Transcript Cycles of the Earth

Cycles of the Earth
Ch 18 Trefil & Hazen
The Sciences
All Matter above and beneath the
Earth’s surface moves in cycles.
What drives the earth cycles?
Sun radiates heat down
on the ocean of air
and water
Earth’s hot core or
geothermal energy
spreads upward
Demo and describe the water cycle
Water cycle constantly transfers the world’s
water between three basic storage reservoirs.
• Oceans contain 97% of Earth’s water
• Of the 3% of the Earth’s freshwater:
– 2.15% is locked away in glaciers and ice
sheets
– 0.62% is groundwater, stored as soil moisture
– 0.009% is in rivers and lakes
– 0.001% is in the atmosphere
Amazingly, the whole shebang of water in
lakes & rivers, water in rain & snow, water
in our bathtub, shower, and drink bottles,
amounts to only about 1% of the water in
the world.
The Water (Hydrologic) Cycle
• p. 442
• Ocean to Atmosphere
– 84% vapor from oceans; 16% from continents
• Atmosphere to Surface
– Vapor cools, condenses & precipitates out in a week,
or few hours or few centuries; depends.
– 77% precipitation falls on the oceans
• Surface to Ocean
– 23% of precipitation in water cycle meets our needs
via “surface water” and “ground water.”
Major steps in the water cycle:
• Ocean to
Atmosphere
• Atmosphere to
Surface
• Surface to Ocean
How do the different types of
precipitation form?
• Rain--Vapor condenses around aerosols
and falls from sky.
How do the different types of
precipitation form?
• Snow—ice crystals that assemble
themselves as they fall through a cloud
How do the different types of
precipitation form?
• Hail--large frozen rain formed in a giant
cloud of an intense thunderstorm.
How do the different types of
precipitation form?
• Sleet--falling snow may partially melt and
then refreeze into a frozen raindrop.
Motion of the Ocean
Discuss the cause/effect dynamics of
global ocean currents. link
Here’s a new perspective:
Explaining ocean motion: p. 441
• Great currents move the ocean, distributing
heat and regulating climate across Earth.
• General scheme
– Warm equatorial water swirls pole-ward and
circulates in vast ocean areas.
– Cool water moves around the poles and flows
toward equator as continents allow passage.
Atmospheric Convection on the
Rotating Earth p. 452
Trade Winds:
easterlies at equator
In the tropics, winds
prevail from E to W.
Air warmed new equator
travels pole-ward but
gradually cools and
sinks. Earth’s rotation
deflects surface winds
Atmospheric Convection on the
Rotating Earth p. 452
Polar Easterlies:
In the polar regions,
cold dense air sinks
and moves away from
poles.
Earth’s rotation deflects
surface wind from
East to West.
Atmospheric Convection on the
Rotating Earth p. 452
Westerlies
Near 30o N & S
latitude, Earth’s
rotation moves
air from West to
East, as warm air
moves to poles.
Many ongoing processes constantly
change Earth.
How do “rocks” “cycle” ?
Rock Cycle
Rocks
• Igneous = formed by the cooling and
crystallization of magma (melted rock)
• Sedimentary = formed from accumulation
of weathered material (sediments)
• Metamorphic = formed from preexisting
rocks that have been transformed (changed)
Igneous, Sedimentary, Metamorphic
 Each type of rock records a different
complex past.
 Each type of rock can be changed from
one form to another and back again.
 geologists call these transformations the
“rock cycle”
• Ch 18 pp. 464-465.
Try Discussion Questions 1-7,
And visit links on pacing guide:
Hydrologic cycle
Atmospheric cycle
Rock cycle