what is the water cycle? - earth and environmental · ... continuous movement of water from the...
TRANSCRIPT
What is the water cycle?
} Continuous movement of water from the atmosphere to the earth�s surface and back to the atmosphere again.
} Transpiration - plants giving off water vapor into the atmosphere.
} Evaporation – liquid water changing into water vapor
} Condensation: water vapor (gas) changes into liquid water.
} Precipitation: water falls from clouds to the
ground.
} The underground water that fills almost all the pores in rock and sediment.
} Makes up 90% of the earth�s unfrozen freshwater supply.
} Aquifer: a body of rock in which large amounts of water can flow and be stored.
} Porosity: percentage of open spaces in rock. ◦ Determined by : ◦ Sorting: well-sorted- equal sized = more
porous ◦ Poorly sorted-unequal sized = less porous
} Permeability: how easily water flows through open spaces. (can water pass through or not?)
} Zone of Saturation: the layer of ground where all the pores are filled with water. ◦ The upper surface of the
zone of saturation is called the water table.
Russia
w Beginning of a river w Usually found in the
mountains. w Runoff from
mountains flows to lowest point.
w Smaller rivers that feed into a big river.
w More often found in mountains than on flat land.
w Where the river flows into a larger body of water
w Ex. a lake, ocean, another river.
w Watershed – area that drains into a body of water (stream, river etc.)
w River Basin - A region of land that drains into a river system (contains many different watersheds).
w Separates one river basin from the next.
w The course of the water in a river or stream.
w The volume of water flowing past a certain point in a given unit of time.
w Usually measured in cubic meters per second (m3/s).
w Young river: v-shaped channel; steep sides w Mature river: u-shaped channel; more sloping
sides; some meanders (bends) w Old river: flatter u-shaped channel; sloping
sides; lots of meanders
} Sediment is deposited in a stream when there is a decrease in the speed of the water.
} Decreased slope (steeper--> faster) } Bed widening (more friction) } Obstruction (slows down when it goes
around rock, tree, bridge)
} Can create landforms or change the river valley in the following ways:
} Sloping fan-shaped deposit of sediments } Occurs where a stream descending a steep
slope flat land.
} Part of the valley floor covered with water during a flood.
} Sediment is deposited making flood plains fertile.
} Raised river banks caused by flooding.
} Curves in a river caused by an obstruction. } Erosion occurs on the outside of a bend. } Deposition occurs on the inside of a bend.
} Crescent shaped body of water resulting when a part of a meander is cut off and abandoned by the river.
} Buildup of sediments at the mouth of a river. } Occurs because the water slows down as it
empties into another body of water.
Oceans and Ocean Circulation
70%!
96% PURE
WATER
4% dissolved elements:
Cl, Na, Mg S, Ca, K
} A measure of dissolved solids in sea water
} Number of grams of dissolved salts in 1 kilogram of water
} Measured in parts per thousand (ppt) (0/00)
} Evaporation and freezing increases salinity
} Density is the mass of a substance per unit volume (D=m/v)
} Affected by two things: ◦ Salinity: dissolved solids make water more dense ◦ Temperature: Cold water is more dense
Factors affecting Seawater density } Salinity–increase in salinityàincreases density } Temperture –decrease in tempàincrease density *Tempereature has a greater influence *Occurs at low latitudes. Thermocline is absent at high latitudes.
} Nitrogen (N2), Carbon dioxide (CO2), and oxygen (O2) are the most abundant
} CO2 dissolves most easily } Cold water holds more dissolved gases than warm water
} Divided into 3 major oceans: the Atlantic, the Pacific, and the Indian Oceans
Has the longest distance North to South
Covers 30% of surface of the Earth
Mostly in the Southern Hemisphere
} The Arctic and the Southern Oceans
} The term �sea� refers to smaller areas of the ocean that are partially surrounded by land.
Ex: Mediterranean and Caribbean.
} Ocean water moves in giant streams called currents that flow like rivers at the surface or far below.
} There are 2 types of currents: ◦ Surface ◦ Density
} Surface currents move on or near the surface of the ocean
} Surface currents are
driven by wind } They only affect the
upper surface of the water.
1.Warm: } Flow away from the
equator on the west sides of ocean basins
} Because areas near the equator are warm
} Example: Gulf
Stream
2. Cold } Flow toward the
equator on the east sides of ocean basins
} Originate at the poles where the water is cold
} Example: California
current
Red are Warm Currents and Black are cold currents
Surface Currents
} Wind is the driving force behind the formation of surface currents.
} 2 sets of wind patterns involved in forming
most surface currents. ◦ Trade Winds – Blow toward the equator ◦ Westerlies – Blow away from the equator
Trade winds and Westerlies
Five Major Ocean Gyres
1. North Pacific Gyre
2. South Pacific Gyre
3. North Atlantic Gyre
4. South Atlantic Gyre
5. Indian Ocean Gyre
} Western side of ocean has warm currents traveling from equator
} Eastern side of ocean has cool currents moving toward equator
} Move beneath the surface of the ocean
} Caused by differences in the density of water due to its different temperatures and salinities
} a.k.a.Thermohaline Circulation
Zone of rapid temperature change Warmer water on top of layer
Colder, denser on bottom of layer
} Begins at the poles where cold dense water sinks.
} Warmer water moves in to take its place creating a current.
} This drives the �global conveyer belt�
} Process moves very slowly } One section on the �global conveyer belt�
make take 1,000 years to fully cycle through the ocean!!
} Crucial to the base of the world's food chain. } Adds CO2 and nutrients to surface waters by
carrying them deeper in the ocean where those elements are abundant. ◦ This enables the growth of algae and seaweed
that ultimately support all forms of life. } Helps to regulate temperatures