The hydrologic cycle begins with the evaporation of water from the surface of the ocean. As moist air is lifted, it cools and water vapor condenses to form clouds. Moisture is transported around the globe until it returns to the surface as precipitation. Once the water reaches the ground, one of two processes may occur; 1) some of the water may evaporate back into the atmosphere or 2) the water may penetrate the surface and become groundwater.
Groundwater either seeps its way to into the oceans, rivers, and streams, or is released back into the atmosphere through transpiration. The balance of water that remains on the earth’s surface is runoff, which empties into lakes, rivers and streams and is carried back to the oceans, where the cycle begins again
likelihood of sheet flow runoff depends on the infiltration of the soil:;what are some of the characteristics of it(5)
soil textureslope of landintensity and duration of rainfallprior wetted condition of soilnature of vegation cover
what are drainage basins?;how is it seperated?
area the contributes water to a river system.;seperated by a divide ranging in scale from a ridge to a contiental divide
what are the 3 zones of a river system?;can all 3 happen in one zone?
erisionsediment transportdeposition;;yes, but one will always dominate;
what is laminar stream flow?
slower and straight
what is turbulent stream flow?
faster not straight
what determines the velocity of streamflow?
gradientshape, size and roughnessdischarge
what is graident?
change in elevation (vertical drop)/distance
the steeper the gradient..
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thick mass of ice the origonates on land from the accumlimation, compaction and recrystalization of snow.
types of glaciers;-exists in mountanious aresflow down a valley from an accumulation center at its head
valley (alpine) glacier
types of glaciers;-exist on a larger scale then valley glacierstwo major ones on earth are over greenland and antartica;
ice sheets;often called contential ice sheets
all types of glaciers (5);
valley (alpine)ice sheetsice capsoutlet glacierspiedmont glaciers
what would happen if the ice melted on earth
sea level would rise 60-70 meters
slightly more then what % of the worlds water is tied up in glaciers
what are the characteristics of the Antartic ice sheet
-80% of the worlds ice-nearly 2/3 of earths freshwatercovers almost 1 1/2 times the area of the United States
where do glacies form
areas where more snow falls in winter then it melts during the summer
how does a glacier form5 steps
-air infiltrates snow-snowflakes become smaller, thicker, and more spherical-air is forced out-snow is recrystallized into a much denser mass of small grains called firn.-once the thickness of ice and snow exceed 50 meters, firn fuses into a solid mass of interlocking crystals—-glacier ice
2 tyoes of glacier flow & describe them.
-plastic flow:occurs within the ice…under pressure, ice behaves as a plastic material -basal slip: entire mass slipping along the ground.
..most glaciersare thought to move this way
movement of glaciers is refered to as….
. zone of fracture is occurs where and is what
– as flow -occurs in the uppermost 50 meterstension causes crevases to form in brittle ice
glaciers form at what zone
zone of accumlation
glacires erode the land in two ways, descibe how
-plucking: lifting of rocks-abrasian: rocks within the ice act like sandpaper to smooth and polish the surface below.
erosioanl features created by glacial erosion in valleys(9)
till is material that is depositied directly over ice stratified drift sediments laid down by glacial meltwater
indirect effects of Ice Age Glaciers(6)
-forces migration of plants and animals-changes in stream courses-rebounding upward of the crust in former centers of ice accumlation-worldwide change in sea level-climatic changes-pluvial lakes
causes of glaciation the Milankovitch Hypothesis(4)
-shape(ecentricity) of earths orbit varies-angle of earths axis(obliquity) changes-earths axis wobbles (precession)-changes in climate over the past several hundred years are closely associated with variations in the geometry of earths orbit
dry climates are composed of —% of earths land surface
what and where are low latitude deserts
–subtropical heights-as air sinks it compresses and warms-very low relative humidity –tropics of cancer and capricorn
what and where are mid-latitude desertsexample?
