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.
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 30 o N & S latitude, Earth’s rotation moves air from West to East, as warm air moves to poles.
Many ongoing processes constantly change Earth.
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