EARTHS ENERGY IMBALANCE The effect of geography Despite

EARTH’S ENERGY IMBALANCE The effect of geography

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

Ø Heating of the Earth varies because Earth is a sphere

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

90° angle Sun appears lower in the sky Earth surface

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

The tilt is constant, so as Earth revolves about the Sun, the angle of the Sun’s rays changes 23. 5 degrees (This is why there are seasons)

Northern Hemisphere tilted AWAY FROM the sun Therefore angle of radiation is lower Northern Hemisphere tilted TOWARDS sun Therefore radiation angle is greater Don’t fall for the misconception that Earth is closer to the

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

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

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

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

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

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

Cooling air holds less water vapor; condensation into liquid water occurs Ø EFFECT: clouds form in cells and planetwide

Ø EFFECT: Global precipitation patterns low high

air temp + precipitation = climate Ø EFFECT: global ecosystems

aka biomes

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

Ø 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 Most pronounced between equator and poles

Ø EFFECT: A set of convection cells, every 30 degrees of latitude

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

Global winds 60 no wind 30 0 Doldrums Tradewinds 30 Horse latitudes 60 Westerlies Polar easterlies at Windy. com

Ø 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

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

§ Well, maybe not so simply….

Ø EFFECT: Localized Circulation § Warmed air: greater energy less dense lower pressure A summer day Onshore winds Air rises § Cooling air : losing energy more dense higher pressure Air sinks A summer night Offshore winds