–not associate with subtropical high pressure systems -occur in the middle of a large landmass on the leeward side of mountain ranges ex.
gobi desertrainshadow deserts
what is the rainshadow effect
-wind is forced to rise s it reaches a mountain range–air cools then condenses–moisture is precipatated out on the windward side before cresting the mountain– as air sinks on leeward side, it compresses and warms but is dry.
these are characteristics of what-short livedinfiltrate/evoprate before water can reach the ocean-only carry water in response to rainfalllasts only a few hours to a few days
–ephemeral streams (deserts)
desert rainfall1.rain occurs as ___ ____2. most erosion is done by ____ ____3.
vegatation is sparse so _____ is unhindered and ___ ___ are common
1.heavy showers2. running water3.
runoff, flash floods
how is transportation of sediment by wind different then running water?(2)
— wind is less capable of picking up and transporting course materials– wind is not confined to channels and can spread sediment over large areas
what are some characteristics of Dune (a form of wind deposit)
-mound or ridges of sand-often asymetrically shaped-windward shape is gently inclined and the leeward slope is called slipface
what are characteristics of Loess ( type of wind deposit)
blankets of windblown silt-primary sources are deserts and glacial outward deposits- extensive deposits occur in china and the central United States.
flat platform composed of sand and marked by change in a slope at seaward edge is the wet sloping surface the extends from the berm to the shoreline an accumlation of sediment found along the landward margin of an ocean or lake.
berm beach face a beach
wind generated waves provide most of the
energy that shapes and modifies shorelines
where do waves derive their energy and motion from
parts of a wavecresttrough measurements of wavewave heightwave lengthwave period
crest- top of the wavetrough- is the low area between waves wave height- distance between a trough and crestwave length- horizontial distance between crests ( crest to crest)wave period- time interval between the passage of the 2 sucessive crests.
height length and period of a wave all depend on
wind speedlength time wind has blownfetch (distance that the wind has traveled across open water)
wind erosion is caused by
wave impact and pressureabrasion by rock fragments
what is light wave activity
swash is likely to soak into the beach, decresing the amount of backwash net movement of sand up beach face toward berm
what is heavy wave activity
beach likely to be saturatedberm erodes because backwash is so strongnet movement iof sand is down the beach face
waves approach the shore at an ___ what happens to a wave as it reaches shallow water with a smooth sloping bottom
angle they are bent and tend to become parallel to the shore
consequences of wave refraction
wave energy is concentrated against the sides and ends of headlandswave attack is spread out and weakenedover time wave erosion straightens an irregular shoreline
waves along the beach moving in a zig-zag pattern is known as a ____
features of a shoreline vary depending on several factors like:
-rocks along the shore-currents-wave intensity-whether the coast is stable, sinking, or rising
shoreline wave erosion: (2) features associated with headlands: (2)
elongated ridges of sand extending from the land into the mouth of an adjacent bay
_____ is a sand bar that completly crosses a bay ______ is a ridge of sand that connects an island to the mainland or another island.
baymouth bay tombolo
barrier islands are mainly located ? what are barrier islands?
-along altantic and gulf coasts -low ridges of sand that run parallel to the coast 3 to 30 kilometers offshore
4 basic responses to shorline erosion
jetties: extend into ocean at the entrance to rivers and harbors groins: contsructed at a right angle to the beach to trap sand breakwaters: protect boats from the force of large breaking waves seawalls: stops waves from reaching the beach areas behind the wall
what is the most violent storm on earth
what is needed for a storm to be considered a hurricane?
wind speed more then 74 mphrotary cyclonic rotationprofileform between the latitudes of 5 and 20 degrees
emergent coasts develop because of…. 2 features
an uplift of an are or a DROP in sea level -wave-cut cliffs-wave-cut platforms
submergent coasts are caused by… 2 features
land adjacent to the sea or a RISE in sea level -highly IRREGULAR shores-estuarires-drowned river mouths
what makes up a spring tide
-occurs during new and full moons-produce esp high and low tides-large daily tidal range
what makes up neap tides
-occur during the first and third quarters of the moon-gravitional forces of the moon and sun are offset-daily tidal range is least