AP Environmental Science Why is water important? Water Compartments Water Distribution/ Water Cycle

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Water: The most important molecule?  Medium in which all life processes occur  Universal Solvent- Water dissolves nutrients and delivers it to your cells –Regulates body temperature –Removes wastes –Supports structures –60% of your body is water

Major Water Compartments Notes for pages

Water Distribution  Oceans 97.6%  Fresh water 2.4%  Freshwater Distribution (out of 100% of available freshwater)  Glaciers, ice and snow or “solid” water (68%)  Ground water (30%)  Lakes streams and rivers(2%)  Soil Moisture (.001%)  Atmosphere % of total water supply

Water Cycle There is some new stuff!

Water Cycle Terms  Evaporation-The process in which a liquid is changed into a gas (SURFACE WATERS)  Transpiration- the process of water moving from plants to atmosphere via photosynthesis  Sublimation-The process of going from a solid to a gas without ever becoming a liquid (GLACIERS)

Sublimation This is a picture of dry ice (frozen CO2) sublimating.

 Condensation- Water changes from gas to a liquid (cooling)  Dew Point -For a given amount of water vapor, the temperature at which condensation occurs  Condensation Nuclei- Tiny particles float in the air and facilitate condensation

Terms  Residence Time- amount of time an individual water molecule spends circulating in a body of water before it enters another phase of the hydrological cycle  The residence time of a water molecule in the ocean is about 3000 years

Groundwater  ms/groundwater/index.html

Terms  Infiltration- gravity pulls water downward through spaces in soil and rock  Zone of Aeration- upper layer of soil that holds both air and water  Zone of Saturation- lower layers of soil that has water filling every available space

Terms  Aquifers- porous layer of sand, gravel, or rock lying below the water table  Artesian well or spring- type of aquifer in which the water is highly pressurized. If it is piped or exposed at the surface it will gush without being pumped  Recharge zone- area of infiltration that continuously supplies the aquifer

Water Distribution  More than 70% of the earth’s surface is water  There are more than 1404 million cubic km or 370 billion gallons on earth  Theories on how water first got to our planet are a bit controversial

Rainfall and Topography  Mountains act as both cloud formers and rain catchers  Windward side of mountains- as the air sweeps up the mountain it is heavy with water, then it cools and rains out  Leeward Side of mountains- all of the moisture was left on the other side of the mountain, so it is dry. As it falls to a lower altitude it warms  Rain Shadow-dry area on the downwind side of the mountain

Rain Shadow

Desert Belts  Created by rising and falling air masses that result from global circulation patterns  Hot air rises at the equator, producing a lot of precipitation in the region (tropical rain forests)  As the air mass travels toward the poles the air is cooler and dryer, creating desert belts.

Distribution of Deserts