rough
smooth
Rough canopies promote turbulence, increasing air exchange and evapotranspiration (lE)
Smooth canopies have large boundary layers, impeding transfer of water vapor, decreasing latent heat flux (lE), increasing sensible heat flux (C) and storage (G)

55. variation in Earth’s orbit
How can the
atmosphere warm?
1. More solar radiation
variation in Earth’s orbit
2. Less reflected shortwave less sulfate aerosols darker surface of Earth (land-cover change)
3. More absorbed longwave
more “greenhouse gases”
Let’s start by trying to understand the average energy budget of Earth.
Over a year, on average the amount of incoming energy must be balanced by the same amount of energy leaving Earth.

56. Earth’s climate is now warmer than at any time in the last 1000 years
1. increased solar input (small warming effect)
2. Increased sulfate aerosols reflects radiation (small cooling effect)
3. Increased greenhouse gas concentrations (large warming effect)
4. Land-cover change creates a darker surface (large warming effect)

57. For our part of the world…

58. Climate also varies on longer time scales

59. Shape of orbit Wobble of tilt Angle of tilt
Changes in solar orbit causes long-term variations in solar input to Earth
Shape of orbit
Wobble of tilt
Angle of tilt

60. Eccentricity: The Earth's orbit around the sun is an ellipse
Eccentricity: The Earth's orbit around the sun is an ellipse. The shape of the elliptical orbit, which is measured by its eccentricity, varies through time.
The eccentricity affects the difference in the amounts of radiation the Earth's surface receives at aphelion and at perihelion.
When the orbit is highly elliptical, one hemisphere will have hot summers and cold winters; the other hemisphere will have warm summers and cool winters.
When the orbit is nearly circular, both hemispheres will have similar seasonal contrasts in temperature.

61. Pole Stars are Transient
Rotation axis executes a slow precession with a period of 26,000 years (see following figure)
Pole Stars are Transient
Wobble in the tilt

62. Precession: Present and past orbital locations of the Earth during the N Hemisphere winter

63. Most major greenhouse gases are increasing
in atmospheric concentrations

64. Climate is warming most rapidly at high latitudes This warming is most pronounced in Siberia and western North America

65. The Pacific Ocean strongly influences the climate system because
It is the largest ocean basin
Normal ocean current and wind direction in central Pacific is easterly

66. Interannual climate variation
ENSO events
Teleconnections carry these
climate effects throughout
the globe
(e.g., El Niño creates warm
winters in AK and Calif)

67. Functioning of ecosystems varies predictably with climate

71. Climate gives rise to predictable types of ecosystems

72. Distribution of ecosystems is predictable from global
patterns of wind and ocean circulation

75. What is an atmosphere?

76. Sun & moisture in weather

77. Sun and weather