1. Earth’s energy IMBALANCE
The effect of geography
Global air circulation

2. Despite its nearness, and great size, the radiant energy from the sun does not heat equally all places on Earth.
150,000,000 km
1 Astronomical Unit
1 AU

3. Heating of the Earth varies because Earth is a sphere

4. The spherical shape means the the angle of the suns rays varies
Radiant energy strikes Earth at the equator directly overhead, at 90 degrees, focusing the energy on a small area
Radiant energy strikes the poles at a smaller (acute) angle, spreading the energy out over a larger area

5. Sun appears lower in the sky
90° angle
1mi > 2 mi = 4x? Inverse square law!
Earth surface

6. Heating of the Earth varies because its tilted on it’s axis

7. The tilt is constant, so as Earth revolves about the Sun, the angle of the Sun’s rays changes
23.5 degrees
The Earth’s axis is tilted at an angle of 23.5° away from the plane of the ecliptic. And it’s because of this tilt that we have seasons here on Earth.
To better understand this, first we have to think of the Sun. Imagine there’s a line passing through the north pole and south poles of the Sun. This is the Sun’s axis of rotation. Then imagine a disk coming out from the Sun’s equator in all directions. This disk is called the plane of the ecliptic, and it’s where all of the planets in the System are located. Astronomers then measure the axis of rotation passing through each of the planets. The axial tilt of each planet is measured by the angle it makes compared to the Sun’s axis of rotation.
And so, in the case of our planet, the Earth’s axis measures 23.5° away from the Sun’s axis of rotation.
(This is why there are seasons)

8. Northern Hemisphere tilted AWAY FROM the sun
Therefore angle of radiation is lower
Northern Hemisphere tilted TOWARDS sun
Therefore radiation angle is greater
Fact: • Earth’s orbit is an ellipse
• farthest from the sun in Jan & June (1.6 million mi)
Don’t fall for the misconception that Earth is closer to the sun in summer!

9. Different materials have different specific heat capacities* (SHC)
* the energy needed to change a materials temperature by 1C
SHC reflects capacity for storing energy
SHC determines how easily a material changes temperature

10. Water has a high specific heat capacity takes a lot of energy to break H bonds between between adjacent water molecules
Water has a higher specific heat/slow to warm and cool
Land heats & cools quickly
Oceans are slow to change temperature
sand
water

11. absorbed energy has little effect on T
little seasonal T change
absorbed energy effects T more
more seasonal T change
coastal inland
(L.A.) (Phoenix)

12. Earth’s spherical shape, axial tilt, and different surfaces (land vs ocean) result in an energy imbalance, with effects across the planet

13. EFFECT: Global Circulation
At altitude the ‘bubble’ of warmed air cools and sinks.
Heated air is less dense, rises
Creates vertical air flow

14. Less dense warmed air has lower pressure; More dense sinking air creates zones of high pressure
EFFECT: surface winds as the sinking air flows in to
take the space of the rising air
EFFECT: Variations in air pressure
within a convection cell,
and planet-wide

15. in cells and planet-wide
Cooling air holds less water vapor; condensation into liquid water occurs
EFFECT: clouds
form
in cells and planet-wide
Add a video of equatorial clouds!

16. EFFECT: Global precipitation patterns
Add a video of equatorial clouds!
low high

17. air temp + precipitation = climate
EFFECT: global ecosystems
Add a video of equatorial clouds!

18. aka biomes

19. Effect? one big convection cell from equator to pole with surface winds flowing between poles.
Nope! actual:
Why not?

20. Earth rotates on its axis, creating the Coriolis Effect
The air above Earth’s surface (or a plane) although moving straight, appear to be on a curved path as the Earth rotates beneath them
Add video
The Earth rotates to the east at an effectively constant angular velocity, but different latitudes have different linear speeds. A point at the equator has to go farther in a day than a point in Ohio, so it must go faster.
objects moving north or south and not firmly connected to the ground (air, artillery fire, etc) maintains its initial eastward speed as it moves. An object leaving the equator will retain the eastward speed of other objects at the equator, but if it travels far enough it will no longer be going east at the same speed the ground beneath it is.
The result is that an object travelling away from the equator will be heading east faster than the ground and will seem to be forced east by some mysterious force. Objects travelling towards the equator will be going more slowly than the ground beneath them and will seem to be forced west. In reality there is no actual force involved, the ground is simply moving at a different speed than the object is "used to".
The equator has the greatest rotation – further distance to cover, so greater speed – and so most pronounced Coriolis effect
Most pronounced between equator and poles

21. EFFECT: A set of convection cells, every 30 degrees of latitude
Add video

22. EFFECT: Winds appear deflected again, planet-wide to the right in the
northern hemisphere
to the left in the
southern hemisphere

23. Global winds no wind 60 30 Doldrums Tradewinds Horse latitudes
Doldrums
Tradewinds
Horse latitudes
Westerlies
Polar easterlies
at Windy.com

24. EFFECT: Surface winds move the surface waters of the oceans, creating ocean currents
again, to the right in northern hemisphere, left in southern
again, planet-wide at Windy.com

25. Sidebar: gyres collect/concentrate garbage
Need to clean up!
via bacteria
via boom

26. Well, maybe not so simply….

27. EFFECT: Localized Circulation
Warmed air:
greater energy
less dense
lower pressure
Air rises
A summer day
Onshore winds
Cooling air :
losing energy
more dense
higher pressure
Air sinks
A summer night
Small scale video example
Offshore winds